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WO2023233132A1 - Résines thermodurcissables recyclables - Google Patents

Résines thermodurcissables recyclables Download PDF

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Publication number
WO2023233132A1
WO2023233132A1 PCT/GB2023/051398 GB2023051398W WO2023233132A1 WO 2023233132 A1 WO2023233132 A1 WO 2023233132A1 GB 2023051398 W GB2023051398 W GB 2023051398W WO 2023233132 A1 WO2023233132 A1 WO 2023233132A1
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Prior art keywords
polymer
group
monomer
functionality
vinyl
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English (en)
Inventor
Steve RANNARD
Pierre Chambon
Stephen Wright
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University of Liverpool
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University of Liverpool
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F222/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides, or nitriles thereof
    • C08F222/10—Esters
    • C08F222/1006—Esters of polyhydric alcohols or polyhydric phenols
    • C08F222/102—Esters of polyhydric alcohols or polyhydric phenols of dialcohols, e.g. ethylene glycol di(meth)acrylate or 1,4-butanediol dimethacrylate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2/00—Processes of polymerisation
    • C08F2/38—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
    • C08J3/247—Heating methods
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins

Definitions

  • thermoset resins which can be recycled, i.e. can be recured by heating to reform into a thermoset resin, optionally one which has the same or similar properties to the original thermoset resin.
  • recyclable thermoset materials may be considered to be a class of vitrimers.
  • the recycling process may be facilitated by physically breaking down the resin (e.g. grinding it into powder) before reheating it to reform it into the further resin.
  • thermoset polymers or thermosets are used in many fields, particularly in construction and engineering sectors, and often exhibit high strength. After use, they are typically not recycled because they are difficult to repurpose or process into other useful materials, and often end up in landfill. This is environmentally disadvantageous and also economically undesirable.
  • the materials contain curable functional groups, which react under chosen curing conditions. The reactions which occur during curing typically entail the cross-linking of polymer chains together, and/or or the reaction of smaller molecules, oligomers or polymers to form larger entities, which are hardened, toughened or solidified materials. Several strategies are known for forming covalent linkages which result in cross-linked structures.
  • Methods can include, for example, one or more of: using hardeners or curing agents, using activating chemistry to affect reactivity, using initiators, and/or applying heat or irradiation.
  • the physical form of the cured thermoset product is typically not a thin coating, but rather is a 3D product, or part, which (in the case of recyclable thermosets) may be used again to form a further product.
  • the recyclable thermoset product may be used as an adhesive (bonding two substrate surfaces), may be used in a composite where two or more materials with different properties are combined and a curing reaction allows the formation of large 3D structures (e.g.
  • “large” could denote 5mm thick or larger), or may be used as a resin to cure to form a large 3D object (e.g., "large” could denote e.g. being 5mm or greater).
  • the cured material if recyclable may be used to form a second object, which may be a large object.
  • the recycling can entail recovering, grinding and reheating, but in some contexts recovering and grinding are not necessary or suitable; e.g. an adhesive joining together two large panels may be reheated to recure and secure the panels together.
  • durability, flexibility, insolubility, thermal resistance and/or solvent resistance may be important. UV stability can be important, and therefore in some instances the use of certain UV-absorbing components is avoided or controlled.
  • Possible curable functional groups include epoxy functional groups, as well as other groups, including amine functional groups, carboxylic acid functional groups, hydroxyl groups and isocyanate groups. During curing, where the functional group is an epoxide, said epoxide is ring-opened and a covalent bond is formed to another moiety, thereby resulting in a cured, cross-linked structure.
  • Polymers which contain curable epoxide groups are commonly referred to as epoxy resins.
  • epoxy resins often have a low molecular weight, in order to achieve sufficient epoxy groups to effect a good level of curing and hence effective thermosets with good physical properties.
  • the “epoxy equivalent weight” of an epoxy resin is the weight of epoxy resin per epoxy group. The higher the epoxy equivalent weight, the fewer epoxy groups are present per unit weight of resin. In certain contexts, it is desirable to have a low epoxy equivalent weight, and this is easier to achieve with smaller molecules. In the context of polymers, as the molecular weight of the material increases, it is typically more difficult to maintain the same ratio of epoxy groups to weight of the material.
  • a polymer manufacture method may result in a set number of epoxy groups per polymer molecule, so for example a polymer chain with two terminal epoxy groups with a nominal molecular weight of 1000 may be compared to the same system where the nominal molecular weight is 2000: both may be chain extended polymers made by the same process, but the epoxy equivalent weight for the former is 500 whereas the epoxy equivalent weight for the latter is 1000.
  • a higher molecular weight polymer may conventionally have a lower concentration of epoxy groups, which impacts on the curing reaction.
  • syntheses are typically more complex, and the materials may be mixtures containing a range of components with a distribution of molecular weights.
  • step growth polymers making “ultra high molecular weight” polymers is normally done by reacting monomers A2 + B2 to yield an intermediate AABBAA, and then using a second step to distil out the AA monomer to yield a long chain -AABB-. This negates the need to carefully balance the stoichiometry. These polymers are typically used for thermoplastic applications such as fibres and films. Performance is achieved via entanglement of the long chains.
  • molecular weight is achieved by the stoichiometric balance of AA and BB monomers. In principle this is straightforward (if extremely sensitive), but in practice it is extremely difficult: the sensitivity to monomer ratio means any weighing errors result in off-spec product.
  • Monomer purity compounds the problem, as monomers normally have some (small) fraction of mono and non-functional component. These lead to dead chain ends that cannot further react.
  • the statistical nature of the reaction means that the final reaction mixture will contain a range of molecular weights from monomers, dimers, trimers up through higher species. Some of these can be cyclic species where a polymer A--------B has looped back on itself to react and close a loop.
  • High molecular weight curable resins may provide considerable additional properties that are derived from the extended backbone of the resin and are difficult to build into a 3D structure during network formation through curing. However, conventionally, high molecular weight resins can be very viscous and have a very low concentration of curable functional groups.
  • the present invention relates to adhesives, composites and cured objects. Particular properties are relevant and desirable with such 3D objects. When moulding a 3D object and curing, one aim is for the structure to be the same size as the mould.
  • Shrinkage is a known problem, and high molecular weight resins offer the opportunity to mediate or even prevent such shrinkage. Formation of polymers from low molecular weight materials can lead to a decrease in volume and therefore shrinkage. Higher molecular weight resins typically require fewer reactions to reach a gelled crosslinked network and have the potential to diminish the extent of shrinkage during cure. Lower molecular weight materials can also be associated with higher levels of toxicity.
  • Types of backbone which may be used in curing systems include polyester backbones and polyurethane backbones. Curable materials with these types of backbone are effective, but conventionally they have been made by step-growth polymerisation methods.
  • Step- growth chemistry imposes restrictions on the types of polyester architecture or polyurethane architecture which can be made, and on the positioning and frequency of curable groups present and how they are incorporated. It also is not compatible with certain other types of backbone. It would be desirable to have different methodology which is more flexible and addresses some of the problems of step-growth methods. For example, conventionally, after the primary structure of a polymer has been prepared by step-growth polymerisation, curable functional groups may be added, for example by reaction of -OH groups with epichorohydrin to add epoxide groups: this extra process step can be challenging in terms of yield and reaction rate, and epichlorohydrin is highly toxic. It is desirable to have a more effective method of providing curable groups within the polymer.
  • thermoset materials could be prepared using step-growth chemistry and the curing of low molecular weight materials, these are associated with several disadvantages. It would be useful also to have a synthesis method that uses free radical chemistry, (which has the benefit of speed and reduces stoichiometry issues), which allows the preparation of high molecular weight resins, which facilitates control of curable group equivalent weight, and which facilitates recyclability. It would also be useful to have methodology which allows the preparation of thermoset materials which exhibit good properties and which are also recyclable. Surprisingly we have now found that a certain class of polymers is particularly well suited to these objectives.
  • the present invention provides a recyclable thermosetting composition
  • a recyclable thermosetting composition comprising a polymer which is a branched vinyl polymer prepared by transfer-dominated branching radical telomerisation (TBRT) of multivinyl monomer(s) and optionally monovinyl monomer(s) in the presence of chain transfer agent(s), and wherein said polymer comprises curable functional group(s), wherein said curable functional group(s) is/are selected from: an epoxy group; an acid group or other reactive carboxyl or acyl functionality; a hydroxy group or activated hydroxy group; an isocyanate group or blocked isocyanate group; or an amine group.
  • a thermosetting composition is a composition which can be cured to form a thermoset resin.
  • thermosetting composition is a recyclable thermosetting composition, i.e. said resin can be recycled, i.e. can be recured by heating to reform into a thermoset resin.
  • the resin is physically broken down (e.g. ground into powder) before said heating.
  • the reformed resin has the same or similar properties to the original thermoset resin.
  • the resin can be recycled a plurality of times. It is surprising that polymers of this type react under curing conditions to form thermoset materials, and furthermore that said thermoset materials are recyclable. Branched polymers are globular and would not necessarily be assumed to entangle and readily form crosslinked networks.
  • compositions may comprise, and indeed typically comprise, in addition to a curable resin, one or more additional component(s) selected from other reactive ingredient(s), pigment(s), filler(s), and/or additive(s).
  • the composition of the present invention may comprise, in addition to the polymer, one or more additional component(s) selected from other reactive ingredient(s), pigment(s), filler(s), and/or additive(s).
  • the composition of the present invention may comprise, in addition to the polymer, other reactive ingredient(s).
  • the present invention uses TBRT technology which allows control over the location of the curable functional groups (e.g. epoxy groups). It also provides more possibilities to alter equivalent weights of curable groups (e.g. epoxy equivalent weight). It is not reliant on step-growth syntheses, and can provide high molecular weight resins with controllable properties which are highly branched and so have low relative viscosities.
  • Branched vinyl polymers produced by TBRT which may be termed “branched vinyl TBRT polymers”, are a recognised group of polymers, as described in S. R. Cassin, P. Chambon and S. P. Rannard, Polym. Chem., 2020, 11, 7637-7649 and patent publications WO 2018/197885, WO 2018/197884 and WO 2020/089649.
  • branched vinyl TBRT polymers Following research into some properties and possible uses of said branched vinyl TBRT polymers, we have found that they are particularly well-suited for use in recyclable thermoset compositions when curable functional group(s) are present on the polymers.
  • the polymerisation of vinyl monomers using free-radical chain- growth chemistry is well known. Where a vinyl monomer has only one polymerisable vinyl group (i.e. is a monovinyl monomer), polymerisation of said monomer typically results in a linear polymer. Where a vinyl monomer has more than one polymerizable vinyl group (i.e. is a multivinyl monomer), e.g. has two polymerisable vinyl groups (i.e.
  • TBRT is a method for controlling branching during the free radical polymerisation of multivinyl monomers. It entails controlling the extent of propagation relative to the extent of chain transfer, and results in a hyperbranched polymer containing a large number of interconnected linear vinyl polymer chains, wherein the average length of each linear vinyl polymer chain is short.
  • TBRT is a type of telomerisation.
  • Telomerisation is a method of polymerisation of a polymerizable monomer (a “taxogen”) having an unsaturated group, resulting in a chain of taxogen residues (“taxomons”) with fragments of a further molecule (a “telogen”) attached terminally to the chain of taxomons.
  • taxogen polymerizable monomer
  • telogens chain of taxogen residues
  • a telogen fragments of a further molecule
  • the taxogen is a multivinyl monomer (often a divinyl monomer) and the telogen is a chain transfer agent (often a thiol RSH in which, according to the above terminology, Y is RS and Z is H).
  • a thiol RSH in which, according to the above terminology, Y is RS and Z is H.
  • thermosetting resins have typically been manufactured by step growth polymerisation methods, and it is conceptually very different to consider manufacturing them by chain growth methods, such as by free radical polymerisation.
  • chain growth methods such as by free radical polymerisation.
  • the creation of a thermoset resin requires the formation of a backbone polymer (polyester for example) whilst controlling monomer ratios so that the molecular weight is not high and so that the chain ends have the appropriate functionality – for example hydroxyl – to be derivatised.
  • Hydroxyl groups can then be reacted with epicholorohydrin (ring opening the epoxy to form a hydroxyl-alkyl chloride) and subsequent ring closing reforms an epoxy ring.
  • epicholorohydrin ring opening the epoxy to form a hydroxyl-alkyl chloride
  • ring closing reforms an epoxy ring.
  • epichlorohydrin is highly toxic.
  • the free-radical polymerisation of vinyl groups allows rapid synthesis, avoids the complexities of step-growth monomer addition and ratios, and allows large-scale synthesis without condensation products.
  • functional vinyl monomers leads to the formation of the product in one reaction step at levels of curable functional group that are dictated by monomer feed, and functional group equivalent molecular weights that are not dependent on the molecular weight of the final polymer.
  • the controlled free radical polymerisation methodology of the present invention is not only effective but also opens up new possibilities.
  • the polymer system of the present invention may be catalyst- free, though catalysts may be employed if required.
  • the polymer may be cured into a thermoset resin, optionally ground into powder, and then thermally recured into a thermoset without significant loss of properties. This can be demonstrated through two or more cycles and is highly unusual, reflecting the benefits of resins that are accessible through TBRT approaches.
  • the resins may be functional resins.
  • the resins may be of high molecular weight or very high molecular weight.
  • the resins may be of low viscosity. Without wishing to be bound by theory, the recyclability of the resins may be due to bond exchange, i.e.
  • recuring may result in the forming of an ester linkage where previously the resin had contained ester linkages but in different location(s), so in effect the recuring may include transesterification.
  • carbamate linkages may be reformed.
  • the presence of functional groups within the cured resin may lead to interchange (e.g. transesterification or transcarbamoylation) of network bonding and allow the reforming of functional groups.
  • an ester or a carbamate at a first location and a hydroxyl at a second location may convert to a hydroxyl at said first location and an ester or carbamate at said second location.
  • the TBRT methodology of the present invention allows several curing options, for example: a) TBRT polymers with just epoxy groups (thermal epoxy-epoxy reactions); b) TBRT polymers containing different functional groups (eg epoxy and acid); c) TBRT polymers containing one type of functional group plus small multi functional molecules (B2 and higher) - eg epoxy TBRT polymer plus small molecule diacid; d) TBRT polymers containing one type of functional group plus a linear polymer (functional at its chain ends or other) - eg epoxy TBRT plus polyacid; acid TBRT plus polyester epoxy; e) combinations of any of the above - eg adding a TBRT polymer into a conventional resin formulation.
  • the high molecular weight and branched architecture enabled by the present invention provides options that were not previously available, for example in terms of viscosity characteristics, Tg behaviour, and consequent properties and applications.
  • high molecular weight leads to issues of epoxy equivalent weights (EEW)
  • the present invention provides the possibility of high molecular weight (if desired) and controlled low EEW (if desired) at the same time, and this offers beneficial options for formulation and property control.
  • a further advantage of the present invention is the expansion of structural space in the thermosets area.
  • the present invention provides and uses new and diverse chemistries that are not normally available to thermosets. These would be difficult to prepare or difficult to scale at low cost. Examples include the preparation of alkylparaphenylenes from divinyl benzene (DVB).
  • Polymers produced by TBRT of multivinyl monomers exhibit interesting and unusual properties. They are formed by chain-growth polymerisation, yet may exhibit characteristics of step-growth polymers. Retrosynthetic analysis of some TBRT vinyl polymers can cause them to be viewed as comprising a mixture of polyfunctional step- growth monomer residues. Although they are vinyl polymers, many of them do not resemble vinyl polymers because their chemistry may be dominated by functional groups present in the parts of the multivinyl monomer which link the vinyl groups, and/or by functional groups in the chain transfer agent, and because the extent of reaction between vinyl groups is limited to low numbers such that the vinyl polymer segments within the polymer are short.
  • TBRT methodology enables new architectures containing step-growth motifs which would be difficult or impossible to achieve using step-growth polymerisation.
  • the methodology may also be understood when defined using different terminology to achieve the same or similar outcomes. Therefore, from second, third and fourth aspects, the present invention can be defined as follows.
  • the present invention provides a recyclable thermosetting composition
  • a polymer which is a branched polymer prepared by free radical vinyl polymerisation comprising residues of multivinyl monomer(s), residues of chain transfer agent(s), and optionally residues of monovinyl monomer(s), and wherein said polymer comprises curable functional group(s), wherein said curable functional group(s) is/are selected from: an epoxy group; an acid group or other reactive carboxyl or acyl functionality; a hydroxy group or activated hydroxy group; an isocyanate group or blocked isocyanate group; or an amine group.
  • the present invention provides a recyclable thermosetting composition
  • a polymer which is a branched polymer comprising vinyl polymer chains wherein the vinyl polymer chains comprise residues of vinyl groups of multivinyl monomers and optionally monovinyl monomers, wherein the longest chains in the polymer are not the vinyl polymer chains but rather extend through the linkages between double bonds of the multivinyl monomers, and wherein said polymer comprises curable functional group(s), wherein said curable functional group(s) is/are selected from: an epoxy group; an acid group or other reactive carboxyl or acyl functionality; a hydroxy group or activated hydroxy group; an isocyanate group or blocked isocyanate group; or an amine group.
  • the present invention provides a recyclable thermosetting composition
  • a polymer which is a step-growth polymer comprising a mixture of polyfunctional step-growth monomer residues formed by vinyl polymerisation, and wherein said polymer comprises curable functional group(s), wherein said curable functional group(s) is/are selected from: an epoxy group; an acid group or other reactive carboxyl or acyl functionality; a hydroxy group or activated hydroxy group; an isocyanate group or blocked isocyanate group; or an amine group.
  • the recyclable thermosetting composition may comprise, in addition to the polymer, one or more additional component(s) selected from other reactive ingredient(s), pigment(s), filler(s), and/or additive(s).
  • the recyclable thermosetting composition of the present invention may comprise, in addition to the polymer, other reactive ingredient(s).
  • thermosets may be used externally and environmental resistance in that context is desirable, including one or more properties selected from UV-, weather-, salt water -, temperature- and mechanical abrasion/stress - resistance
  • the present invention provides the use of the polymer defined in each of the first four aspects to form a recyclable thermoset.
  • the extent of propagation may be controlled relative to the extent of chain transfer to prevent gelation of the polymer.
  • the curable functional group(s) may be incorporated via the multivinyl monomer(s), via co- polymerised monovinyl monomer(s), or via chain transfer agent(s). Alternatively, or additionally, the curable functional group(s) may be incorporated by post-functionalisation, i.e.
  • the present invention allows the incorporation of more than one type of curable functional group in the same polymer. As shown in the figures, it is possible, for example, to have hydroxyl groups and epoxy groups in the same polymer, or acid groups and alcohol groups in the same polymer. Furthermore the present invention allows the incorporation of curable functional groups with backbone chemistry that would not conventionally be compatible.
  • the polymer may be defined by its curable functional group equivalent weight, i.e. the mass of polymer, in g, per mol of curable functional group.
  • the curable functional group is an epoxide
  • the curable functional group equivalent weight is the epoxy equivalent weight (EEW).
  • the curable functional group equivalent weight e.g.
  • the epoxy equivalent rate may optionally be within the range of 100 to 10,000 g/ mol, or 100 to 5,000 g/ mol, or 100 to 3,000 g/ mol, or 100 to 2,000 g/ mol, or 100 to 1,500 g/ mol, or 100 to 1,000 g/ mol, or 100 to 900 g/ mol, or 100 to 850 g/ mol, or 250 to 5,000 g/ mol, or 250 to 3,000 g/ mol, or 250 to 2,000 g/ mol, or 250 to 1,500 g/ mol, or 250 to 1,000 g/ mol, or 250 to 900 g/ mol, or 250 to 850 g/ mol, or 500 to 10,000 g/ mol, or 500 to 5,000 g/ mol, or 500 to 3,000 g/ mol, or 500 to 2,000 g/ mol, or 500 to 1,500 g/ mol, or 500 to 1,000 g/ mol, or 500 to 900 g/ mol, or 500 to 850
  • the curable functional group equivalent weight (e.g. the epoxy equivalent rate) may optionally be up to 1,500 g/ mol, or optionally up to 1,000 g/ mol, or optionally up to 900 g/ mol, or optionally up to 850 g/ mol.
  • the polymer i.e. the thermoset precursor, may be analysed by triple detection size exclusion chromatography (SEC).
  • the multivinyl monomer residue(s) may be divinyl monomer residue(s) and the polymer may comprise on average between 0.9 and 1.1 chain transfer agent residues per divinyl monomer residu
  • the multivinyl monomer may have more than two vinyl groups, i.e.
  • polymers which may be made from not only divinyl monomers but also, for example, trivinyl and/or tetravinyl monomers.
  • the polymer may comprise on average between 0.9 and 3.3 chain transfer agent residues per multivinyl monomer residue.
  • the polymer may comprise a multiplicity of vinyl polymer chain segments having an average length of between 1 and 3 multivinyl monomer residues.
  • the resins may be solid, liquid or dissolved in a diluent for application benefits.
  • the material may be suitable for injection moulding. Processability advantages and mitigation against shrinkage are brought about by the present invention.
  • One of the major advantages of the present invention is that extremely branched polymers can be achieved via radical polymerisation that would be impossible, or challenging, or extremely dangerous, to make using step growth polymerisation. It is advantageous to be able to control the polymerisation to avoid gelled polymers. Conventional step growth polymerisation methods have been known to result in gelled branched polymers within industrial-scale reactors, which have taken weeks to recover; this can clearly be very costly and time-consuming. Curable functional group(s) The polymers comprise curable functional groups.
  • curable functional groups are present in the polymers, in amounts which can be controlled and tailored by controlling the amount of feedstocks (monovinyl monomer, multivinyl monomer or chain transfer agent). For example, where an epoxide-carrying monovinyl monomer is used, the number of epoxide groups incorporated will correspond to the number of residues of said monomer in the polymer.
  • Suitable curable functional groups are sufficiently inert during storage and during preparation of the formulations, but reactive during curing conditions under reasonable timescales. They include the following groups: epoxy; carboxylic acid; carboxyl; amine; hydroxy; and isocyanate. They also comprise variants of the same, which variants also exhibit suitable cross-linking chemistries: these variants can control reactivity – e.g. activated functional groups (including activated alcohols) and blocked hardeners (e.g. blocked isocyanates).
  • the curable functional group may be an epoxide.
  • a monovinyl monomer may comprise, in addition to a polymerisable double bond, an epoxide group.
  • a suitable monovinyl monomer is glycidyl methacrylate.
  • the curable functional group may be an acid.
  • a monovinyl monomer may comprise, in addition to a polymerisable double bond, an acid group.
  • a suitable monovinyl monomer is methacrylic acid.
  • the curable functional group may be a hydroxyl group.
  • a monovinyl monomer may comprise, in addition to a polymerizable double bond, a hydroxyl group.
  • a suitable monovinyl monomer is hydroxyethylmethacrylate.
  • a divinyl monomer and/or a chain transfer agent may comprise one or more hydroxyl group.
  • the curable functional groups react. Curing can be effected by heat or by reaction with other reagents, or with each other, to form covalent linkages which can result in cross-linked network structures.
  • the recyclable thermosetting composition comprises a polymer comprising curable functional groups of one type which react with each other; for example, where the curable functional groups comprise epoxy groups, curing may occur by epoxy-epoxy reactions, e.g. thermal epoxy-epoxy reactions.
  • the recyclable thermosetting composition comprises a polymer comprising curable functional groups of more than one type which react with each other; for example, where the curable functional groups comprise epoxy groups and acid groups, curing may occur by reaction between those groups. It may be that separate reactive ingredients are added to react with the curable functional groups on the polymers thereby effecting curing. Said reactive ingredients may be as follows. Where the recyclable thermosetting composition comprises a polymer comprising curable functional groups which comprise an epoxy group, said recyclable thermosetting composition may further comprise one or more reactive ingredient which reacts with said epoxy group, wherein said reactive ingredient comprises for example functionality selected from hydroxy, amine, carboxyl, or epoxy.
  • the recyclable thermosetting composition comprises a polymer comprising curable functional groups which comprise an acid group or other reactive carboxyl or acyl functionality
  • said recyclable thermosetting composition may further comprise one or more reactive ingredient which reacts with said acid group or other reactive carboxyl or acyl functionality, wherein said reactive ingredient comprises for example functionality selected from hydroxy, or activated hydroxy.
  • said recyclable thermosetting composition comprises a polymer comprising curable functional groups which comprise a hydroxy group or activated hydroxy group
  • said recyclable thermosetting composition may further comprise one or more reactive ingredient which reacts with said hydroxy or activated hydroxy group, wherein said reactive ingredient comprises functionality selected for example from epoxy, acid or other reactive carboxyl or acyl functionality, isocyanate or blocked isocyanate.
  • the recyclable thermosetting composition comprises a polymer comprising curable functional groups which comprise an isocyanate group or blocked isocyanate group
  • said recyclable thermosetting composition may further comprise one or more reactive ingredient which reacts with said isocyanate group or blocked isocyanate group, wherein said reactive ingredient comprises for example hydroxy functionality.
  • said recyclable thermosetting composition comprises a polymer comprising curable functional groups which comprise an amine group
  • said recyclable thermosetting composition may further comprise one or more reactive ingredient which reacts with said amine group, wherein said reactive ingredient comprises for example epoxy functionality.
  • the above-mentioned reactive ingredients may be small molecules or may be polymers which carry said functionality.
  • the additional reactive ingredient may be a polymer which carries suitable reactive functionality (e.g. a polyacid), or by way of further example, where the curable functional group on the TBRT polymer is an acid, the additional reactive ingredient may be a polymer which carries suitable reactive functionality (e.g. a polyester epoxy).
  • a TBRT polymer may be added into a conventional resin formulation. In all cases, the combination of TBRT polymer(s) with themselves or with other TBRT polymer(s) or with other reactive components gives a resulting thermoset which is recyclable, i.e. which contains groups which can undergo bond transfer or bond exchange thereby allowing the reforming of functional groups.
  • stage 1 is the initial cure of the resin.
  • Stage 2 is the recure (during recycling). Recycling may occur several times and therefore stage 2 may occur several times.
  • Stage 2 may be facilitated: - either by functionality (e.g. OH) which has been generated during formation of the resin in the initial reaction (stage 1); - or by functionality (e.g. OH) which was present on one of more of the reagents (multivinyl monomer, monovinyl monomer or chain transfer agent) and which still remains unreacted after stage 1; - or both.
  • functionality e.g. OH
  • OH functionality which was present on one of more of the reagents (multivinyl monomer, monovinyl monomer or chain transfer agent) and which still remains unreacted after stage 1; - or both.
  • Types of branched polymers The branched vinyl polymers may be considered to be scaffolds to which the curable functional groups are attached, and may comprise any suitable chemistry. Suitable types of branched vinyl polymers include branched polyesters, which may be made from the polymerisation of monomers which comprise vinyl groups as well as ester- containing or ester-forming functionality.
  • Suitable monomers include methacrylates, acrylates and vinyl esters.
  • Suitable divinyl and multivinyl monomers include dimethacrylates, diacrylates, divinyl esters, multimethacrylates, multiacrylates, and multivinyl esters.
  • Said branched polyesters may be aliphatic polyesters, or may be aromatic polyesters if aromatic groups are also present in the monomer(s), or may be mixed aromatic/ aliphatic polyesters.
  • Said branched polyesters may also contain other functional groups, for example by inclusion of certain chemical moieties within the monomers used in the feedstock. Therefore, further suitable types of branched vinyl polymers include branched poly(urethane-ester)s.
  • Suitable monomers include urethane dimethacrylate.
  • Types of polymer which have been found to be particularly effective in accordance with the present invention include epoxy-functional branched polyesters and epoxy-functional branched poly(urethane-ester)s.
  • Suitable types of polymer include but are not limited to those containing functionality selected from the following: carbonates; carbonate esters; amides; amide esters; urethanes; urethane esters; urethane amides; urethane carbonates; ureas.
  • the branched polymer may be prepared by the free radical polymerisation of a multivinyl monomer, and optionally a monovinyl monomer, in the presence of a chain transfer agent, using a source of radicals.
  • a curable functional group is present on the polymer and may be incorporated by being present on the multivinyl monomer, the monovinyl monomer and/or the chain transfer agent; or by post-functionalisation.
  • the extent of propagation may be controlled relative to the extent of chain transfer to prevent gelation of the polymer.
  • multivinyl monomer denotes monomers which have more than one free radical polymerisable vinyl group.
  • One particular class of such monomers are those which have two such vinyl groups, i.e. divinyl monomers.
  • the branched polymer may be prepared by the free radical polymerisation of a divinyl monomer, and optionally a monovinyl monomer, in the presence of a chain transfer agent, using a source of radicals.
  • a curable functional group is present on the polymer and may be incorporated by being present on the divinyl monomer, the monovinyl monomer and/or the chain transfer agent; or by post-functionalisation.
  • the extent of propagation may be controlled relative to the extent of chain transfer to prevent gelation of the polymer.
  • cross-linking and insolubility are avoided not by using a combination of a predominant amount of monovinyl monomer and a lesser amount of divinyl monomer, but instead by controlling the way in which a divinyl monomer, or other multivinyl monomer, reacts. In many cases no monovinyl monomer is present or required.
  • the branched polymer may be prepared by the free radical polymerisation of a divinyl monomer, and optionally a monovinyl monomer, in the presence of a chain transfer agent, using a source of radicals, wherein propagation is controlled relative to chain transfer to achieve a polymer having a multiplicity of vinyl polymer chain segments wherein the average number of divinyl monomer residues per vinyl polymer chain is between 1 and 3.
  • a curable functional group is present on the polymer and may be incorporated by being present on the divinyl monomer, the monovinyl monomer and/or the chain transfer agent.
  • the branched polymer may be prepared by the free radical polymerisation of a multivinyl monomer, and optionally a monovinyl monomer, in the presence of a chain transfer agent, using a source of radicals, wherein propagation is controlled relative to chain transfer to achieve a polymer having a multiplicity of vinyl polymer chain segments wherein the average number of multivinyl monomer residues per vinyl polymer chain is between 1 and 3.
  • a curable functional group is present on the polymer and may be incorporated by being present on the multivinyl monomer, the monovinyl monomer and/or the chain transfer agent.
  • the branched polymer may be prepared by the free radical polymerisation of a trivinyl monomer, and optionally a monovinyl monomer, in the presence of a chain transfer agent, using a source of radicals, wherein propagation is controlled relative to chain transfer to achieve a polymer having a multiplicity of vinyl polymer chain segments wherein the average number of trivinyl monomer residues per vinyl polymer chain is between 1 and 2.
  • a curable functional group is present on the polymer and may be incorporated by being present on the trivinyl monomer, the monovinyl monomer and/or the chain transfer agent.
  • the branched polymer may be prepared by the free radical polymerisation of a tetravinyl monomer, and optionally a monovinyl monomer, in the presence of a chain transfer agent, using a source of radicals, wherein propagation is controlled relative to chain transfer to achieve a polymer having a multiplicity of vinyl polymer chain segments wherein the average number of tetravinyl monomer residues per vinyl polymer chain is between 1 and 1.7.
  • a curable functional group is present on the polymer and may be incorporated by being present on the tetravinyl monomer, the monovinyl monomer and/or the chain transfer agent.
  • Multivinyl monomer may be incorporated, regardless of whether or not a monovinyl monomer is incorporated.
  • a monovinyl monomer may be any combination of two or more of a divinyl monomer, a trivinyl monomer, a tetravinyl monomer, or other multivinyl monomer, are incorporated, and that optionally a monovinyl monomer may also be incorporated.
  • the polymer contains more than one of each type of monomer and/or more than one type of chain transfer agent.
  • the polymer contains divinyl residues and monovinyl residues and chain transfer agent residues
  • the divinyl residues may be all the same or different
  • the monovinyl residues may be all the same or different
  • the chain transfer agent residues may be all the same or different.
  • Figure 3 shows a product formed using two different divinyl monomers plus one monovinyl monomer. Copolymerisations using mixed multivinyl monomers, mixed monovinyl monomers, and/or mixed chain transfer agents therefore enhance the options for preparing copolymers with a wide range of structures.
  • one way of preparing polymers containing urethanes and esters could be polymerisation of one type of monomer (e.g.
  • urethane dimethacrylate Another way of preparing polymers containing urethanes and esters could be copolymerisation of one type of monomer (e.g. a diester multivinyl monomer) to incorporate ester functionality and another type of monomer (e.g. a urethane-containing multivinyl monomer which does not include, or react to form, ester linkages) to incorporate urethane functionality.
  • the polymer is prepared by free radical polymerisation and any suitable source of radicals can be used. For example, this could be an initiator such as AIBN.
  • a thermal or photochemical or other process can be used to provide free radicals.
  • a large amount of initiator is not required; only a small amount of a source of radicals is required in order to initiate the reaction.
  • the skilled person is able to control the chain transfer reaction relative to the propagation reaction by known techniques. This may be done by using a sufficiently large amount of a chain transfer agent (CTA).
  • CTA chain transfer agent
  • the chain transfer agent caps the vinyl polymer chains and thereby limits their length. It also controls the chain end chemistry.
  • Various chain transfer agents are suitable and of low cost, and impart versatility to the method and resultant product.
  • the primary chains may be kept very short so that gel formation is avoided, whilst at the same time a high level of branching is achieved.
  • the polymer may be prepared by industrial free radical polymerisation. This is completely scalable, very straightforward and extremely cost effective. In contrast, some prior art polymers are more complex and/or more costly and/or require the use of initiator systems or more complex purification procedures.
  • the only reagents to prepare the branched polymer are one or more multivinyl monomer (for example a divinyl monomer), a chain transfer agent, a source of radicals, and optionally a solvent.
  • the present invention relates to polymers which can be prepared by the homopolymerisation of multivinyl monomers. Monovinyl monomers are not required to prepare the polymer.
  • the curable functional group may be present on a monovinyl monomer, but may alternatively be present on multivinyl monomer or chain transfer agent. Nevertheless, monovinyl monomers may be incorporated, i.e. optionally a copolymerisation may be carried out to produce the polymer.
  • Monovinyl monomers are convenient means of introducing curable functional groups.
  • the polymer may incorporate not only a divinyl monomer but also an amount, optionally a lesser amount, of monovinyl monomer.
  • the molar amount of divinyl monomer relative to monovinyl monomer may be greater than 50%, greater than 75%, greater than 90% or greater than 95%, for example.
  • the ratio of divinyl monomer residues to monovinyl monomer residues may be greater than or equal to 1:1, or greater than or equal to 3:1, greater than or equal to 10:1 or greater than or equal to 20:1.
  • more monovinyl monomer may be used.
  • the polymer may incorporate not only one or more divinyl monomer but also monovinyl monomer, wherein for example 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more, of the vinyl monomers used are divinyl monomers.
  • the polymer may incorporate not only one or more divinyl monomer but also monovinyl monomer, wherein for example 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more, of the vinyl monomers residues in the product are divinyl monomer residues.
  • monovinyl monomers is applicable not just with divinyl monomers but also with other types of multivinyl monomers.
  • the polymer may incorporate not only one or more multivinyl monomer but also monovinyl monomer, wherein for example 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more, of the vinyl monomers used are multivinyl monomers.
  • the polymer may incorporate not only one or more multivinyl monomer but also monovinyl monomer, wherein for example 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more, of the vinyl monomers residues in the product are multivinyl monomer residues.
  • the polymer may comprise on average between 0.25 and 5 monovinyl monomer residues per multivinyl monomer (e.g. divinyl) residue, for example 0.25 to 4, or 0.25 to 3, or 0.25 to 2, or 0.25 to 1, or 0.25 to 0.5, or 0.5 to 5, or 0.5 to 4, or 0.5 to 3, or 0.5 to 2, or 0.1 to 1, or 1 to 5, or 1 to 4, or 1 to 3, or 1 to 2, or 2 to 5, or 2 to 4, or 2 to 3, or 3 to 5, or 3 to 4, or 4 to 5.
  • Divinyl Monomer One type of multivinyl monomer residue which may be present in the polymer is a divinyl monomer.
  • the divinyl monomer contains two double bonds each of which is suitable for free radical polymerisation.
  • It may contain one or more other group which for example may be selected from, but not limited to: aliphatic chains; esters; amides; esters; urethanes; silicones; amines; aromatic groups; oligomers or polymers; or a combination of one or more of these; and/or which may optionally be substituted.
  • group which for example may be selected from, but not limited to: aliphatic chains; esters; amides; esters; urethanes; silicones; amines; aromatic groups; oligomers or polymers; or a combination of one or more of these; and/or which may optionally be substituted.
  • PEG groups or PDMS groups between the double bonds, or a benzene ring (e.g. as in the monomer divinyl benzene) or other aromatic groups.
  • Each vinyl group in the divinyl monomer may for example be an acrylate, methacrylate, acrylamide, methacrylamide, vinyl ester, vinyl aliphatic, or
  • the vinyl polymer chains in the final product are generally quite short and the chemistry of the longest chains in the polymer may be governed by the other chemical species in the monomer.
  • ester linkages e.g. dimethacrylates, such as EGDMA
  • amide linkages e.g. bisacrylamides
  • the polymers may be polyesters, polyamides or other polymers.
  • the monomer residues may comprise other linkages or moieties, (e.g. urethane units), thereby resulting in other types of polymer (e.g. polyurethanes).
  • the monomer residues may contain more than one type of moiety, thereby resulting in hybrid polymers.
  • monomers which contain, in addition to two vinyl groups, ester linkages and urethane linkages e.g. dimethacrylates containing urethane linkages, such as urethane dimethacrylate (UDMA)
  • UDMA urethane dimethacrylate
  • the divinyl monomer may be stimuli-responsive, e.g. may be pH, thermally, or biologically responsive.
  • the response may be degradation.
  • the linkage between the two double bonds may for example be acid- or base-cleavable, for example may contain an acetal group.
  • This allows the preparation of a commercial product which is a stimuli-responsive branched polymer.
  • a further step of cleaving divinyl monomer may be carried to remove bridges in the polymer, to produce product in which the linkages between vinyl polymer chains have been removed or reduced.
  • the polymer may be prepared using a mixture of divinyl monomers. Thus two or more different divinyl monomers may be copolymerised.
  • Multivinyl monomers other than divinyl monomers may be used, for example, trivinyl monomers, tetravinyl monomers and/or monomers with more vinyl groups. Trivinyl monomers, in particular, are useful, as they can be sourced or prepared without significant difficulty, and allow further options for producing different types of branched polymers. The discussion, disclosures and teachings herein in relation to divinyl monomers also apply where appropriate, mutatis mutandis, to other multivinyl monomers.
  • Chain transfer agent Any suitable chain transfer agent may be used. These include thiols, including optionally substituted aliphatic thiols, such as dodecane thiol (DDT).
  • Another suitable chain transfer agent is alpha-methylstyrene dimer. Another is 2-isopropoxyethanol. Other compounds having functionality which is known to allow the transfer of radical chains may be used. These can be bespoke to bring about desired functionality to the polymers.
  • the chain-end chemistry can be tailored by the choice of CTA. Thus, hydrophobic/ hydrophilic behaviour and other properties can be influenced.
  • Alkyl thiols can have quite different properties to alcohol-containing groups, acid-containing groups, or amine- containing groups, for example.
  • a mixture of CTAs may be used. Thus, two or more different CTAs may be incorporated into the product.
  • Relative amounts of chain transfer agent and divinyl monomer The relative amounts of chain transfer agent and divinyl monomer can be modified easily and optimised by routine procedures to obtain non-gelled polymers without undue burden to the skilled person.
  • the analysis of the products can be carried out by routine procedures, for example the relative amounts of chain transfer agent and divinyl monomer can be determined by NMR analysis.
  • At least 1 equivalent, or between 1 and 10 equivalents, or between 1.2 and 10 equivalents, or between 1.3 and 10 equivalents, or between 1.3 and 5 equivalents, or between 1 and 5 equivalents, or between 1 and 3 equivalents, or between 1 and 2 equivalents, or between 1.2 and 3 equivalents, or between 1.2 and 2 equivalents, of chain transfer agent may be used relative to divinyl monomer.
  • the presence of a large amount of chain transfer agent means that on average the primary vinyl polymer chains react, and are capped by, chain transfer agent, whilst they are short. This procedure amounts to telomerisation, i.e. the formation of short chains with small numbers of repeat units.
  • n+1 chain transfer agent moieties per n divinyl monomer moieties may be present per divinyl monomer moiety, optionally between 0.7 and 1.5, optionally between 0.75 and 1.3, or between 0.8 and 1.2, or between 0.9 and 1.1, or between 1 and 1.05, or approximately 1.
  • Relative amounts of chain transfer agent and trivinyl monomer Where the multivinyl monomer used is a trivinyl monomer, the following may optionally apply.
  • the reagents used optionally at least 2 equivalents, or between 2 and 20 equivalents, or between 2.4 and 20 equivalents, or between 2.6 and 20 equivalents, or between 2.6 and 10 equivalents, or between 2 and 10 equivalents, or between 2 and 6 equivalents, or between 2 and 4 equivalents, or between 2.4 and 6 equivalents, or between 2.4 and 4 equivalents, of chain transfer agent may be used relative to trivinyl monomer.
  • Relative amounts of chain transfer agent and tetravinyl monomer Where the multivinyl monomer used is a tetravinyl monomer, the following may optionally apply.
  • the reagents used optionally at least 3 equivalents, or between 3 and 30 equivalents, or between 3.6 and 30 equivalents, or between 3.9 and 30 equivalents, or between 3.9 and 15 equivalents, or between 3 and 15 equivalents, or between 3 and 9 equivalents, or between 3 and 6 equivalents, or between 3.6 and 9 equivalents, or between 3.6 and 6 equivalents, of chain transfer agent may be used relative to tetravinyl monomer.
  • chain transfer agent optionally at least 1 equivalent, or between 1 and 30 equivalents, or between 1.2 and 30 equivalents, or between 1.3 and 30 equivalents, or between 1.3 and 15 equivalents, or between 1 and 15 equivalents, or between 1 and 9 equivalents, or between 1 and 6 equivalents, or between 1.2 and 9 equivalents, or between 1.2 and 6 equivalents, of chain transfer agent may be used relative to multivinyl monomer.
  • chain transfer agent moieties are present per multivinyl monomer moiety, optionally between 0.7 and 4.5, optionally between 0.75 and 3.9, or between 0.8 and 3.6, or between 0.9 and 3.3, or between 1 and 3.15, or between approximately 1 and approximately 3.
  • the polymer may comprise on average between 0.9(x-1) and 1.1(x-1) chain transfer agent residues per multivinyl monomer residue, where “x” is the number of polymerizable vinyl groups on the multivinyl monomer.
  • x is the number of polymerizable vinyl groups on the multivinyl monomer.
  • the multivinyl monomer is a divinyl monomer
  • a typical polymeric molecule prepared as described herein will contain many vinyl polymer chains (each of which is on average quite short) linked together by the moiety which in the multivinyl monomer is between the double bonds. This is achieved by adjusting the conditions, including the amount of chain transfer agent, so that the rate of chain transfer competes with the rate of vinyl polymerisation to the desired extent.
  • the resulting chain length in this context is the kinetic chain length.
  • Extent of vinyl polymerisation when using divinyl monomers The number of propagation steps (i.e. how many divinyl monomers are added) before each chain transfer (i.e. termination of the growing vinyl polymer chain) needs to be high enough to generate a branched polymer but low enough to prevent gelation. It appears that an average vinyl polymer chain length of between 1 and 3, between 1 and 2.5, between 1 and 2.2, between 1 and 2, between 1.3 and 2, between 1.5 and 2, between 1.7 and 2, between 1.8 and 2, between 1.9 and 2, or between 1.95 and 2, or of approximately 2, divinyl monomer residues, is suitable.
  • a small number of vinyl polymer chains may contain significantly more divinyl monomer residues, for example as many as 10, 15, 18, 20 or more.
  • 90 % of the vinyl polymer chains contain fewer than 10 DVM residues, or 90% have a length of 7 or fewer, or 90% have a length of 5 or fewer, or 95% have a length of 15 or fewer, or 95% have a length of 10 or fewer, or 95% have a length of 7 or fewer, or 75% have a length of 10 or fewer, or 75% have a length of 7 or fewer, or 75% have a length of 5 or fewer, or 75% have a length of 4 or fewer, or 75% have a length of 3 or fewer.
  • the average vinyl polymer chain length, or kinetic chain length, in a scenario which assumes that there is no intramolecular reaction can be calculated as follows. If, as discussed above there are n+1 chain transfer agent moieties per n divinyl monomer moieties, and one chain transfer agent per vinyl polymer chain, then, because there are 2n double bonds per n divinyl monomers, the number of double bond residues per chain will on average be 2n/(n+1) which will tend towards 2 as the molecular weight increases.
  • the process makes a range of products which, depending on the conditions, can include low molecular weight products (the smallest being the product containing just one DVM, i.e.
  • the vinyl chain length is 1) up to high molecular weight products.
  • the product mixture is purified, and how it is purified, will of course affect the composition of the product and accordingly the length of vinyl polymer chains present.
  • the average vinyl polymer chain length in the resultant purified product may be higher.
  • the product may contain a large amount of divinyl monomer residues wherein one of the double bond residues is capped with a chain transfer agent (as opposed to being part of a chain), i.e. has a nominal chain length of 1.
  • the other double bond residues of those divinyl monomer residues may be part of a longer chain. This may be the most common form of the vinyl residue in the product.
  • the most common vinyl “chain” is that which contains only one divinyl monomer residue.
  • the two most common vinyl chains are (i) the vinyl “chain” which contains only one divinyl monomer residue and (ii) a vinyl chain which contains an integer selected from between 2 and 8, e.g. between 2 and 7, e.g. between 2 and 6, e.g. between 3 and 8, e.g. between 3 and 7, e.g. between 3 and 6, e.g. between 3 and 5, e.g.4 or 5, e.g.5, divinyl monomer residues.
  • the most common vinyl “chain” is that which contains only one divinyl monomer residue, and the second most common vinyl chain contains an integer selected from between 2 and 8, e.g.
  • the distribution of chain lengths may be bimodal, e.g. the maxima may be at chain length 1 and at a second chain length which may optionally be between 3 and 8, e.g. between 3 and 7, e.g. between 3 and 6, e.g. between 3 and 5, e.g.4 or 5, e.g.5, divinyl monomer residues.
  • the distribution of chain lengths may be bimodal, e.g. the maxima may be at chain length 1 and at a second chain length which may optionally be between 3 and 8, e.g. between 3 and 7, e.g. between 3 and 6, e.g. between 3 and 5, e.g.4 or 5, e.g.5.
  • Extent of vinyl polymerisation when using trivinyl monomers The number of propagation steps (i.e.
  • 90 % of the vinyl polymer chains contain fewer than 8 TVM residues, or 90% have a length of 5 or fewer, or 90% have a length of 4 or fewer, or 95% have a length of 10 or fewer, or 95% have a length of 8 or fewer, or 95% have a length of 5 or fewer, or 75% have a length of 8 or fewer, or 75% have a length of 6 or fewer, or 75% have a length of 4 or fewer, or 75% have a length of 3 or fewer, or 75% have a length of 2 or fewer.
  • the average vinyl polymer chain length, or kinetic chain length, in a scenario which assumes that there is no intramolecular reaction can be calculated as follows. If, as discussed above there are 2n+1 chain transfer agent moieties per n trivinyl monomer moieties, and one chain transfer agent per vinyl polymer chain, then, because there are 3n double bonds per n trivinyl monomers, the number of double bond residues per chain will on average be 3n/(2n+1) which will tend towards 1.5 as the molecular weight increases.
  • the process makes a range of products which, depending on the conditions, can include low molecular weight products (the smallest being the product containing just one TVM, i.e.
  • the vinyl chain length is 1) up to high molecular weight products.
  • the product mixture is purified, and how it is purified, will of course affect the composition of the product and accordingly the length of vinyl polymer chains present.
  • the average vinyl polymer chain length in the resultant purified product may be higher.
  • the product may contain a large amount of trivinyl monomer residues wherein two of the double bond residues are capped with a chain transfer agent (as opposed to being part of a chain), i.e. have a nominal chain length of 1.
  • the other double bond residues of those trivinyl monomer residues may be part of a longer chain. This may be the most common form of the vinyl residue in the product.
  • the most common vinyl “chain” is that which contains only one trivinyl monomer residue.
  • the two most common vinyl chains are (i) the vinyl “chain” which contains only one trivinyl monomer residue and (ii) a vinyl chain which contains an integer selected from between 2 and 7, e.g. between 2 and 6, e.g. between 2 and 5, e.g. between 3 and 7, e.g. between 3 and 6, e.g. between 3 and 5, e.g.3 or 4, e.g.3 or e.g.4, trivinyl monomer residues.
  • the most common vinyl “chain” is that which contains only one trivinyl monomer residue, and the second most common vinyl chain contains an integer selected from between 2 and 7, e.g.
  • the distribution of chain lengths may be bimodal, e.g. the maxima may be at chain length 1 and at a second chain length which may optionally be between 3 and 7, e.g. between 3 and 6, e.g. between 3 and 5, e.g.3 or 4, e.g.3 or e.g.4.
  • Extent of vinyl polymerisation when using tetravinyl monomers The number of propagation steps (i.e.
  • Optionally 90 % of the vinyl polymer chains contain fewer than 6 tetravinyl monomer residues, or 90% have a length of 4 or fewer, or 90% have a length of 3 or fewer, or 90% have a length of 2 or fewer, or 95% have a length of 8 or fewer, or 95% have a length of 6 or fewer, or 95% have a length of 4 or fewer, or 95% have a length of 3 or fewer, or 75% have a length of 5 or fewer, or 75% have a length of 4 or fewer, or 75% have a length of 3 or fewer, or 75% have a length of 2 or fewer.
  • the average vinyl polymer chain length, or kinetic chain length, in a scenario which assumes that there is no intramolecular reaction can be calculated as follows. If, as discussed above there are 3n+1 chain transfer agent moieties per n tetravinyl monomer moieties, and one chain transfer agent per vinyl polymer chain, then, because there are 4n double bonds per n tetravinyl monomers, the number of double bond residues per chain will on average be 4n/(3n+1) which will tend towards 1.33 as the molecular weight increases.
  • the process makes a range of products which, depending on the conditions, can include low molecular weight products (the smallest being the product containing just one tetravinyl monomer residue i.e. wherein the vinyl chain length is 1) up to high molecular weight products.
  • low molecular weight products the smallest being the product containing just one tetravinyl monomer residue i.e. wherein the vinyl chain length is 1
  • high molecular weight products the average vinyl polymer chain length in the resultant purified product may be higher.
  • the product may contain a large amount of tetravinyl monomer residues wherein three of the double bond residues are capped with a chain transfer agent (as opposed to being part of a chain), i.e. have a nominal chain length of 1.
  • the other double bond residues of those tetravinyl monomer residues may be part of a longer chain.
  • This may be the most common form of the vinyl residue in the product.
  • the most common vinyl “chain” is that which contains only one tetravinyl monomer residue.
  • the two most common vinyl chains are (i) the vinyl “chain” which contains only one tetravinyl monomer residue and (ii) a vinyl chain which contains an integer selected from between 2 and 6, e.g.
  • the most common vinyl “chain” is that which contains only one tetravinyl monomer residue
  • the second most common vinyl chain contains an integer selected from between 2 and 6, e.g. between 2 and 5, e.g. between 2 and 4, e.g. between 3 and 6, e.g. between 3 and 5, e.g.3 or 4, e.g.3 or e.g.4, tetravinyl monomer residues.
  • the distribution of chain lengths may be bimodal, e.g. the maxima may be at chain length 1 and at a second chain length which may optionally be between 3 and 6, e.g. between 3 and 5, e.g.3 or 4, e.g.3 or e.g.4.
  • Extent of vinyl polymerisation when using multivinyl monomers in general Numerical relationships and theoretical assessments have been presented above for each of divinyl monomers, trivinyl monomers and tetravinyl monomers.
  • the average number of multivinyl monomer residues per vinyl polymer chain may be as follows, where the product contains n multivinyl monomer residues:
  • the average vinyl polymer chain length may contain the following number of multivinyl monomer residues: between 1 and 3, between 1 and 2.5, between 1 and 2.2, between 1 and 2, between 1.1 and 2, between 1.2 and 2, between 1.3 and 2, between 1.33 and 2, between 1.5 and 2, between 1.8 and 2, between 1.9 and 2, between 1.95 and 2, between 1.2 and 1.5, between 1.3 and 1.5, between 1.4 and 1.5, between 1.45 and 1.5, between 1.1 and 1.4, between 1.2 and 1.4, between 1.2 and 1.33, or between 1.3 and 1.33. Whilst the average may optionally be between 1 and 3, a small number of vinyl polymer chains may contain significantly more multivinyl monomer residues, for example as many as 3, 5, 8, 10, 15, 18, 20 or more.
  • Optionally 90 % of the vinyl polymer chains contain fewer than 10 multivinyl monomer residues, or 90% have a length of 7 or fewer, or 90% have a length of 5 or fewer, or 90% have a length of 4 or fewer, or 90% have a length of 3 or fewer, or 90% have a length of 2 or fewer, or 95% have a length of 15 or fewer, or 95% have a length of 10 or fewer, or 95% have a length of 7 or fewer, or 95% have a length of 5 or fewer, or 95% have a length of 4 or fewer, or 95% have a length of 3 or fewer, or 75% have a length of 10 or fewer, or 75% have a length of 7 or fewer, or 75% have a length of 5 or fewer, or 75% have a length of 4 or fewer, or 75% have a length of 3 or fewer, or 75% have a length of 10 or fewer, or 75% have a length of 7 or fewer,
  • the product may contain a large amount of multivinyl monomer residues wherein all but one of the double bond residues in the multivinyl monomer residue is capped with a chain transfer agent (as opposed to being part of a chain), i.e. has a nominal chain length of 1.
  • the remaining double bond residue of the multivinyl monomer residues may be part of a longer chain. This may be the most common form of the vinyl residue in the product.
  • the most common vinyl “chain” is that which contains only one multivinyl monomer residue.
  • the two most common vinyl chains are (i) the vinyl “chain” which contains only one multivinyl monomer residue and (ii) a vinyl chain which contains an integer selected from between 2 and 8, e.g.
  • the most common vinyl “chain” is that which contains only one multivinyl monomer residue, and the second most common vinyl chain contains an integer selected from between 2 and 8, e.g. between 2 and 7, e.g. between 2 and 6, e.g. between 2 and 5, e.g. between 3 and 8, e.g. between 3 and 7, e.g. between 3 and 6, e.g. between 3 and 5, e.g.3, e.g.4 or e.g.5 multivinyl monomer residues.
  • the most common vinyl “chain” is that which contains only one multivinyl monomer residue
  • the second most common vinyl chain contains an integer selected from between 2 and 8, e.g. between 2 and 7, e.g. between 2 and 6, e.g. between 2 and 5, e.g. between 3 and 8, e.g. between 3 and 7, e.g. between 3 and 6, e.g.
  • the distribution of chain lengths may be bimodal, e.g. the maxima may be at chain length 1 and at a second chain length which may optionally be between 3 and 8, e.g. between 3 and 7, e.g. between 3 and 6, e.g. between 3 and 5, e.g.3, 4 or 5.
  • Source of radicals The source of radicals may be an initiator such as azoisobutyronitrile (AIBN).
  • AIBN azoisobutyronitrile
  • the amount used relative to divinyl monomer may be 0.001 to 1, 0.01 to 0.1, 0.01 to 0.05, 0.02 to 0.04 or approximately 0.03 equivalents.
  • a solvent such as for example toluene may be used.
  • the amount of CTA in the product can decrease. Without wishing to be bound by theory, this may be because at greater dilution intramolecular reaction is more likely, meaning that, effectively, reaction of the molecule with itself takes the place of reaction of the molecule with a CTA molecule. Accordingly, this can alter the numerical relationships discussed above, because these assume a theoretical situation in which there is no intramolecular reaction. This provides a further way of controlling the chemistry and tailoring the type of product and its properties.
  • branched polymers may comprise divinyl monomer residues and chain transfer residues, wherein the molar ratio of chain transfer residues to divinyl monomer residues is between 0.5 and 2.
  • the ratio is optionally between 0.7 and 1.5, optionally between 0.75 and 1.3, optionally between 0.8 and 1.2, optionally between 0.9 and 1.1, optionally between 1 and 1.05, optionally approximately 1.
  • Some of the vinyl polymer chains may contain as many as 18, or 15, divinyl monomer residues. Only a small proportion are this long, however: the average, for high molecular weight materials, may be around 2.
  • Optionally 90 % of the vinyl polymer chains contain fewer than 10 DVM residues, or 90% have a length of 7 or fewer, or 90% have a length of 5 or fewer, or 95% have a length of 15 or fewer, or 95% have a length of 10 or fewer, or 95% have a length of 7 or fewer, or 75% have a length of 10 or fewer, or 75% have a length of 7 or fewer, or 75% have a length of 5 or fewer, or 75% have a length of 4 or fewer, or 75% have a length of 3 or fewer).
  • the branched polymer product may comprise divinyl monomer residues and chain transfer residues, wherein 90 % of the vinyl polymer chains contain fewer than 10 DVM residues, or 90% have a length of 7 or fewer, or 90% have a length of 5 or fewer, or 95% have a length of 15 or fewer, or 95% have a length of 10 or fewer, or 95% have a length of 7 or fewer, or 75% have a length of 10 or fewer, or 75% have a length of 7 or fewer, or 75% have a length of 7 or fewer, or 75% have a length of 5 or fewer, or 75% have a length of 4 or fewer, or 75% have a length of 3 or fewer).
  • each vinyl residue may be directly linked to 0, 1 or 2 other vinyl residues as closest neighbours.
  • the branched polymer comprises divinyl monomer residues and chain transfer residues, wherein each vinyl residue is directly vinyl polymerised to on average 0.5 to 1.5 other divinyl monomer residue.
  • this may be 0.8 to 1.2, 0.8 to 1.1, 0.9 to 1, or approximately 1, on average.
  • the polymers are characterised by having a large amount of chain transfer agent incorporation, and also by having short distinct vinyl polymer chains.
  • a vinyl polymer chain will normally comprise a long saturated backbone, during the preparation of the present polymers - even though they are built up using vinyl polymerisation - most of the double bonds only react with one other double bond, or react with no other double bonds, rather than react with two other double bonds.
  • the branched polymer may comprise divinyl monomer residues and chain transfer residues, in which there is a multiplicity of vinyl polymer chain segments having an average length of between 1 and 3 divinyl monomer residues.
  • the average length may be between 1 and 2.5, between 1 and 2.2, between 1 and 2, between 1.3 and 2, between 1.5 and 2, between 1.7 and 2, between 1.8 and 2, between 1.9 and 2, between 1.95 and 2, or approximately 2.
  • the skilled person will understand how the number of double bond residues affects the carbon chain length of the resultant vinyl polymer segment.
  • a polymer chain segment comprises 2 double bond residues
  • this equates to a saturated carbon chain segment of 4 carbon atoms.
  • the incorporation of monovinyl monomers as well as divinyl monomers may affect the average vinyl chain length but does not affect the average number of divinyl monomer residues per chain. It can be a way of increasing the vinyl chains without increasing branching.
  • the branched polymer may comprise divinyl monomer residues and chain transfer residues wherein the divinyl monomer residues comprise less than 20mol% double bond functionality. In other words, in such polymer products, at least 80% of the double bonds of the divinyl monomers have reacted to form saturated carbon-carbon chains.
  • the residues may comprise less than 10mol%, or less than 5mol%, or less than 2mol%, or less than 1mol%, or substantially no, double bond functionality.
  • Another way of defining the polymer is in terms of its Mark Houwink alpha value. Optionally, this may be below 0.5.
  • the above description of polymer products relates in particular to those containing divinyl monomer residues.
  • polymer products containing other multivinyl monomer residues may include for example trivinyl monomer residues and/or tetravinyl monomer residues. Definitions and disclosures herein apply mutatis mutandis.
  • the molar ratio, on average, of chain transfer residues to multivinyl monomer residues may optionally be: - for multivinyl monomers generally: between 0.5 and 6, between 0.7 and 4.5, between 0.75 and 3.9, between 0.8 and 3.6, between 0.9 and 3.3, between 1 and 3.15, or between approximately 1 and approximately 3; - for trivinyl monomers: between 1 and 4, between 1.4 and 3, between 1.5 and 2.6, between 1.6 and 2.4, between 1.8 and 2.2, between 2 and 2.1, or approximately 2; - for tetravinyl monomers: between 1.5 and 6, between 2.1 and 4.5, between 2.25 and 3.9, between 2.4 and 3.6, between 2.7 and 3.3, between 3 and 3.15, or approximately 3.
  • - for multivinyl monomers generally: 90 % of the vinyl polymer chains contain fewer than 10 multivinyl monomer residues, or 90% have a length of 7 or fewer, or 90% have a length of 5 or fewer, or 90% have a length of 4 or fewer, or 90% have a length of 3 or fewer, or 90% have a length of 2 or fewer, or 95% have a length of 15 or fewer, or 95% have a length of 10 or fewer, or 95% have a length of 7 or fewer, or 95% have a length of 5 or fewer, or 95% have a length of 4 or fewer, or 95% have a length of 3 or fewer, or 75% have a length of 10 or fewer, or 75% have a length of 7 or fewer, or 75% have a length of 5 or fewer, or 75% have a length of 4 or fewer, or 75% have a length of 3 or fewer, or 75% have a length of 10 or fewer, or 75% have
  • the branched polymer product comprises a multiplicity of vinyl polymer chain segments having an average length of: - for multivinyl monomers generally: between 1 and 3, between 1 and 2.5, between 1 and 2.2, between 1 and 2, between 1.1 and 2, between 1.2 and 2, between 1.3 and 2, between 1.33 and 2, between 1.5 and 2, between 1.8 and 2, between 1.9 and 2, between 1.95 and 2, between 1.2 and 1.5, between 1.3 and 1.5, between 1.4 and 1.5, between 1.45 and 1.5, between 1.1 and 1.4, between 1.2 and 1.4, between 1.2 and 1.33, or between 1.3 and 1.33 multivinyl monomer residues; - for trivinyl monomers: between 1 and 2, between 1 and 1.8, between 1 and 1.7, between 1 and 1.5, between 1.1 and 1.5, between 1.2 and 1.5, between 1.25 and 1.5, between 1.3 and 1.5, between 1.4 and 1.5, or between 1.45 and 1.5, or of approximately 1.5, trivinyl monomer residues; - for tetravinyl monomers: between 1 and 1.1
  • a branched polymer product comprises multivinyl monomer residues and chain transfer residues wherein the multivinyl monomer residues comprise less than 20mol% double bond functionality.
  • the residues may comprise less than 10mol%, or less than 5mol%, or less than 2mol%, or less than 1mol%, or substantially no, double bond functionality.
  • Figures 1 to 12 show fragments of branched polymers in accordance with the present invention, each of which is prepared by the co-polymerisation of one or more divinyl monomer and a monovinyl monomer using one or more chain transfer agent, wherein said monovinyl monomer carries a curable functional group;
  • the example structures shown in figures 1 to 12 are the result of using: - as chain transfer agent: o dodecane thiol (DDT) (figures 1 to 5, 7, 8 and 10 to 12), o dodecane thiol in combination with thiolglycerol (TG) (figure 6), o cyclohexanethiol (CHT) (figure 9) - as divinyl monomer (DVM): o ethylene glycol dimethacrylate (EGDMA) (exclusively in figures 1, 4 and 9; and in combination with other divinyl monomers
  • DDT dodecane thiol
  • TG thiolglycerol
  • Figures 13 to 15 show IR spectra of resins in accordance with the present invention
  • Figures 16 to 20 show stress-strain curves for resins prepared in accordance with the present invention
  • Figure 21 shows reusable thermoset behaviour wherein a thermoset resin of the present invention is ground and recured twice
  • Figure 22 shows a cured thermoset resin of the present invention in the form of a disc
  • Figure 23 shows stress relaxation behaviour and an Arrhenius plot in respect of a product of the present invention
  • Figure 24 shows dog bone moulds which have been cured and tested, ground down, remoulded and retested
  • Figures 25 to 29 show flexible dog bone specimens, the manipulation of these, broken specimens, once-recycled specimens and twice-recycled specimens
  • Figures 30 to 32 show stress-strain curves for the specimens of Figures 25, 28 and 29 respectively, and Figures 33 to 37 show the shape memory behaviour of specimens.
  • branched polymer carrying curable functional groups used in recyclable thermosets
  • An example of a branched polymer carrying curable functional groups in accordance with the present invention is an epoxy polymer (“Polymer 1”) prepared by the transfer- dominated branching radical telomerisation of a divinyl monomer in the presence of an epoxy-carrying monovinyl monomer and in the presence of a chain transfer agent.
  • the divinyl monomer is urethane dimethacrylate (UDMA)
  • the monovinyl monomer is glycidyl methacrylate (GlyMA or GMA)
  • the chain transfer agent is dodecane thiol, in a ratio of 1:1:1.
  • FIG. 7 An example fragment of this epoxy polymer is illustrated in figure 5.
  • a related example (figure 7) uses methacrylic acid (MA) instead of glycidyl methacrylate.
  • Copolymerisation of UDMA with GMA (to make epoxy polymer (Polymer 1)) or MA (to make corresponding carboxyl polymer) Diurethane dimethacrylate (1 g, 2.13 mmol), 1-dodecanethiol (0.43 g, 2.13 mmol), AIBN (0.0157 g, 0.096 mmol), glycidyl methacrylate (0.32 g, 2.13mmol) or methacrylic acid (0.18 g, 2.13mmol) and ethyl acetate (17.28 mL, if using glycidyl methacrylate; or 16.09 mL, if using methacrylic acid) were added to a 50 mL round-bottomed flask and purged with nitrogen for 15 minutes.
  • the cured discs were then broken and ground down to a powder using a coffee grinder and pestle and mortar.
  • the discs were reformed using the 20 mm disc mould and MeltPrep by heating to 250 oC for 30 minutes.
  • the resulting vitrimer disc was submerged in THF for 24 hours to ensure the disc swelled and did not dissolve.
  • Auto cured disc of CHT/UDMA/GMA copolymer is shown in Fig.22.
  • the powder was added to a 20mm disc mould and cured samples were manufactured using a MeltPrep hot melt extrusion machine.
  • the mould was heated to 180 oC for 30 minutes and then heated to 250 oC for a further 30 minutes. Cured disc were obtained and the extent of cure was monitored by FTIR.
  • the 20mm discs described above were subjected to stress relaxation tests using a rheometer. Using a 20mm flat plate geometry, a constant strain of 1% was maintained at an initial force of 10N over temperature ranging from 210 oC to 240 oC until 37% stress relaxation has been reached. The time at 37% stress relaxation was plotted in an Arrhenius plot from which the activation energy could be calculated.
  • Fig.23 a shows normalized stress relaxation plotted against time (CHT/UDMA/GMA cured with 1:1 mol ratio of DDT/UDMA/MA. Specimen subjected to stress relaxation experiments, at 210, 220, 230 and 240 oC.) The time at each temperature to reach 37% of stress relaxation was plotted in an Arrhenius plot (Fig.24 b)). From the gradient of the plot the activation energy can be calculated as 115.74 KJ/mol.
  • the mould was sandwiched between two 20 x 20 cm sheets of stainless steel and put into a hot press at 200 °C for 20 minutes. The mould was allowed to cool and the specimen was retrieved. Once cured specimen had been tested for tensile strength, they were ground using a coffee grinder and a pestle and mortar.
  • the epoxy-containing polymers were cured with an acid containing polymer, with methacrylic acid as monofunctional monomer or 3-mercaptopropionic acid as CTA or a small molecule diacid, sebacic acid, to form hydroxyesters which we believe then react with further epoxy groups resulting in complete cure of the network and full reaction of epoxy groups as visualised in FTIR.
  • IR spectra indicated the reaction of curable functional groups after curing and also after re- curing.
  • Figure 13 shows the disappearance of the epoxy peak after “auto” curing of the epoxy-functional polymer (Polymer 1).
  • One of the traces refers to the neat uncured sample showing epoxy peak at 908 cm -1 .
  • Two further traces relate to FTIR spectra performed during curing to check when full cure is reached, and a further trace (the lowest trace) indicates when that full cure has been reached, as visualized by disappearance of peak at 908cm -1 .
  • Figure 14 shows disappearance of the epoxy peak after curing of epoxy- functional polymer (Polymer 1) with Polymer 2, an acid functional polymer (DDT/UDMA/MA copolymer).
  • FIG. 15 shows disappearance of the epoxy peak after curing of an epoxy- functional polymer (Polymer 3) (DDT/GDMA wherein GDMA is glycerol dimethacrylate).
  • Polymer 3 DDT/GDMA wherein GDMA is glycerol dimethacrylate.
  • the hydroxy groups attacks epoxy to ring open to form insoluble cured network.
  • the resins exhibited resuable thermoset behaviour. After curing, grinding they could be recured to materials with substantially the same properties. A further cycle of grinding and recuring retained substantially the same properties. Physical properties, including tensile strength, of the recyclable thermosets were investigated.
  • Various systems were investigated, including those using GlyMA as epoxy-functional monovinyl monomer, CHT (cyclohexane thiol) as CTA, and EGDMA and/or UDMA as multivinyl monomer:
  • M0 refers to the acid containing polymer DDT/EGDMA/MA described above.
  • Stress-strain curves for the resultant resins are shown in Figure 16.
  • Fig 16a refers to G0
  • Fig 16b refers to G50
  • Fig 16c refers to G100.
  • some traces represent the stress-strain curves for the cured dog bone mold and some traces represent the tested, ground and remolded dog bone mold.
  • cyclohexanethiol is used as the CTA.
  • Stress-strain curves are also shown for other resins in Figures 17 to 20.
  • Figure 17 relates to the stress-strain curves of an epoxy/acid cure of DDT/UDMA/GMA (Polymer 1) and DDT/UDMA/MA (Polymer 4). This is a comparison to Fig 16c in that only UDMA is present in the polymer composition.
  • the solid lines refer to the stress-strain curves of the cured samples and the dashed lines refer to the stress-strain curves of the tested, ground and remolded samples of previous.
  • thermoset resins of the present invention may optionally be flexible thermosets.
  • a polymer with a composition of 1:1:1 of dodecanthiol: diurethane dimethacrylate: glycidyl methacrylate was prepared via TBRT. T g was measured at -1 °C by DSC. The polymer was partially cured by heating via hotplate to 250 °C for -10 minutes to increase the T g in order to add sample to vacuum compression mould. Polymer was added to vacuum compression mould and heated to 250 °C at 1 bar for 30 minutes to produce thermoset dog bone specimens (Fig.25).
  • Dog bone specimens were flexible and could be easily manipulated (Fig.26). Dog bone specimens were then subjected to tensile strength measurements using a universal testing machine to ascertain Young's modulus and elongation at break (Fig.30). Recycling 1 Previous tensile strength test produced broken dog bone specimens (Fig.27). Broken specimens were re-inserted into dog bone mould and healed to 250 °C at 1 bar for 30 minutes using vacuum compression to heal broken specimens and regain dog bone (Fig.28). Recycled dog bone specimens were then subjected to tensile strength measurements using a universal testing machine to ascertain Young's modulus and elongation at break (Fig.31).
  • Specimen was then heated in set conformation again to 200 °C for 20 minutes using a hotplate and allowed to cool to room temperature to produce a permanent shape (Fig 36).
  • the permanent shape was then placed in 50 °C water bath for 5 minutes and left to cool to room temperature to produce (Fig.37).

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Abstract

Une composition thermodurcissable recyclable comprend un polymère qui est un polymère vinylique ramifié préparé par télomérisation radicalaire à ramification dominée par transfert (TBRT) de monomères multivinyliques et éventuellement de monomères monovinyliques en présence d'agents de transfert réversible, ledit polymère comprenant un ou plusieurs groupes fonctionnels durcissables, ledit ou lesdits groupes fonctionnels durcissables étant choisis parmi : un groupe époxy; un groupe acide ou une autre fonctionnalité carboxyle ou acyle réactive; un groupe hydroxy ou un groupe hydroxy activé; un groupe isocyanate ou un groupe isocyanate bloqué; ou un groupe amine. Le recyclage peut consister à réaliser un re-durcissage à l'aide de chaleur, et éventuellement à décomposer physiquement la résine thermodurcissable recyclable avant ledit re-durcissage à l'aide de chaleur.
PCT/GB2023/051398 2022-05-31 2023-05-26 Résines thermodurcissables recyclables Ceased WO2023233132A1 (fr)

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WO2011029579A2 (fr) * 2009-09-08 2011-03-17 Unilever Plc Utilisation de polymeres
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WO2018197885A1 (fr) 2017-04-26 2018-11-01 The University Of Liverpool Polymères ramifiés
WO2018197884A1 (fr) 2017-04-26 2018-11-01 The University Of Liverpool Polymères
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WO2011029579A2 (fr) * 2009-09-08 2011-03-17 Unilever Plc Utilisation de polymeres
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WO2018197885A1 (fr) 2017-04-26 2018-11-01 The University Of Liverpool Polymères ramifiés
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