WO2002024773A2 - Branched polymers, method for the production thereof, and their use - Google Patents

Abstract

The invention relates to a polymer that can be obtained by radically polymerizing at least one monomer of general formula (I), wherein: R1 represents an alkylene radical having 1 to 44 C atoms, a cycloalkylene radical having 3 to 44 C atoms, an arylene radical having 4 to 40 C atoms, an aralkylene radical having 5 to 40 C atoms or a heteroaryl radical having 4 to 40 C atoms; R?2, R3 and R4¿, independent of one another, represent H or an alkyl radical having 1 to 10 C atoms or an aryl radical having 4 to 12 C atoms, and; Z represents a substituent having at least one thermally induced homolytically cleavable bond, whereby the thermally induced homolytic cleaving of the bond in Z occurs at a temperature ranging from - 10 °C to 150 °C. The invention also relates to a method for producing the aforementioned polymer and to the use thereof.

Description

 Branched polymers, processes for their preparation and their use

The invention relates to a polymer obtainable by radical polymerization of monomers of the general formula I.

in which R ^{1 is} an alkylene radical having 1 to 44 C atoms, a cycloalkylene radical having 3 to 44 C atoms, an arylene radical having 4 to 40 C atoms, an aralkylene radical having 5 to 40 C atoms or a heteroaryl radical having 4 up to 40 carbon atoms, R, R and R each independently of one another for H or an alkyl radical having 1 to 10 carbon atoms or an aryl radical with 4 to 12 carbon atoms and Z for a substituent with at least one thermally or by redox initiators induces homolytically cleavable bond, the homolytic cleavage of the bond in Z taking place at a temperature of from -10 ° C. to 150 ° C.

Highly branched polymers and polymeric core-shell structures are of great academic and industrial interest. For example, in the case of a molecular weight identical to that of non-branched polymers, highly branched polymers show a considerably reduced intrinsic viscosity and often a significantly better solubility. This means, for example, that materials to which highly branched polymers have been mixed are easier to process from the melt or from the solution.

Polymer core-shell structures can be used, for example, as impact modifiers in polymer materials. Rubber-like polymers with a glass transition temperature of less than 0 ° C are used as the core. det, which carry a polymer as a shell, which enables mixing into the hard polymer matrix. Modified in this way, the properties can be combined hard and tough in one material.

The synthesis of highly branched polymers often only succeeds through the polycondensation or polyaddition of AB ₂ monomers (PJ Flory, JACS 74, 2718 (1952)) or via protective group chemistry. Numerous polyesters, polyethers and polyamides were thus produced according to the pattern described above (M. Johansson, E. Malmstroem, A. Hult, J. Polym. Sei. Part A; Polym. Chem. 31, 619 (1993); KE Uhrich, CJ Hawker, JMJ Frechet, SR Turner, Macromolecules 25, 4583 (1992); KE Uhrich, S. Boegemann, JMJ Frechet, SR Turner, Polym. Bull. 25, 551 (1991)). However, these processes are too time-consuming and costly to be able to utilize them technically.

Highly branched polymers are not perfectly structured structures, i.e. H. they have a degree of branching of less than 100%. Perfect structures with a degree of branching of 100% are called dendrimers. In contrast to the highly branched polymers, dendrimers are monodisperse.

More recently, ner processes for the production of highly branched vinyl polymers have also been presented. The first ner driving was the self-condensing vinyl polymerization of 3- (l-chloroethyl) ethenylbenzene (JMJ Frechet, M. Henmi, I. Gitsov, S. Aoshima, MR Leduc, B. Grubbs, Science 269), which followed a living cationic mechanism , 1080 (1995)). The formation of highly branched polymers is also possible through living radical polymerization. The TEMPO (CJ Hawker, JMJ Frechet, RB Grubbs, J. Dao JACS 117, 763 (1995)) and the ATRP method (SG Gaynor, S. Edelmann, K. Matyjaszewski, Macromolecules 29, 1079 (1996) are described ). However, these recently introduced systems have the disadvantage that the products are contaminated with toxic heavy metals, or that the synthesis methods place very high demands on the purity of the chemical substances used. Both prevent a technical or commercial use.

For the synthesis of core-shell structures, for example, grafting reactions or the copolymerization of monomers with macromonomers (M. Akashi, I. Kirikihira, N. Miyauchi, Angew. Makromol. Chem. 132, 81 (1985)). Technically, core-shell polymers are produced, for example, by prepolymerizing butadiene as a polybutadiene dispersion, which is mixed with styrene and acrylonitrile and polymerized in a further cascade-like system (Adolf Echte, "Handbuch der Technischen Polymerchemie", p. 490 ff., VCH Verlagsgesellschaft mbH, Weinheim, 1993).

In the graft copolymerizations, a distinction is made between grafting from the backbone of the polymer ("grafting from") and grafting onto the polymer backbone ("grafting onto"). When "grafting from", suitable initiator groups must be linked to the polymer backbone (O. Nuyken, B. Voit, "Polymeric Azo Initiators" in Macromolecular Design: Concept and Practice, ed. MK Mishra, Polymer Frontiers International, Inc., Hopewell Jet. (New York), New Delhi (1994); A. Useda, S. Nagai, "Macroinitiators including syntheses and applications of block copolymers derived therefirom" in Macromolecular Design: Concept and Practice, ed. MK Mishra, Polymer Frontiers International, Inc., Hopewell Jet. (New York), New Delhi (1994)). The "grafting from" method has the great advantage over all other methods that no homopolymers are formed. At the same time, however, this method is very limited because crosslinking reactions occur very quickly. These cross-linking reactions can be partially prevented if special precautionary measures are taken.

The polymerization leading to graft copolymers can be carried out, for example, according to the catalytic mechanism (Y. Jing, JMJ Frechet, Polym. Prepr. 30 (1), 127 (1989)). Cationic polymerization, however, is particularly sensitive to impurities, such as water, and is therefore hardly technically feasible. On the other hand, the polymerization can also be carried out using a living radical mechanism (for example RAFT) (SG Gaynor, P. Balchandani, A. Kulfan, M. Podwika, K. Matyjaszewski, Polym. Prepr. 38 (1), 496, (1997) ). This method, on the other hand, has the serious disadvantages that, on the one hand, toxic heavy metals remain in the product and, on the other hand, the monomer selection for the grafting reaction is very limited. Another problem with these syntheses, particularly in the synthesis of amphiphilic structures, is the poor solubility of the monomer in the polymer to be grafted or the poor solubility of the polymers in one another (M. Akashi, I. Yamashita, N. Miyauchi, Angew. Makromol. Chem. 122 , 147 (1984)).

K. Ishizu and A. Mori describe the preparation of highly branched polymers by self-adding free radical vinyl polymerization of photofunctional styrene derivatives (K. Ishizu, A. Mori, Macromol. Rapid Commun. 21, 10, 665 f.). The publication describes the radical polymerization of N, N-diethylaminodithiocarbamoylmethylstyrene under UV radiation. A disadvantage of the method described is that it is not possible to work with conventional reactors and, moreover, the reaction can only be carried out with great effort for cleaning and keeping the reactants clean. Furthermore, the yields achieved are low. The publication does not say anything about the production of core-shell polymers.

The object of the present invention is therefore to provide polymers which do not have the disadvantages of the prior art. In particular, the invention has for its object to provide highly branched polymers and core-shell polymers in a simple manner.

This object is achieved by means of polymers as described further on in this text, processes for producing these polymers and their use.

The present invention therefore relates to a polymer which can be obtained by radical polymerization of at least one monomer of the general formula I.

worin R¹ für einen Alkylenrest mit 1 bis 44 C-Atomen, einen Cycloalkylenrest mit 3 bis 44 C-Atomen, einen Arylenrest mit 4 bis 40 C-Atomen, einen Aralky- lenrest mit 5 bis 40 C-Atomen oder einen Heteroarylrest mit 4 bis 40 C-Atomen, R , R und R jeweils unabhängig voneinander für H oder einen Alkylrest mit 1 bis 10 C-Atomen oder einen Arylrest mit 4 bis 12 C-Atomen und Z für einen Substituenten mit mindestens einer thermisch oder durch Redoxinitiatoren induziert homolytisch spaltbaren Bindung steht, wobei die homolytische Spaltung der Bindung in Z bei einer Temperatur von -10°C bis 150°C erfolgt.

in which R ^{1 is} an alkylene radical having 1 to 44 C atoms, a cycloalkylene radical having 3 to 44 C atoms, an arylene radical having 4 to 40 C atoms, an aralkylene radical having 5 to 40 C atoms or a heteroaryl radical having 4 to 40 C atoms, R, R and R each independently of one another for H or an alkyl radical with 1 to 10 C atoms or an aryl radical with 4 to 12 C atoms and Z for a substituent with at least one thermally or induced by redox initiators homolytically cleavable bond is, the homolytic cleavage of the bond in Z takes place at a temperature of -10 ° C to 150 ° C.

A polymer according to the present invention is produced by radical polymerization of at least one monomer of the general formula I.

In the general formula I, the R ¹ radical is, for example, an alkylene radical having 1 to about 44 C atoms. In the context of a preferred embodiment of the present invention, however, the alkylene radical has more than 1 carbon atom, for example at least about 2, 3, 4, 5 or 6 carbon atoms. In the context of a further preferred embodiment, the upper limit for the number of carbon atoms in the R ¹ radical is approximately 30 less, for example 15 to 25. The term “alkylene radical” in the context of the present invention also includes alkylene radicals which have one or more substituents Suitable substituents are, for example, OH groups, amino groups, ester groups, acid groups, epoxy groups and the like, provided that they do not completely prevent the radical polymerization.

In the context of a further embodiment of the present invention, the radical R ^{1 is} a cycloalkylene radical having 3 to about 44 carbon atoms. In a preferred embodiment, the cycloalkylene radical has at least 4, preferably at least 5, carbon atoms. Cyclohexylene radicals are particularly suitable in the context of the present invention. It is provided according to the invention that the radical R ^{1 is} , for example, a cycloalkylene radical. However, it is also possible for the radical R ¹ to stand for a series of cycloalkylene radicals, for example for two cyclohexyl radicals arranged directly one behind the other. If the radical R ^{1 represents} several cycloalkylene radicals, these cycloalkylene radicals can be separated, for example, by alkylene radicals having 1 to 4 carbon atoms, in particular by a CH ₂ group. The cycloalkylene residues can may be substituted. Suitable substituents have already been mentioned in the description of the alkylene radicals.

In the context of a further embodiment of the present invention, the radical R ^{1 is} an arylene radical with 4 to about 40 C atoms, in particular 6 to about 15 C atoms. In the context of a preferred embodiment of the invention, the radical R ^{1 represents} an optionally substituted phenylene radical or a sequence or more phenylene radicals. For the stringing together of several phenylene radicals, what has already been said for the cycloalkylene radicals applies, ie, if appropriate, several phenylene radicals can be separated by one or more alkylene groups. The arylene radicals which can be used as radical R ¹ in the context of the present invention can optionally have substituents. Suitable substituents have already been mentioned in the description of the alkylene radicals.

In a further embodiment of the present invention, the radical R ¹ can be an aralkylene radical having 5 to 40 C atoms or a heteroaryl radical having 4 to about 40 C atoms. The radicals mentioned can optionally be substituted. Suitable substituents have already been mentioned in the description of the alkylene radicals.

The monomer of the general formula I which leads to the polymer according to the invention also has radicals R ² , R ³ and R ⁴ which each independently represent H or an alkyl radical having 1 to 10 C atoms or an aryl radical having 4 to 12 C atoms , In a preferred embodiment of the present invention, the radicals R ² , R ³ and R ^{4 are} H or an alkyl radical having 1, 2, 3 or 4 carbon atoms. In a particularly preferred embodiment of the present invention, at least one, preferably at least two and particularly preferably at least three of the radicals R ² , R ³ and R ^{4 are} H.

The monomers of the general formula I have at least one substituent Z.

Suitable substituents Z are in principle all substituents which have at least one thermally induced homolytically cleavable bond, the thermally induced homolytic cleavage of the bond takes place at a temperature of -10 ° C to 150 ° C.

In principle, suitable substituents Z are all substituents which have a corresponding bond which is homolytically cleavable in the temperature range mentioned above. Suitable bonds, which can be homolytically cleavable within the above-mentioned temperature range, are, for example, C-C or O-O bonds. The bonds generally have to be reduced in their binding energy by suitable substituents to such an extent that cleavage is possible within the above-mentioned temperature range.

The homolytic cleavage of the bond in the Z radical is brought about thermally in the context of the present invention. In the context of a preferred embodiment of the present invention, the radical Z therefore has a C-C bond or an O-O bond.

Suitable Z radicals are derived, for example, from compounds usually used as initiators for free-radical polymerization. For example, alkyl peroxides such as cumyl or t-butyl peroxide or hydroperoxides such as cumyl hydroperoxide or t-butyl hydroperoxide are frequently used to initiate radical polymerizations. Peresters such as t-butyl perbenzoate are also suitable. A radical Z can therefore have a theoretical formula based on these initiators. Suitable Z radicals have, for example, the following structures:

Z =

with R = CH (CH ₃ ) ₂ , CH (CH ₃ ) - C ₂ H ₅ , C ₆ H _π

CH ₃

C O OH

CH ₃

-O- -OH

In the context of a further embodiment of the present invention, the radical Z can be derived, for example, from compounds containing azo groups, such as are often used to initiate radical polymerizations. One of the best known compounds that can be used in this regard is, for example, 2,2'-azobisisobutyronitrile (AIBN). Although such azo compounds do not have as low a binding energy as the peroxo compounds, the driving force for the homolytic cleavage of the CN bond is the formation of the stable nitrogen molecule. Redox initiation by hydroperoxides and metal cations, such as Fe ^2+, should also be mentioned.

In a preferred embodiment, the radical Z therefore represents a radical of the general formula II - N = N - R (II),

wherein R ^{5 represents} a -CN group, a -COOR group or a - for a linear or branched, saturated or unsaturated optionally substituted alkyl radical with 2 to 10 C-atoms, an optionally substituted aryl radical with 6 to 24 C-atoms OC (O) R group, where R is a linear or branched chain aliphatic, aromatic lipatic or aromatic hydrocarbon radical.

Suitable substituents are e.g.

CN,

oder - COOR.

or - COOR.

The radical R ⁵ preferably has a structure which makes it possible to stabilize a radical which forms after the nitrogen elimination, at least for a short time. In a preferred embodiment, therefore, compounds with a Z radical are used which, for example, carry one or more nitrile groups as the R ⁵ radical, so that this R ⁵ radical is not capable of initiation. This prevents the formation of homopolymers. An example of such a residue is:

CN

• C - CH ₃

CN. The following may be mentioned individually as residues (II):

CH ₃

-N = NC CH ₂ CH (CH ₃ ) ₂

CN

-N = N C CN

CN

CH ₃

'N = ^ N- -H

C ₆ H ₅

where R, R 1 and R ₂ each independently represent a linear or branched chain aliphatic, aromatic or araliphatic hydrocarbon radical, methyl, ethyl, propyl, phenyl and benzyl being mentioned for example.

In a further particularly preferred embodiment, a compound is used in the context of the present invention which, as radical Z, is a radical of the general formula III

having.

In the context of the present invention, a polymer according to the invention can be prepared, for example, by polymerizing a single monomer of the general formula I. However, it is also provided in the context of the present invention that a polymer according to the invention is prepared by polymerizing two or more compounds of the general formula I.

In the context of a further embodiment of the present invention, it is possible that in addition to at least one monomer of the general formula I there is also another monomer or a mixture of two or more further monomers which does not correspond to the general formula I.

Suitable further monomers are, for example, the following monomers:

Ci to C ₂₀ alkyl and hydroxy alkyl esters of monoethylenically unsaturated C ₃ to Cio monocarboxylic acids or C ₄ to C ₈ dicarboxylic acids, for example methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate, isobornyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers), 2-ethylhexyl acrylate, isobornyl acrylate, benzyl acrylate, phenyl acrylate, hydroxyl acrylate, styl acrylate, styl acrylate, malyl acrylate, styl acrylate Hydroxybutyl acrylate, furthermore (meth) acrylic esters of alkoxylated Ci to C ₁₈ alcohols, which are reacted with 2 to 50 mol ethylene oxide, propylene oxide, butylene oxide or mixtures thereof; Benzyl methacrylate, phenyl methacrylate, stearyl methacrylate, methacrylonitrile, styrene, α-methylstyrene, acrylonitrile, functionalized methacrylates; Acrylates and styrenes, selected from glycidyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate (all isomers), hydroxybutyl methacrylate (all isomers), dietylaminoethyl methacrylate, triethylene glycol methacrylate, itaconic anhydride, itaconic acid, glycidyl acrylate, trihydroxyethylamyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, tert-butyl methacrylamide, NN-butyl methacrylamide, N-methylol methacrylamide, N-ethylol methacrylamide, N-tert-butyl acrylamide, N-butyl acrylamide, N-methylol acrylamide, N-ethylol acrylamide, vinyl benzoic acid (all isomers), diethylaminostyrene (all isomers), α-methyl vinyl benzoic acid (all isomers), diethylamino-α-methyl styrene (all isomers), p-methyl styrene, p-vinyl benzene sulfonic acid, trimethoxysilyl propyl methacrylate, triethoxysilyl propyl methacrylate, tributoxysilyl propyl methacrylate, di-methoxyl methoxyl methoxyl methoxyl methoxyl methoxyl methoxyl methoxyl methoxyl methoxyl methoxyl methacrylate lylpropylmethacrylat, Diethoxysilylpropyl- methacrylate, Dibutoxysilylpropylmethacrylat, Diisopropoxysilylpropylmethacry- methacrylate, trimethoxysilylpropyl acrylate, Triethoxysilylpropylacrylat, pylacraylat Tributoxysilylpro-, Dimethoxymethylsilylpropylacrylat, lat Diethoxymethylsilylpropylacry-, Dibutoxymethylsilylpropylacrylat, Diisopropoxymethylsilylpropylacrylat, Dimethoxysilylpropylacrylat, Diethoxysilylpropylacrylat, Dibutoxysilylpropylac- triacrylate, Diisopropoxysilylpropylacrylat, vinyl acetate and vinyl butyrate, vinyl chloride, vinyl fluoride, vinyl bromide, Vinyl alcohol, vinyl ethers of - to C ₁₈ alcohols, vinyl ethers of alkoxylated Ci- to Cι- ₈ alcohols and vinyl ethers of polyalkylene oxides such as polyethylene oxide, polypropylene oxide or polybutylene oxide, monoethylenically unsaturated C - to C ₁₀ monocarboxylic acids, their alkali metal salts and / or ammonium salts , for example acrylic acid, methacrylic acid, dimethyl acrylic acid, ethyl acrylic acid, allylacetic acid or vinyl acetic acid, towards monoethylenically unsaturated C ₄ to C ₈ dicarboxylic acids, their half esters, Anhydrides, alkali metal salts and / or ammonium salts, for example maleic acid, fumaric acid, itaconic acid, mesaconic acid, methylene malonic acid, citraconic acid, maleic anhydride, itaconic anhydride or methylmalonic anhydride; further monoethylenically unsaturated monomers containing sulfonic acid groups, for example allylsulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, methallylsulfonic acid, vinyl sulfonic acid, 3-sulfopropyl acrylate or methacrylic acid 3-sulfopropyl ester, furthermore monoethylenically unsaturated monomers containing phosphonic acid groups , for example vinylphosphonic acid, allylphosphonic acid or acrylamidoethylpropanephosphonic acid, furthermore amides and N-substituted amides of monoethylenically unsaturated C ₃ to C ₁₀ monocarboxylic acids or C ₄ to C ₈ dicarboxylic acids, for example acrylamide, N-alkylacrylamides or N, N-dialkylacrylamides each with 1 to 18 carbon atoms in the alkyl group, such as N-methacrylamide, N, N-dimethylacrylamide, N-tert-butylacrylamide or N-octadecylacrylamide, maleic acid monomethylhexylamide, maleic acid mono-cylamide, diethylammopropyl methacrylamide or acrylamidoglycolic acid; further alkylamidoalkyl (meth) acrylates, for example dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, etiiylaininoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate or dimethylaminopropyl methacrylate; furthermore vinyl esters, vinyl formate, vinyl acetate or vinyl propionate, which may also be saponified after the polymerization; furthermore N-vinyl compounds, for example N-vinylpyrrolidone, N-vinylaprolactam, N-vinylformamide, N-vinyl-N-methylformamide, 1-vinylimidazole or 1-vinyl-2-methylimidazole; furthermore vinyl ethers of Ci to C ₁₈ alcohols, vinyl ethers of alkoxylated Ci to C ₁₈ alcohols and vinyl ethers of polyalkylene oxides such as polyethylene oxide, polypropylene oxide or polybutylene oxide, styrene or their derivatives such as methylstyrene, indene, dicyclopentadiene, monomers, the amino or Imino groups such as dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminopropylmethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylammopropyl methacrylamide or allylamine, monomers which carry ammonium groups, such as, for example, in the present case as salts, such as those obtained by reacting the basic amino acid acid, sulfuric acid, acid, with acids, acid, such as sulfuric acid, acidic acid, acidic acid , or in quaternized form (examples of suitable quaternizing agents are dimethyl sulfate, diethyl sulfate, methyl chloride, ethyl chloride or benzyl chloride), such as dimethylami- noethyl acrylate hydrochloride, diallyldimethylammonium chloride, dimethylaminoethylacrylate methyl chloride, dimethylaminoethylaminopropyl methacrylamide methosulfate, vinylpyridinium salts or 1-vinylimidazolium salts; Monomers in which the amino groups and / or ammonium groups are only released after the polymerization and subsequent hydrolysis, such as, for example, N-vinylformamide or N-vinylacetamide and mixtures of the above-mentioned monomers.

For example, only one monomer of the general formula I can be polymerized to produce the polymers according to the invention. However, it is equally possible that a mixture or two or more monomers of the general formula I are polymerized. In addition, mixtures of a monomer of the general formula I or a mixture of two or more monomers of the general formula I can be polymerized with a further monomer or a mixture of two or more of the above-mentioned further monomers.

The polymers according to the invention can in principle be obtained by any form of polymerization. For example, it is possible, first of all, to polymerize by radical, anionic or cationic means only the olefinically unsaturated double bonds in the monomers of the general formula I, optionally in a mixture with one or more further monomers. The polymers obtainable in this way can be provided with appropriate selection of the monomers in varying amounts with radicals Z and, if appropriate, further functional groups which are important for the use of the polymer, for example acid groups or amino groups.

In the context of a preferred embodiment of the invention, the abovementioned monomers can, for example, first be subjected to a conventional free-radical polymerization which is triggered by a free-radical initiator. Care must be taken, however, that the temperature during the radical polymerization does not exceed the value at which homolytic bond cleavage takes place in the Z radical. However, it is equally possible that the polymerization is carried out in the presence of a radical initiator or in its absence at a temperature which is above the temperature required for homolytic bond cleavage in the Z radical. In this case, the residue Z acts as a radical initiator. Both the first stage (“core”) and the second stage (“shell”), or the synthesis of the highly branched polymer, can also be carried out by redox initiation (-OOH / Fe ^{+ π} ). The redox initiation of the first stage can be carried out by an additional initiator or by the monomer I itself.

In a particularly preferred embodiment, polymers according to the invention are produced by polymerizing only monomers of the general formula I at a temperature which is above the temperature for homolytic bond cleavage in the Z radical.

Polymers produced in this way are often referred to in the literature as highly branched polymers.

In a further embodiment of the present invention, the polymers according to the invention are carried out using monomers of the formula I in the presence of a radical initiator, but at a temperature above the temperature required for homolytic bond cleavage in the Z radical.

The polymers according to the invention can be produced in one step or in several steps. If polymerization is carried out in several stages, so-called core-shell polymers can be produced as polymers according to the invention.

For this purpose, a polymer core is first synthesized, the polymerization of which takes place with the participation of monomers of the general formula I. For this purpose, either polymers of the general formula I can be used individually or as a mixture of two or more with one another, but there can additionally be one of the above-mentioned further monomers or a mixture of two or more of these further monomers in the polymerization of the core polymer. The first stage of the polymerization can be initiated, for example, anionically, cationically or radically. The polymerization temperature in this first stage can be, for example, below the temperature required for the homolytic bond cleavage in the Z radical. After carrying out this first stage, a homopolymer or copolymer is obtained (depending on the monomer components used) which still has Z radicals.

In a second stage, further monomer can then be added and, without the addition of initiator, heated to a temperature which is above the value required for the homolytic bond cleavage in the Z radical. This initiates a grafting reaction in which further monomer is grafted onto the polymer core already produced in the first step.

In this two-stage reaction procedure, however, it is also possible to work in the first stage at a temperature which is above the temperature required for the homolytic bond cleavage in the Z radical. If this is the case, the polymerization temperature and the polymerization time should, however, be adjusted in such a way that, after the polymerization has ended, there are sufficient unsplit radical Z in the core polymer to enable further grafting of monomeric constituents.

A suitable value for the polymerization time is, for example, about 1 to 10 half-lives for the decomposition of the radical Z. Suitable methods for determining such half-lives are known to the person skilled in the art.

The polymers according to the invention which can be obtained in this way have a core-shell structure. Depending on the choice of monomers in the first stage and in the second stage, different core and shell properties can be achieved.

In the context of a further embodiment of the present invention, the polymerization can also be carried out in more than two steps, wherein in a third, fourth or fifth step, for example, further monomer with residues Z can be added in order to initiate further polymerization products. Conventional methods can be selected to terminate the polymerization in the different stages, for example termination by the addition of so-called radical scavengers, such as 1,4-benzoquinone.

The polymerization takes place under customary process conditions which can be used in free-radical polymerization. In the context of a preferred embodiment of the present invention, the polymerization is carried out in a liquid medium, for example in a solvent for the monomers involved or the polymer formed or in water.

In a preferred embodiment, the reaction mixture is freed of oxygen before the polymerization. This is done by conventional methods known to those skilled in the art.

The present invention therefore also relates to a process for the preparation of polymers, characterized in that at least one monomer of the general formula I

worin R¹ für einen Alkylenrest mit 1 bis 44 C-Atomen, Cycloalkylenrest mit 3 bis 44 C-Atomen, einen Arylenrest mit 4 bis 40 C-Atomen, einen Aralkylenrest mit 5 bis 40 C-Atomen oder einen Heteroarylrest mit 4 bis 40 C-Atomen, R , R und R jeweils unabhängig voneinander für H oder einen Alkylrest mit 1 bis 10 C- Atomen oder einen Arylrest mit 4 bis 12 C-Atomen und Z für einen Substituenten mit mindestens einer thermisch oder durch Redoxinitiatoren induziert homolytisch spaltbaren Bindung steht, wobei die homolytische Spaltung der Bindung in Z bei einer Temperatur von -10°C bis 150°C erfolgt, oder ein Gemisch aus zwei oder mehr solcher Monomeren, oder ein Gemisch aus einem Monomeren gemäß der allgemeinen Formel I und einem Monomeren, das nicht der allgemeinen Formel I entspricht oder ein Gemisch aus einem Monomeren gemäß der allgemeinen Formel I und einem Gemisch aus zwei oder mehr solcher Monomeren, die nicht der allgemeinen Formel I entsprechen, oder ein Gemisch aus zwei oder mehr Monomeren der allgemeinen Formel I und ein Gemisch aus zwei oder mehr Monomeren, die nicht der allgemeinen Formel I entsprechen, in einem Schritt oder in mehreren Schritten radikalisch polymerisiert werden.

wherein R ^{1 is} an alkylene radical with 1 to 44 C atoms, cycloalkylene radical with 3 to 44 C atoms, an arylene radical with 4 to 40 C atoms, an aralkylene radical with 5 to 40 C atoms or a heteroaryl radical with 4 to 40 C -Atoms, R, R and R each independently represent H or an alkyl radical having 1 to 10 C atoms or an aryl radical having 4 to 12 C atoms and Z represents a substituent with at least one thermally or redox initiator-induced homolytically cleavable bond , wherein the homolytic cleavage of the bond in Z takes place at a temperature of -10 ° C to 150 ° C, or a mixture of two or more such monomers, or a mixture of a monomer of the general formula I and a monomer which is not corresponds to the general formula I. or a mixture of a monomer of the general formula I and a mixture of two or more such monomers which do not correspond to the general formula I, or a mixture of two or more monomers of the general formula I and a mixture of two or more monomers, which do not correspond to the general formula I are polymerized by free radicals in one step or in several steps.

In a further embodiment of the process according to the invention, at least one of the polymerization steps is carried out in the presence of a free-radically polymerizable monomer which does not correspond to general formula I.

The polymers according to the invention can be used in a wide variety of applications. For example, these are additives, e.g. for lowering the viscosity, for improving processability, as a crosslinker, compatibilizer, blend component, for applications in "drug delivery", as a solubilizer and as an impact modifier.

The core-shell polymers according to the invention can be used in particular for modifying the impact resistance of plastics.

The present invention therefore also relates to the use of polymers according to the invention for the impact modification of plastics.

The invention is explained in more detail below by examples.

Examples

Example 1: Synthesis of 3-vinylphenylazomethylmalonodinitrile

1.19 g (10 mmol) methylmalononitrile are concentrated in 30 ml water and 5 ml. HCI dissolved and mixed with a little ice. The mixture is then diazotized at 0 ° C. with a well-cooled solution of 0.7 g (10 mmol) of NaNO ₂ in 20 ml of water. The resulting diazonium salt solution is then slowly added dropwise at 0 ° C. with the constant addition of ice to a solution of 10 g sodium acetate and 0.8 g (10 mmol) 3-aminostyrene in 25 ml water and 15 ml ethanol. After stirring for 30 minutes at room temperature, shake out 3 times with ether, dry the organic phase over Na ₂ SO ₄ and remove the solvent in vacuo. After purification by column chromatography (silica gel, hexane: ethyl acetate = 7: 3, V / N), 1.89 g (8.97 mmol, 90% yield) of the above compound are obtained as a yellow solid.

1H-ΝMR (300MHz, CDCI ₃ , 300K): δ in ppm = 7.89 (s, 1H, Hl); 7.72 (d, 1H, H3);

7.62 (d, 1H, H5); 7.49 (dd, 1H, H4); 6.78 (dd, 1H, H7); 5.88 (d, cis-H8); 5.40 (d,

1H, trans-H8); 2.18 (s, 3H, H10).

¹³ C-NMR (75 MHz, CDCI ₃ 300K): δ in ppm = 150.2 (C2); 139.1 (C6); 135.5

(C7); 131.4 (C4); 130.5 (C5); 121.2 (Cl); 122.8 (C3), 113.9 (C8); 63.9 (C9); 25.1 (C10).

Example 2: Synthesis of highly branched polystyrene

3-vinylphenylazomethylmalonodinitrile (I) and styrene are dissolved in toluene in the proportions given in table 1 while maintaining the total concentration given in table 1. The mixture is exposed to oxygen for 40 h polymerized at 80 ° C. The resulting polymer is precipitated in methanol and cleaned by falling over. Table 1 shows the approaches and results carried out.

Example 3: Preparation of a core polymer (core polymer 1)

320 mg sodium lauryl sulfate, 28 mg Na ₂ HPO and 25 mg Rongalit C ^® are dissolved in 25 ml water. A solution of 4 mg of FeSO ₄ -7H ₂ O and 3 mg of ethylenediaminetetraacetic acid disodium salt in 5 ml of water is then added. After adding 210 mg of 3-vinylphenylazomethylmalonodinitrile and 10.328 g of styrene, the mixture is freed from oxygen by freezing out three times, evacuating and then gassing with argon. To initiate the polymerization, 35 μl of an oxygen-free solution of 70% by weight of tert-butyl hydroperoxide in water are added. Polymerization takes place at 5 ° C. After 63 hours, the polymerization is stopped by adding 1,4-benzoquinone. For working up, the polymer is precipitated in 400 ml of methanol and then precipitated twice from methylene chloride in 300 ml of methanol. After drying, 2.17 g of copolymer are obtained (21% conversion).

Example 4: Preparation of a core polymer (core polymer 2) 3-vinylphenylazomethylmalonodinitrile and styrene are mixed with one another in the desired ratio and the mixture is freed from oxygen three times by freezing, evacuating and then gassing with argon and polymerized at 80 ° C. Depending on the 3-vinylphenylazomethylmalononitrile content and the desired functionality of the polymeric core, the polymerization is terminated after 1 to 10 half-lives by adding 1,4-benzoquinone. For processing tion, the polymer is precipitated in methanol and then precipitated twice from methylene chloride in methanol. After drying, the copolymer is obtained.

Example 5: Preparation of a core-shell polymer 188 mg of a core as described above (vinylphenylazomethylmalonodi- nitrile copolymer) are dissolved in 25 ml of toluene with 4 ml of N-vinylpyrrolidone. The mixture is freed from oxygen by freezing three times, evacuating and then gassing with argon. Then polymerized for 17 h at 85 ° C. The polymerization is terminated by adding 1,4-benzoquinone. The polymer is repeatedly precipitated in 300 ml of hexane / diethyl ether (1: 1, V: V). To demonstrate the chemical linkage between core and shell, the core-shell copolymer is extracted with water in order to remove any homopolyvinylpyrrolidone that may be present. After the extraction, the core-shell structure can be confirmed in 1H-NMR.

Claims

claims 1. polymer, obtainable by radical polymerization of at least one monomer of the general formula I.

wherein R ^{1 represents} an alkylene radical with 1 to 44 C atoms, a cycloalkylene radical with 3 to 44 C atoms, an arylene radical with 4 to 40 C atoms, an aralkylene radical with 5 to 40 C atoms or a heteroaryl radical with 4 to 40 C atoms, R ² , R ³ and R ⁴ each independently for H or an alkyl radical with 1 to 10 C atoms or an aryl radical with 4 to 12 C atoms and Z for a substituent with at least one thermally or through Redox initiators induce homolytically cleavable bond, the homolytic cleavage of the bond in Z taking place at a temperature of from -10 ° C. to 150 ° C. 2. Polymer according to claim 1, characterized in that R ^{4 represents} an arylene radical. 3. Polymer according to claim 1 or 2, characterized in that Z has a homolytically cleavable C-C or O-O bond. 4. Polymer according to one of claims 1 to 3, characterized in that Z has at least one nitrile radical. 5. Polymer according to one of claims 1 to 4, characterized in that Z is a radical of the general formula II - N = NR (II), wherein R ^{5 is} a linear or branched, saturated or unsaturated substituted alkyl radical having 2 to 10 carbon atoms or an optionally substituted aryl radical having 6 to 24 carbon atoms, a -CN group, a -COOR group or a -OC ( O) R group, where R is a linear or branched chain aliphatic, araliphatic or aromatic hydrocarbon group. Polymer according to one of claims 1 to 4, characterized in that Z represents a radical of the general formula III

stands. Process for the preparation of polymers, characterized in that at least one monomer of the general formula I

wherein R ^{1 is} an alkylene radical with 1 to 44 C atoms, cycloalkylene radical with 3 to 44 C atoms, an arylene radical with 4 to 40 C atoms, an aralkylene radical with 5 to 40 C atoms or a heteroaryl radical with 4 to 40 C atoms, R ² , R ³ and R ⁴ each independently of one another for H or an alkyl radical with 1 to 10 C atoms or an aryl radical with 4 to 12 C atoms and Z for a substituent with at least one thermally or is induced by redox initiators homolytically cleavable bond, the homolytic cleavage of the bond in Z takes place at a temperature of -10 to 150 ° C, or a mixture of two or more such monomers, or a mixture of a monomer according to general formula I and a monomer that does not correspond to general formula I. or a mixture of a monomer of the general formula I and a mixture of two or more such monomers which do not correspond to the general formula I, or a mixture of two or more monomers of the general formula I and a mixture of two or more monomers, which do not correspond to the general formula I are polymerized by free radicals in one step or in several steps. 8. The method according to claim 7, characterized in that the polymerization is carried out in several steps, the polymerization temperature in at least one of the steps being chosen such that a thermally induced homolytic cleavage of the bond in Z takes place. 9. The method according to any one of claims 7 or 8, characterized in that one of the polymerization steps is carried out in the presence of a free-radically polymerizable monomer which does not correspond to the general formula I. 10. The method according to any one of claims 7 to 9, characterized in that a first polymerization step is carried out at a temperature at which no homolytic cleavage takes place in the rest Z. 11. Use of polymers according to one of claims 1 to 6 or of polymers prepared according to one of claims 7 to 10 as additives, as crosslinkers, compatibilizers, blend components, for applications in "drug delivery", as solubilizers and impact modifiers.