CN104628897B - Styrene type poly chain transfer agent, its preparation method and the application in preparing process for preparing column type polymer brush thereof - Google Patents

Abstract

The invention discloses a styrene-type polychain transfer agent, its preparation method and its application in the preparation of columnar polymer brushes. The styrene-type polychain transfer agent is a polymer with the structure shown in formula (I), Among them, n is 10-20000, m is 1-20000, molecular weight distribution is 1.01-4.0, R is alkyl or phenyl; R' is alkyl, phenyl, alkoxy, alkylthio, phenoxy or phenylthio. The preparation method uses poly-p-vinylbenzyl ester with controllable molecular weight as a precursor, and prepares polystyrene main chain polychain transfer agent through hydrolysis, chlorination, substitution and other post-functionalization reactions. The polychain transfer agent used in the present invention has a degree of polymerization of up to 20000, and can be used to regulate and control multiple types of double bond-containing monomers to prepare columnar polymer brushes through R-terminal growth mode polymerization.

Description

Styrenic polychain transfer agent, its preparation method and its use in the preparation of columnar polymer brushes application in

technical field

The invention belongs to the field of polymer brush preparation, and in particular relates to a styrene-type polychain transfer agent, its preparation method and its application in synthesizing columnar polymer brushes.

Background technique

Columnar polymer brushes, as a unique class of one-dimensional nanostructures, have been increasingly studied due to their special topology and physicochemical properties. It has broad application prospects and significance in the fields of drug loading, as a template for preparing nanomaterials, and functional nanomaterials.

At present, the synthesis methods of polymer brushes mainly include living/controlled radical polymerization such as atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization (RAFT), nitroxide stabilized radical polymerization (NMP) and other methods. Among them, RAFT polymerization has the advantages of good tolerance of functional groups, various types of polymerizable monomers, and easy purification without metal catalysts. There are two ways to synthesize polymer brushes by RAFT polymerization: R-terminal method and Z-terminal method. The R-terminal chain transfer group is on the outside of the polymer brush, and the Z-terminal chain transfer group is on the inside of the polymer brush. Compared with the Z method, the advantage of the R-terminal synthesis is that the sidearm structure of the polymer brush is more stable and dense.

The key to the synthesis of polymer brushes by the RAFT method lies in the synthesis of the main chain of the polychain transfer agent. The polychain transfer agent with polystyrene as the main chain has a structure that is stable to acid and alkali and is not easy to degrade. The synthesis report of polychain transfer agent based on polystyrene main chain (J.Polym.Sci., Part A: Polym.Chem.2002,2956-2966 and Macromol.Rapid Commun.2014,35,234-241).

Contents of the invention

The object of the present invention is to provide a styrene-type polychain transfer agent, its preparation method and its application in synthesizing columnar polymer brushes. Synthetic columnar polymer brush.

A kind of styrene polychain transfer agent, is the polymer shown in formula (I) for structure:

In the formula (I), n is 10-20000, m is 1-20000, and the molecular weight distribution is 1.01-4.0;

R is one of substituted or unsubstituted alkyl, substituted or unsubstituted phenyl;

R' is substituted or unsubstituted alkyl, substituted or unsubstituted phenyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylthio, substituted or unsubstituted phenoxy, substituted or unsubstituted phenylthio;

The substituents on the alkyl, phenyl, alkoxy, alkylthio, phenoxy or phenylthio are independently selected from C ₁ -C ₅ alkyl, C ₁ -C ₅ alkoxy, C ₁ -C ₅ alkenyl or halogen.

In the present invention, the styrene-type polychain transfer agent represented by formula (I) is a random copolymer.

The degree of polymerization of the styrene-type polychain transfer agent of the present invention is controllable, and the R-terminal growth method can be used to synthesize a columnar polymer brush, and the obtained polymer brush uses polystyrene main chain as a skeleton, which is stable and non-degradable to acid and alkali; polymer The brush main chain length is controllable, up to 2000 and the molecular weight distribution is narrow.

Preferably, R is one of substituted or unsubstituted C ₁ -C ₁₈ alkyl, substituted or unsubstituted phenyl;

R' is substituted or unsubstituted C ₁ -C ₁₈ alkyl, substituted or unsubstituted phenyl, substituted or unsubstituted C ₁ -C ₁₈ alkoxy, substituted or unsubstituted C ₁ -C ₁₈ alkylthio group, substituted or unsubstituted phenoxy group, substituted or unsubstituted phenylthio group.

Preferably, the main chain structure is polystyrene, and the side chains contain chain transfer groups such as dithioester, trithioester, and xanthate.

The present invention also provides a kind of preparation method of described styrene polychain transfer agent, comprises the steps:

(1) Carrying out free radical polymerization or active/controllable free radical polymerization to vinyl benzyl ester to obtain poly-p-vinyl benzyl ester;

The structure of described p-vinylbenzyl ester is shown in formula (II):

In formula (II), R and n are as defined above, and the molecular weight distribution is 1.01 to 4.0;

(2) Under the action of alkali, the poly-p-vinylbenzyl ester obtained in step (1) undergoes a hydrolysis reaction to obtain poly-p-vinylbenzyl alcohol;

(3) Under the action of a chlorination reagent, the poly-p-vinylbenzyl alcohol obtained in step (2) undergoes a chlorination reaction to obtain poly-p-vinylbenzyl chloride;

(4) Substituting the poly-p-vinylbenzyl chloride obtained in step (3) with thiocarboxylate or thiocarbonate to obtain the styrene-type polychain transfer agent.

In step (1), the polymerization of vinyl benzyl ester comprises common free radical polymerization and RAFT polymerization, ATRP polymerization, NMP polymerization activity/controllable free radical polymerization under initiator, light or thermal action, the temperature of described polymerization reaction The temperature ranges from 30°C to 110°C, and the polymerization time ranges from 1 hour to 3 days.

As a preference, in step (1), the polymerization is carried out under the action of cumyl thiobenzoate and azobisisobutyronitrile.

In step (2) and step (3), side groups of chain transfer groups are introduced through reactions such as hydrolysis and substitution of the poly-p-vinylbenzyl ester precursor, and the degree of functionalization m/n is 0.1% to 100%.

As a preference, in step (4), the thiocarboxylate or thiocarbonate is sodium dodecyl trithiocarbonate, sodium dithiobenzoate or sodium ethyl xanthate.

The present invention also provides a preparation method of a columnar polymer brush, comprising:

Under the action of an initiator or heat, the styrene-type polychain transfer agent and the double-bond-containing monomer undergo RAFT polymerization reaction to obtain the columnar polymer brush.

Preferably, the double bond-containing monomer includes acrylic acid, acrylate ester, acrylamide, methacrylic acid, methacrylate ester, methacrylamide, vinyl acetate, styrene and derivatives thereof.

Preferably, the temperature of the RAFT polymerization reaction is 30° C. to 110° C., and the polymerization reaction time is 1 hour to 3 days.

The invention also provides a columnar polymer brush prepared by the preparation method.

Compared with the prior art, the beneficial effects of the present invention are: (1) For the first time, the length-controllable and narrow-distribution styrene main chain polychain transfer agent is prepared; while the prior art can only prepare polychain transfer agents with a main chain polymerization degree less than 150 agent, causing the final synthesized columnar polymer brushes to lose their columnar characteristics to some extent. (2) The polychain transfer agent used in the present invention has the following characteristics: (i) the polystyrene main chain is stable and non-degradable to acid and alkali as the polymer brush skeleton structure; (ii) the length of the polymer brush main chain is controllable, the highest It can reach 2000; (iii) polymer brushes with narrow molecular weight distribution (≤1.4) can be prepared; (iv) homopolymerization or copolymerization of many different types of double bond monomers can be regulated according to different R groups and X atoms.

Description of drawings

Fig. 1 is the proton nuclear magnetic resonance spectrogram of the product that embodiment 4 obtains.

detailed description

The present invention will be further described below in conjunction with specific examples.

The obtained polymer and the columnar polymer brushes were determined by GPC. The number average molecular weight and molecular weight distribution of the polymer were measured in gel permeation chromatography (Waters 1515 Isocratic high performance liquid chromatography pump), THF was used as the mobile phase, 40° C., and the flow rate was 1.0 mL/min.

Embodiment 1 The synthesis of p-vinylbenzyl polyacetate

Add 3.0g (17.0mmol) p-vinylbenzyl acetate, 3mg (0.011mmol) cumyl thiobenzoate and 0.1mg azobisisobutyronitrile into the reaction bottle, seal it and place it in a 60°C oil bath for reaction After 12 hours of reaction, the mixture was poured into 100 mL of methanol solution to precipitate, filtered, and the obtained polymer was vacuum-dried to obtain the product with a yield of 60%. The obtained polymer had a number average molecular weight of 80,000 and a molecular weight distribution of 1.2.

The synthesis of embodiment 2 polyvinyl benzyl alcohol

Add 1.3g of p-vinylbenzyl acetate (8.5mmol ester group) and 0.3g of sodium hydroxide (8.5mmol) obtained in Example 1 to the reaction flask, dissolve in tetrahydrofuran and react at room temperature for 12h, and pour the mixture into Precipitate in diethyl ether, filter, and vacuum-dry the obtained polymer to obtain the product with a yield of 92%. The obtained polymer had a number average molecular weight of 70,000 and a molecular weight distribution of 1.2.

The synthesis of embodiment 3 polyvinyl benzyl chloride

Add 1.1 g of polyvinylbenzyl alcohol (8.5 mmol hydroxyl) obtained in Example 2 to the reaction flask, dissolve it in 20 mL of tetrahydrofuran, add 5 mL of thionyl chloride to react at room temperature for 12 hours, and pour the mixture into 200 mL of ether for precipitation, Filtration and vacuum drying of the resulting polymer yielded the product with a yield of 85%. The obtained polymer had a number average molecular weight of 70,000 and a molecular weight distribution of 1.2.

Example 4 Synthesis of polychain transfer agent whose side group is trithioester

Add 0.65g of poly-p-vinylbenzyl chloride (4.3mmol halogen atom) obtained in Example 3 to the reaction flask, dissolve it in 20mL of tetrahydrofuran, add 0.14g of sodium dodecyltrithiocarbonate (4.6mmol) and react at room temperature for 12h, After the reaction, the mixture was poured into 200 mL of ether to precipitate, filtered, and the obtained polymer was vacuum-dried to obtain the product with a yield of 73%. The obtained polymer had a number average molecular weight of 130,000 and a molecular weight distribution of 1.3. The proton magnetic spectrum (CDCl ₃ ) of the product is shown in FIG. 1 . Each signal peak in Fig. 1 can be assigned according to formula (3), proves to successfully obtain the polychain transfer agent of trithioester side group.

Embodiment 5 side group is the polychain transfer agent synthesis of dithioester

Other reaction conditions were the same as in Example 4, except that sodium dodecyl trithiocarbonate was replaced by sodium dithiobenzoate, and the final polymer yield was 70%. The obtained polymer had a number average molecular weight of 130,000 and a molecular weight distribution of 1.3.

Example 6 Synthesis of polychain transfer agent whose side group is xanthate

Other reaction conditions were the same as in Example 4, except that sodium dodecyl trithiocarbonate was replaced by sodium ethyl xanthate, and the final polymer yield was 80%. The obtained polymer had a number average molecular weight of 130,000 and a molecular weight distribution of 1.3.

Example 7 Synthesis of columnar polymer brushes with polymethylacrylate side chains

In the reaction bottle, add the polychain transfer agent (0.05mmol chain transfer agent group), 0.4g methyl acrylate (5mmol) and 2mg azobisisobutyronitrile that the side group that 18.9mg embodiment 4 obtains is trithioester, After dissolving in 4 mL of anisole, react at 60°C for 5 hours, then pour the mixture into 100 mL of ether to precipitate, filter, and vacuum-dry the obtained polymer to obtain the product with a yield of 40%. The obtained polymer had a number average molecular weight of 600,000 and a molecular weight distribution of 1.3.

Example 8 Synthesis of a columnar polymer brush with polyisopropylacrylamide as its side chain

Other polymerization conditions were the same as in Example 7, except that the monomer was replaced by 0.5g isopropylacrylamide (5mmol), reacted in an oil bath at 60°C for 6h, poured into 100mL ether for precipitation, and filtered the obtained polymer in a vacuum After drying, the yield was 35%. The obtained polymer had a number average molecular weight of 560,000 and a molecular weight distribution of 1.3.

Example 9 Synthesis of columnar polymer brushes with polyacrylic acid side chains

Other polymerization conditions were the same as in Example 7, except that the monomer was replaced by 0.36 g of acrylic acid (5 mmol), reacted in an oil bath at 60° C. for 6 h, poured into 100 mL of ether to precipitate, filtered the obtained polymer, dried in vacuo, and collected The rate is 40%.

Example 10 Synthesis of columnar polymer brushes whose side chains are polymethyl methacrylate

Other polymerization conditions were the same as in Example 7, except that the monomer was replaced by 0.4g methyl methacrylate (5mmol), reacted in an oil bath at 60°C for 5h, poured into 100mL ether for precipitation, and filtered the resulting polymer in a vacuum After drying, the yield was 40%. The obtained polymer had a number average molecular weight of 670,000 and a molecular weight distribution of 1.3.

Example 11 Synthesis of columnar polymer brushes with polymethylisopropylacrylamide side chains

Other polymerization conditions were the same as in Example 7, except that the monomer was replaced by 0.5 g methyl isopropyl acrylamide (5 mmol), reacted in an oil bath at 60°C for 6 hours, poured into 100 mL of ether to precipitate, and filtered the obtained polymerization After vacuum drying, the yield was 35%. The obtained polymer had a number average molecular weight of 560,000 and a molecular weight distribution of 1.3.

Example 12 Synthesis of columnar polymer brushes with polymethacrylic acid as the side chain

Other polymerization conditions were the same as in Example 7, except that the monomer was replaced by 0.36g methacrylic acid (5mmol), reacted in an oil bath at 60°C for 6h, poured into 100mL ether for precipitation, and filtered the obtained polymer after vacuum drying , the yield was 43%.

Example 13 Synthesis of columnar polymer brushes with polystyrene side chains

Other polymerization conditions are the same as Example 7, except that the monomer is replaced by 0.5g styrene (5mmol), and the polychain transfer agent is replaced by the polychain transfer agent ( 0.05 mmol chain transfer agent groups). After reacting in an oil bath at 60° C. for 12 h, it was poured into 100 mL of methanol for precipitation, and the obtained polymer was filtered and vacuum-dried, and the yield was 25%. The obtained polymer had a number average molecular weight of 500,000 and a molecular weight distribution of 1.3.

Example 14 Synthesis of columnar polymer brushes whose side chains are polyvinyl acetate

Other polymerization conditions are the same as in Example 7, except that the monomer is replaced by 0.4g vinyl acetate (5mmol), and the polychain transfer agent is replaced by 18.4mg. The side group obtained in Example 6 is the polychain transfer of xanthate agent (0.05mmol chain transfer agent group). After reacting in an oil bath at 60° C. for 5 h, it was poured into 100 mL of n-hexane for precipitation, and the obtained polymer was filtered and vacuum-dried, and the yield was 35%. The obtained polymer had a number average molecular weight of 680,000 and a molecular weight distribution of 1.3.

Example 15 Synthesis of columnar polymer brushes whose side chains are copolymers of methyl acrylate and isopropylacrylamide

Other polymerization conditions were the same as in Example 7, except that 0.5 g of isopropylacrylamide (5 mmol) was added simultaneously as a comonomer. After reacting in an oil bath at 60° C. for 5 h, it was poured into 100 mL of n-hexane for precipitation, and the obtained polymer was filtered and vacuum-dried, and the yield was 35%. The obtained polymer had a number average molecular weight of 900,000 and a molecular weight distribution of 1.3.

Example 16 Synthesis of Columnar Polymer Brushes with Side Chains of Polymethylacrylate and Polyisopropylacrylamide Block Copolymer

Other polymerization conditions were the same as in Example 8, except that the polychain transfer agent was replaced by 0.16 g of columnar polymer brushes (0.05 mmol of chain transfer agent groups) in Example 7 whose side chains were polymethyl acrylate. After reacting in an oil bath at 60° C. for 7 h, it was poured into 100 mL of ether for precipitation, and the obtained polymer was filtered and vacuum-dried, and the yield was 55%. The obtained polymer had a number average molecular weight of 1.04 million and a molecular weight distribution of 1.3.

Claims (9)

1. a styrene type polychain transfer agent, is characterized in that, is the polymer shown in formula (I) for structure: In the formula (I), n is 10-20000, m is 1-20000, and the molecular weight distribution is 1.01-4.0; R is one of substituted or unsubstituted alkyl, substituted or unsubstituted phenyl; R' is substituted or unsubstituted alkyl, substituted or unsubstituted phenyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylthio, substituted or unsubstituted phenoxy, substituted or unsubstituted phenylthio; The substituents on the alkyl, phenyl, alkoxy, alkylthio, phenoxy or phenylthio are independently selected from C ₁ -C ₅ alkyl, C ₁ -C ₅ alkoxy, C ₁ -C ₅ alkenyl or halogen. 2. The styrene-type polychain transfer agent according to claim 1, wherein R is one of substituted or unsubstituted C ₁ -C ₁₈ alkyl, substituted or unsubstituted phenyl; R' is substituted or unsubstituted C ₁ -C ₁₈ alkyl, substituted or unsubstituted phenyl, substituted or unsubstituted C ₁ -C ₁₈ alkoxy, substituted or unsubstituted C ₁ -C ₁₈ alkylthio group, substituted or unsubstituted phenoxy group, substituted or unsubstituted phenylthio group. 3. a preparation method of styrene type polychain transfer agent as claimed in claim 1 or 2, is characterized in that, comprises the steps: (1) Carrying out free radical polymerization or active/controllable free radical polymerization to vinyl benzyl ester to obtain poly-p-vinyl benzyl ester; The structure of described poly-p-vinylbenzyl ester is shown in formula (II): In formula (II), the definitions of R and n are the same as those in claim 1 or 2, and the molecular weight distribution is 1.01 to 4.0; (2) under the action of alkali, the poly-p-vinylbenzyl ester obtained in step (1) undergoes a hydrolysis reaction Obtain polyvinyl benzyl alcohol; (3) Under the action of a chlorination reagent, the poly-p-vinylbenzyl alcohol obtained in step (2) undergoes a chlorination reaction to obtain poly-p-vinylbenzyl chloride; (4) Substituting the poly-p-vinylbenzyl chloride obtained in step (3) with thiocarboxylate or thiocarbonate to obtain the styrene-type polychain transfer agent. 4. The preparation method of the styrene-type polychain transfer agent according to claim 3, characterized in that, in step (1), the polymerization temperature is 30° C. to 110° C., and the polymerization time is 1 hour to 3 days. 5. the preparation method of styrene polychain transfer agent according to claim 3 is characterized in that, in step (4), described thiocarboxylate or thiocarbonate are alkyl trithio Carbonates, Dithiobenzoates or Alkyl Xanthates. 6. A method for preparing a columnar polymer brush, comprising: Under the action of an initiator or heat, the styrene-type polychain transfer agent described in claim 1 or 2 regulates the RAFT polymerization reaction of the double bond-containing monomer to obtain the columnar polymer brush. 7. the preparation method of columnar polymer brush according to claim 6 is characterized in that, described monomer containing double bond comprises acrylic acid, acrylate, acrylamide, methacrylic acid, methacrylate, methacrylic acid Amides, vinyl acetate, styrene and its derivatives. 8 . The method for preparing a columnar polymer brush according to claim 6 , wherein the temperature of the RAFT polymerization reaction is 30° C. to 110° C., and the polymerization reaction time is 1 hour to 3 days. 9. A columnar polymer brush, characterized in that it is prepared by the preparation method described in any one of claims 6-8.