CN100418992C - Preparation method of a hydrophilic-hydrophobic graft polymer with controllable main and side chain lengths - Google Patents

Abstract

The invention discloses a method for preparing a hydrophilic-hydrophobic graft polymer with controllable main and side chain lengths, belonging to the technical field of graft polymer preparation. The present invention synthesizes polystyrene (PSt) and polyacrylate hydrophobic macromolecular chains with relative molecular mass distribution ≤ 1.2 by atom transfer radical polymerization; obtains relative molecular mass through hydrolysis reaction under acidic conditions Controllable and narrowly distributed polymethacrylic acid or polyacrylic acid hydrophilic macromolecular chain; use the halogen atom at the end of the hydrophobic macromolecular chain to carry out nucleophilic substitution reaction with the carboxyl group on the side group of the hydrophilic macromolecular chain in solution , The hydrophobic chain is "assembled" on the hydrophilic chain to form a hydrophilic-hydrophobic graft polymer; the length of the macromolecular chain can be controlled by adjusting the ratio of the initiator to the monomer. Hydrophilic-hydrophobic graft polymers with controllable main and side chain lengths can be prepared by selecting hydrophilic chains with different lengths as the main chain and hydrophobic chains with different lengths for "assembly".

Description

Preparation method of a hydrophilic-hydrophobic graft polymer with controllable main and side chain lengths

technical field

The invention discloses a method for preparing a hydrophilic-hydrophobic graft polymer with controllable main and side chain lengths, belonging to the technical field of graft polymer preparation. Hydrophobic macromolecular chains with controllable molecular chain length and halogen atoms at the end were synthesized by atom transfer radical polymerization, and polymethacrylate was prepared by hydrolyzing poly-tert-butyl methacrylate (or poly-tert-butyl acrylate) under acidic conditions. Acrylic acid (or polyacrylic acid), change the ratio of monomer and initiator in the atom transfer radical polymerization to control the length of the hydrophobic macromolecular chain, select the hydrolysis of the above-mentioned hydrophobic macromolecular chain of different lengths to obtain polymers with different lengths Methacrylic acid (or polyacrylic acid) hydrophilic macromolecular chain; the grafting was successfully "assembled" through the nucleophilic substitution reaction between the halogen atom at the end of the hydrophobic macromolecular chain and the carboxyl group of the side group of the hydrophilic macromolecular chain polymer. This hydrophilic-hydrophobic polymer can be further self-assembled in a selective solvent to form a regular core-shell structure microsphere, changing the ratio and length of the hydrophobic chain to the hydrophilic chain, and changing the size of the microsphere and the carboxyl group on the surface. content purpose.

Background technique

Grafted polymers can self-assemble in specific solvents to form stable particles, and have broad application prospects in drug delivery and release, and functionalized materials. Grafted polymers can be prepared by a variety of methods, but sometimes it is difficult to obtain a regular polymer through a simple polymerization reaction, and the required small molecules or macromolecules are introduced into the polymer chain through the interaction between the polymer chain and the molecule. The method of structure has gradually been researched and applied. Atom Transfer Radical Polymerization (ATRP) is a polymerization method that has emerged in recent years. Through the ATRP method, polymers with controllable molecular weight and narrow molecular weight distribution can be obtained. It is an ideal method for preparing polymers containing specific groups. Selection, such as obtaining a molecular chain with a halogen atom (chlorine or bromine atom) at the end. The present invention uses the halogen atom at the end of the hydrophobic macromolecular chain to carry out nucleophilic substitution with the side group carboxyl group of polymethacrylic acid (or polyacrylic acid) obtained by hydrolysis, so as to realize the "assembly" of the hydrophobic macromolecular chain into the hydrophilic The purpose on the main chain is to prepare a hydrophilic-hydrophobic graft polymer with hydrophilic polymethacrylic acid or polyacrylic acid as the backbone and hydrophobic macromolecular chains as side branches.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a hydrophilic-hydrophobic graft polymer with controllable main and side chain lengths, and synthesize hydrophobic macromolecular chains with controllable molecular weights respectively by atom transfer radical polymerization; Since the pendant tert-butyl group of tert-butyl methacrylate or tert-butyl acrylate is easily hydrolyzed into a carboxyl group, the length-controllable hydrophilicity can be obtained by hydrolyzing poly-tert-butyl methacrylate or tert-butyl acrylate under acidic conditions The macromolecular chain polymethacrylic acid or polyacrylic acid is continuously subjected to nucleophilic substitution reaction to prepare a hydrophilic-hydrophobic graft polymer with controllable main chain and side chain length.

Technical scheme of the present invention:

Synthesis of polystyrene PSt or polyacrylates (polymethyl methacrylate PMMA, poly tert-butyl methacrylate PtBMA, poly tert-butyl acrylate PtBA, poly-n-butyl methacrylate PnBMA) by atom transfer radical polymerization , poly(n-butyl acrylate, PnBA, etc.) hydrophobic macromolecular chain; by hydrolyzing PtBMA or PtBA under acidic conditions, polymethacrylic acid PMAA or polyacrylic acid PAA hydrophilic macromolecular chain; The halogen atom at the end of the molecular chain undergoes a nucleophilic substitution reaction with the carboxyl group on the side group of the hydrophilic macromolecular chain to form a hydrophilic-hydrophobic graft polymer. The general formula is:

COOCH₃，COOC(CH₃)₃，COO(CH₂)₃CH₃。R²为H，CH₃。In the formula, 20≤n≤200, 20≤m≤200, p represents the degree of substitution, and the range of p is 5%-20%. R is H, CH ₃ , R ¹ is

COOCH ₃ , COOC(CH ₃ ) ₃ , COO(CH ₂ ) ₃ CH ₃ . ^R2 is H, _CH3 .

The preparation of hydrophobic macromolecular chain, its reaction formula is as follows:

In the formula, X is Cl or Br.

The atom transfer radical polymerization method is to use a halogen-containing compound (in theory, an alkyl halide or an aromatic sulfonyl chloride containing an inductive conjugated group at the α position can be used as an ATRP initiator), and the transition metal and the coordination compound are formed In the coordination system, the rapid balance of dormant species and active species can be achieved, so that the monomer can be polymerized. It can complete the reaction under milder conditions, and the polymerization reaction is stable, and a polymer with a relatively narrow molecular mass distribution can be obtained. The relative molecular mass of the polymer in the ATRP reaction depends directly on the molar ratio of monomer to initiator.

The preparation method of the hydrophobic macromolecular chain is to use the hydrophobic monomer as the polymerization monomer, select the initiator with a specific structure, and carry out the atom transfer radical polymerization reaction in the presence of the complexing agent and the catalyst to prepare the hydrophobic macromolecules Chain, changing the molar ratio of monomer and initiator to control the relative molecular mass of the macromolecular chain.

The specific preparation process is: use hydrophobic monomers as polymerization monomers, select haloalkanes or aromatic sulfonyl chlorides containing inductive conjugated groups at the α position as initiators, and carry out atom transfer free radicals in the presence of complexing agents and catalysts Polymerization reaction to obtain polystyrene or polyacrylate hydrophobic macromolecular chains containing halogen atoms at the end, the molar ratio of polymerized monomer: complexing agent: catalyst: initiator is determined as n: 1: 2: 1, Change the molar ratio of the monomer to the initiator to 20≤n≤200 to control the relative molecular mass of the macromolecular chain, control the reaction temperature at 80-130°C, control the reaction time at 6-12 hours, and the complexing agent is tetramethylbenzene Diamine, pentamethyldiethylenetriamine or bipyridine, the catalyst is cuprous chloride, cuprous bromide or ferrous chloride, and the initiator is methyl α-bromopropionate or α- Ethyl bromopropionate.

The preparation method of the hydrophilic macromolecular chain PMAA includes: hydrolyzing PtBMA as a raw material, selecting 1,4-dioxane as a solvent to dissolve the PtBMA, and adding a certain amount of concentrated hydrochloric acid for reflux. The temperature of the hydrolysis reaction is controlled at 75-95°C, and the reaction time is controlled at 12-40 hours. After the reaction is completed, cyclohexane or n-hexane is added dropwise to precipitate and filtered with suction to obtain the hydrolyzate, concentrated hydrochloric acid and 1,4-dioxine The volume ratio of the hexacyclic rings is 1:10-1:20.

The preparation method of the hydrophilic macromolecular chain PAA is as follows: PtBA is used as a raw material for hydrolysis, dimethyl sulfoxide is selected as a solvent to dissolve the PtBA, and a certain amount of concentrated hydrochloric acid is added for reflux. The hydrolysis reaction temperature is controlled at 85-95°C, and the reaction time is controlled at 20-40 hours. After the reaction is completed, petroleum ether or n-hexane is added dropwise to precipitate and filter with suction to obtain the hydrolyzate. The volume ratio of concentrated hydrochloric acid to dimethyl sulfoxide 1:10 to 1:20.

Synthesis of hydrophilic-hydrophobic graft polymer: Add PMAA or PAA, a certain amount of hydrophobic macromolecular chains to the reaction vessel in sequence, use N,N-dimethylformamide as solvent, stir well, add hydrophobic Triethylamine in an amount of 1-5 times the number of moles of the macromolecular chain, the reaction temperature is controlled at 30-50°C, and the reaction time is controlled at 6-20 hours. After the reaction is completed, it is cooled naturally, left to stand, and the oily substance in the lower layer is collected, and then used A certain amount of chloroform or tetrahydrofuran is repeatedly washed to remove unreacted macromolecules to obtain a hydrophilic-hydrophobic graft polymer. Its reaction formula is as follows:

R²＝CH₃时，所述亲水-疏水性接枝聚合物为聚甲基丙烯酸-g-聚苯乙烯接枝聚合物。where R is H and ^R1 is

When R ² =CH ₃ , the hydrophilic-hydrophobic graft polymer is polymethacrylic acid-g-polystyrene graft polymer.

Where R is H, R ¹ is COOC(CH ₃ ) ₃ , and R ² =CH ₃ , the hydrophilic-hydrophobic graft polymer is polymethacrylic acid-g-polyacrylate tert-butyl ester graft polymer .

Where R is CH ₃ , R ¹ is COOC(CH ₃ ) ₃ , and R ² =CH ₃ , the hydrophilic-hydrophobic graft polymer is polymethacrylic acid-g-polymethacrylate tert-butyl ester branch polymer.

Where R is CH ₃ , R ¹ is COOCH ₃ , and R ² =CH ₃ , the hydrophilic-hydrophobic graft polymer is polymethacrylic acid-g-polymethylmethacrylate graft polymer.

Where R is CH ₃ , R ¹ is COO(CH ₂ ) ₃ CH ₃ , and R ² =CH ₃ , the hydrophilic-hydrophobic graft polymer is polymethacrylic acid-g-polymethacrylic acid n-butyl Ester graft polymers.

R²＝H时，所述亲水-疏水性接枝聚合物为聚丙烯酸-g-聚苯乙烯接枝聚合物。where R is H and ^R1 is

When R ² =H, the hydrophilic-hydrophobic graft polymer is polyacrylic acid-g-polystyrene graft polymer.

Wherein R is H, R ¹ is COOC(CH ₃ ) ₃ , and R ² =H, the hydrophilic-hydrophobic graft polymer is polyacrylic acid-g-polyacrylate tert-butyl ester graft polymer.

Wherein R is CH ₃ , R ¹ is COOC(CH ₃ ) ₃ , and R ² =H, the hydrophilic-hydrophobic graft polymer is polyacrylic acid-g-poly tert-butyl methacrylate graft polymer .

Where R is CH ₃ , R ¹ is COOCH ₃ , and R ² =H, the hydrophilic-hydrophobic graft polymer is polyacrylic acid-g-polymethyl methacrylate graft polymer.

Where R is CH ₃ , R ¹ is COO(CH ₂ ) ₃ CH ₃ , and R ² =H, the hydrophilic-hydrophobic graft polymer is polyacrylic acid-g-poly-n-butyl methacrylate grafted polymer.

In the above-mentioned nucleophilic substitution reaction, select PMAA or PAA with different lengths as the main chain and hydrophobic chains with different lengths as the side chains to obtain hydrophilic-hydrophobic graft polymers with different lengths of the main chain and side chains.

After characterization, the molecular weight of various macromolecular chains is controllable, and the relative molecular mass distribution is uniform (M _w /M _n <1.20). The relative molecular mass of various macromolecular chains can be controlled by changing the molar ratio of monomer and initiator. All kinds of hydrophilic-hydrophobic grafted polymers have clear structures, and the degree of grafting tends to be saturated.

Beneficial effects of the present invention: the present invention provides a method for preparing a hydrophilic-hydrophobic graft polymer whose main chain and side chain length can be controlled. Hydrophobic polyacrylate or polystyrene macromolecular chains with a relative molecular mass distribution of ≤1.2 were synthesized by atom transfer radical polymerization; the relative molecular mass of various macromolecular chains can be adjusted by adjusting the ratio of initiator to monomer To control, that is to say, to control the length of the molecular chain. Further, polyacrylate macromolecular chains are hydrolyzed under acidic conditions to produce PMAA or PAA with a narrow relative molecular mass distribution. In the solution, the halogen atom at the end of the hydrophobic macromolecular chain and the carboxyl group on the side group of the hydrophilic chain are used for nucleophilic substitution reaction, and the hydrophobic chain is "assembled" on the hydrophilic chain to form a graft polymer, which can realize Preliminary controllability of branch number.

Detailed ways

Embodiment 1, the synthesis of hydrophobic macromolecular chain PtBMA

At room temperature, add pentamethyldiethylenetriamine, CuCl, ethyl α-bromopropionate, and monomers in sequence according to the proportions in the container (according to the relative molecular mass, n is required to be 50). Stir to make it fully mixed, after 1-5 cycles of freezing and thawing, continuously inject high-purity nitrogen for 20-60 minutes and then seal it. React in an oil bath at 100°C for 6 hours, take it out, cool naturally, dissolve the reaction product with tetrahydrofuran, pass the solution through a metal oxide glass column to remove residual CuCl, add dropwise methanol/water (methanol/water volume ratio is 1: 1-1:5) in the mixed medium, filtered, repeated operations, and vacuum-dried to constant weight to obtain PtBMA.

Embodiment 2, the synthesis of hydrophobic macromolecular chain PSt

Add bipyridine, CuBr, methyl α-bromopropionate, and monomers sequentially in the reaction vessel according to the ratio at room temperature (n is required to be 200 according to the relative molecular mass). Stir to make it fully mixed, after several cycles of freezing and thawing, continue to pass high-purity nitrogen gas for 45 minutes and then seal it. React in an oil bath at 130°C for 10 hours, take it out, cool naturally, dissolve the reaction product with cyclohexane, mix and wash the solution with alumina powder, filter to remove residual CuBr, drop into ethanol medium to precipitate, filter, repeat The operation was performed three times, and vacuum-dried to constant weight, PSt was obtained.

Embodiment 3, the synthesis of hydrophobic macromolecular chain PMMA

At room temperature, tetramethylethylenediamine, FeCl ₂ , methyl α-bromopropionate, and monomers are sequentially added in proportion to the container (according to the relative molecular mass, n is required to be 100). Stir to make it fully mixed, after several cycles of freezing and thawing, continue to pass high-purity nitrogen gas for 60 minutes and then seal it. React in an oil bath at 80°C for 8 hours, take it out, cool naturally, dissolve the reaction product with N,N-dimethylformamide, pass the solution through an alumina glass column to remove residual FeCl ₂ , add dropwise into ethanol/water ( Ethanol/water volume ratio is 1: 3-1: 5) in the mixed medium of precipitation, filter, repeat operation three times, vacuum dry to constant weight, obtain PMMA.

Embodiment 4, the synthesis of hydrophobic macromolecular chain PtBA

At room temperature, tetramethylethylenediamine, CuCl, ethyl α-bromopropionate, and monomers are sequentially added in proportion to the flask (according to the relative molecular mass, n is required to be 20). Stir to make it fully mixed, after freezing and thawing cycles, continue to pass high-purity nitrogen gas for 60 minutes and then seal it. React in an oil bath at 100°C for 12 hours, cool naturally after the end, dissolve the reaction product with tetrahydrofuran, mix and wash the solution with alumina powder, filter, remove residual CuCl, add methanol/water dropwise (methanol/water volume ratio is 1:1-1:5) in the mixed medium, filtered, repeated three times, and vacuum-dried to constant weight to obtain PtBA.

Embodiment 5, the synthesis of hydrophobic macromolecular chain PnBA

At room temperature, add pentamethyldiethylenetriamine, CuBr, methyl α-bromopropionate, and monomers (n is 75 according to the relative molecular mass) in the flask in sequence. Stir well, go through freezing and thawing cycles, and keep feeding high-purity nitrogen for 60 minutes before sealing. React in an oil bath at 90°C for 9 hours, cool naturally after the end, dissolve the reaction product with dimethyl sulfoxide, wash the solution with alumina powder, remove residual metal components, add methanol/water (methanol/water volume ratio 1:1-1:5) in the mixed medium, filtered, repeated three times, and vacuum-dried to constant weight to obtain PnBA.

Embodiment 6, the synthesis of hydrophobic macromolecular chain PnBMA

Add bipyridine, CuCl, ethyl α-bromopropionate, and monomers in the flask in sequence at room temperature (according to the relative molecular mass, n is required to be 125). Stir well, go through freezing and thawing cycles, and keep feeding high-purity nitrogen for 60 minutes before sealing. React in an oil bath at 85°C for 9 hours, cool naturally after the end, dissolve the reaction product with DMSO, wash with alumina powder, remove residual metal components, add methanol/water dropwise (methanol/water volume ratio is 1:1- 1:5) in a mixed medium, filtered, repeated three times, and vacuum-dried to constant weight to obtain PnBMA.

Embodiment 7, the synthesis of hydrophilic macromolecular chain

Add 1g of PtBMA to the flask, dissolve it with 30mL of 1,4-dioxane, then add 1.5-3mL of concentrated hydrochloric acid, reflux reaction in an oil bath at 75-95°C for 12-40 hours, take out the sample after the end, drop Add cyclohexane or n-hexane to make it precipitate, filter it with suction, and dry it in vacuum to constant weight to obtain the hydrolyzate.

Embodiment 8, the synthesis of hydrophilic macromolecular chain

Add 1g of PtBA to the flask, dissolve it with 30mL dimethyl sulfoxide, then add 1.5-3mL concentrated hydrochloric acid, reflux reaction in an oil bath at 85-95°C for 20-40 hours, take out the sample after the end, add petroleum ether or Precipitate with n-hexane, filter with suction, and dry in vacuum until constant weight to obtain the hydrolyzate.

Embodiment 9, the preparation of hydrophilic-hydrophobic graft polymer

Add PMAA or PAA obtained by hydrolysis according to Example 7 or Example 8, a predetermined amount of hydrophobic macromolecular chains, DMF 5-20mL, stir and dissolve in the container, add 1-5mL of triethylamine, and heat up to 30-50 ℃ for 6 to 20 hours, cooled, let stand, and collected the lower layer of oil. Repeated washing with a certain amount of chloroform or tetrahydrofuran to remove unreacted macromolecules to obtain a hydrophilic-hydrophobic graft polymer.

Claims (7)

1. the preparation method of the controlled hydrophilic-hydrophobic graft polymer of a master, side chain length is characterized in that being contained by the synthetic end of Transfer Radical Polymerization the polystyrene PSt or the polyacrylate(s) hydrophobicity macromolecular chain of halogen atom; By making polymethyl tert-butyl acrylate PtBMA or polyacrylic acid tert-butyl ester PtBA hydrolysis under acidic conditions, obtain polymethyl acrylic acid PMAA or polyacrylic acid PAA wetting ability macromolecular chain; Utilize the halogen atom of hydrophobicity macromolecular chain end and the carboxyl on the wetting ability macromolecular chain side group to carry out nucleophilic substitution reaction in solution, form hydrophilic-hydrophobic graft polymer, its general formula is:

In the formula, 20≤n≤200,20≤m≤200, p represents the replacement degree, and the scope of p is 5%-20%, and R is H or CH ₃, R ¹For

COOCH ₃, COOC (CH ₃) ₃Or COO (CH ₂) ₃CH ₃, R ²Be H or CH ₃

Described polyacrylate(s) is selected from polymetylmethacrylate, polymethyl tert-butyl acrylate PtBMA, polyacrylic acid tert-butyl ester PtBA, Vinalac 5920 PnBMA or the positive butyl ester PnBA of polyacrylic acid.

2. the preparation method of hydrophilic-hydrophobic graft polymer according to claim 1, it is characterized in that the preparation of hydrophobicity macromolecular chain: with vinylbenzene or esters of acrylic acid hydrophobic monomer is polymerization single polymerization monomer, select to contain the haloalkane or the aromatic sulfonyl chloride class material of inducing the conjugation group on the α position and make initiator, in the presence of coordination agent and catalyzer, carry out atom transition free radical polymerization reaction and make polystyrene or the polyacrylate(s) macromolecular chain that end contains halogen atom, polymerization single polymerization monomer: coordination agent: catalyzer: the mole proportioning of initiator is decided to be n: 1: 2: 1, mol ratio 20≤n≤200 that change monomer and initiator reach the relative molecular mass of control macromolecular chain, temperature of reaction is controlled at 80～130 ℃, reaction times is controlled to be 6～12 hours, coordination agent is a Tetramethyl Ethylene Diamine, five methyl diethylentriamine or bipyridine, catalyzer are cuprous chloride, cuprous bromide or iron protochloride.

3. the preparation method of hydrophilic-hydrophobic graft polymer according to claim 1 is characterized in that described initiator is alpha-brominated methyl propionate or ethyl-alpha-bromopropionate.

4. the preparation method of hydrophilic-hydrophobic graft polymer according to claim 1, it is characterized in that hydrolysis prepares wetting ability macromolecular chain PMAA: PtBMA is hydrolyzed, select 1, the 4-dioxane is dissolution with solvents PtBMA, adding a certain amount of concentrated hydrochloric acid refluxes, hydrolysising reacting temperature is controlled at 75～95 ℃, reaction times is controlled to be 12～40 hours, reaction finishes, drip hexanaphthene or normal hexane and make it precipitation, suction filtration, obtain hydrolysate, concentrated hydrochloric acid and 1, the volume ratio of 4-dioxane is 1: 10～1: 20.

5. the preparation method of hydrophilic-hydrophobic graft polymer according to claim 1, it is characterized in that hydrolysis prepares wetting ability macromolecular chain PAA: PtBA is hydrolyzed, selecting methyl-sulphoxide is dissolution with solvents PtBA, adding a certain amount of concentrated hydrochloric acid refluxes, hydrolysising reacting temperature is controlled at 85～95 ℃, reaction times is controlled to be 20～40 hours, reaction finishes, drip sherwood oil or normal hexane and make it precipitation, suction filtration, obtain hydrolysate, the volume ratio of concentrated hydrochloric acid and methyl-sulphoxide is 1: 10～1: 20.

6. the preparation method of hydrophilic-hydrophobic graft polymer according to claim 1, it is characterized in that the synthetic of hydrophilic-hydrophobic graft polymer: in reaction vessel, add PMAA or PAA successively, a certain amount of hydrophobicity macromolecular chain, with N, dinethylformamide is a solvent, stir fully, the triethylamine that the 1-5 of adding hydrophobicity macromolecular chain mole number doubly measures, temperature of reaction is controlled to be 30～50 ℃, and the reaction times is controlled to be 6～20 hours, reaction finishes the back naturally cooling, leave standstill, collect layer oily matter, use a certain amount of chloroform or tetrahydrofuran (THF) repetitive scrubbing again, remove unreacted polymer, obtain hydrophilic-hydrophobic graft polymer.

7. use the hydrophilic-hydrophobic graft polymer of the described preparation method's preparation of claim 1, it is characterized in that hydrophilic-hydrophobic graft polymer is selected from: polymethyl acrylic acid-g-polystyrene graft polymkeric substance, polymethyl acrylic acid-g-polyacrylic acid tert-butyl ester graftomer, polymethyl acrylic acid-g-polymethyl tert-butyl acrylate graftomer, polymethyl acrylic acid-g-polymethylmethacrylate graftomer, polymethyl acrylic acid-g-Vinalac 5920 graftomer, polyacrylic acid-g-polystyrene graft polymkeric substance, polyacrylic acid-g-polyacrylic acid tert-butyl ester graftomer, polyacrylic acid-g-polymethyl tert-butyl acrylate graftomer, polyacrylic acid-g-polymethylmethacrylate graftomer, or polyacrylic acid-g-Vinalac 5920 graftomer.