CN109734830B

CN109734830B - Preparation method of polymethacrylate copolymer

Info

Publication number: CN109734830B
Application number: CN201811626733.0A
Authority: CN
Inventors: 陈扬; 陈志麟; 布明鹭; 雷彩红; 许进宝
Original assignee: Guangdong University of Technology
Current assignee: Guangdong University of Technology
Priority date: 2018-12-28
Filing date: 2018-12-28
Publication date: 2021-11-19
Anticipated expiration: 2038-12-28
Also published as: CN109734830A

Abstract

The invention belongs to the technical field of polymer synthesis, and discloses a preparation method of a polymethacrylate polymer. The method comprises the following operation steps: preparing polymethyl methacrylate by adopting traditional free radical polymerization; polymethyl methacrylate is used as a precursor, 1, 8-diazabicyclo [5.4.0] -undec-7-ene and 1,2, 4-triazole are used as catalysts, and different alcohols are added to carry out ester exchange reaction to synthesize the polymethacrylate copolymer. The invention takes polymethyl methacrylate as a precursor, the raw materials are cheap, different polymethacrylates can be directly prepared from polymethyl methacrylate by adding different alcohols, copolymers with different components can be obtained by changing the feed ratio, meanwhile, the reaction conditions are mild, some functionalized polymethyl methacrylate copolymers which can not be prepared by free radical polymerization can be obtained, the substrate inclusion is strong, and the invention has obvious economic benefit.

Description

Preparation method of polymethacrylate copolymer

Technical Field

The invention belongs to the technical field of polymer synthesis, and particularly relates to a preparation method of a polymethacrylate polymer.

Background

Methyl Methacrylate (MMA) is an important chemical raw material, and polymethyl methacrylate (PMMA) is a polymer formed by polymerizing methyl methacrylate as a monomer. The polymethacrylate polymer has excellent performances of low density, high mechanical strength, high light transmittance and the like, and is widely applied to the fields of aviation, automobiles, electronic instruments, optical instruments, medical appliances and the like. For example, polymethyl methacrylate-based organic glasses and polyhydroxyethyl methacrylate-based thermosetting coatings and adhesives are prepared.

The prior method for synthesizing the polymethacrylate copolymer generally utilizes two different methacrylate monomers for copolymerization, needs protection on groups sensitive to free radical polymerization, and then carries out deprotection operation after obtaining a polymer, thereby increasing the process cost and the experimental difficulty. Since the amount of polymethacrylate copolymers required is enormous, it would be extremely attractive to explore new methods for synthesizing polymethacrylate copolymers, and the present invention is directed to such methods.

Disclosure of Invention

In order to overcome the defects and shortcomings in the prior art, the invention aims to provide a preparation method of a polymethacrylate polymer.

The purpose of the invention is realized by the following technical scheme:

a preparation method of a polymethacrylate polymer comprises the following operation steps: preparing polymethyl methacrylate by adopting traditional free radical polymerization; polymethyl methacrylate is taken as a precursor, 1, 8-diazabicyclo [5.4.0] -undec-7-ene (DBU) and 1,2, 4-Triazole (TA) are taken as catalysts, and different alcohols are added for ester exchange reaction to synthesize the polymethacrylate copolymer.

The polymerization degree of the polymethyl methacrylate is 50, M_n＝5300，PDI＝1.47。

The alcohol is ethanol, propanol, isopropanol or propiolic alcohol.

The molar ratio of the catalyst to the polymethyl methacrylate is 0.8-4.5; the molar ratio of the 1, 8-diazabicyclo [5.4.0] -undec-7-ene to the 1,2, 4-triazole is (1-3): (1-1.5).

The transesterification reaction adopts more than one solvent of Toluene (TOL), Tetrahydrofuran (THF) and N, N' -Dimethylformamide (DMF), the reaction temperature is 25-100 ℃, and the reaction time is 12-48 h.

The solvent adopted in the ester exchange reaction is more than one of Tetrahydrofuran (THF) and N, N' -Dimethylformamide (DMF), the reaction temperature is 60 ℃, and the reaction time is 24 h.

The chemical reaction equation of the preparation method of the polymethacrylate polymer is shown as the following formula (I):

n is the degree of polymerization (50) of PMMA, M_n5300, PDI 1.47; x and y represent the polymerization degrees of different polymethacrylates in the copolymer obtained after transesterification, and (x + y) ═ n. R-OH represents different alcohols used for the transesterification reaction, and ethanol, propanol, isopropanol and propiolic alcohol are respectively used. 1, 8-diazabicyclo [5.4.0]]The-undec-7-ene (DBU) and the 1,2, 4-Triazole (TA) are a catalytic system for catalyzing the transesterification reaction.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the invention takes polymethyl methacrylate as a precursor, the raw materials are cheap, different polymethacrylates can be directly prepared from polymethyl methacrylate by adding different alcohols, copolymers with different components can be obtained by changing the feed ratio, meanwhile, the reaction conditions are mild, some functionalized polymethyl methacrylate copolymers which can not be prepared by free radical polymerization can be obtained, the substrate inclusion is strong, and the invention has obvious economic benefit.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto. The experimental methods used in the following examples are, unless otherwise specified, all conventional methods, and the raw materials, reagents and the like used are, unless otherwise specified, all commercially available raw materials and reagents.

Example 1:

(1) synthetic PMMA₅₀Homopolymers

A Schlenk bottle equipped with a stirrer was charged with methyl methacrylate (10mmol,1.0g), azobisisobutyronitrile (0.1mmol,4.1mg) and 3mL of tetrahydrofuran, and then "freeze-evacuated-thawed" twice, thawed(ii) a And (3) putting the Schlenk bottle into an oil bath pan with the set temperature, and reacting for 6 h. After the reaction is finished, putting the Schlenk bottle into the lower layer of a refrigerator for 5min, precipitating n-hexane to obtain a white solid, and drying in vacuum to obtain a polymer with a chemical structure¹The structure was confirmed by H NMR, and the data for characterization were as follows. The molecular weight and molecular weight distribution of the polymer were determined by gel chromatography (GPC) using monodisperse polystyrene as a calibration curve.

¹H NMR(CDCl₃400MHz, chemical shift delta (ppm) ~ 1.22ppm (-CH)₂C(CH₃)COOCH₃),～1.85ppm(-CH₂C(CH₃)-),～3.58ppm(-CH₂C(CH₃)COOCH₃)。

(2) Synthesis of polymethyl methacrylate-co-polyethyl methacrylate (P (MMA-co-EMA))

Mixing PMMA (0.10g,1mmol of MMA), ethanol (0.14g,3mmol), DBU (0.152g,1mmol), TA (0.19g,3mmol) and 3mL of DMF, carrying out transesterification reaction at the temperature of 60 ℃ for 24h, and after the reaction is finished, using a methanol/water mixture as a precipitating agent to obtain a white solid, namely the copolymer polymethyl methacrylate-co-polyethyl methacrylate (P (MMA-co-EMA)). Through nuclear magnetic analysis, the molar mass ratio of MMA to EMA in the copolymer is found to be 4/6, which indicates that 60% of MA in the original precursor homopolymer PMMA undergoes transesterification under the DBU/TA catalysis condition; m of the copolymer was found by GPC analysis_nFurther evidence of transesterification of MA in the homopolymer was found to be 6000 and PDI 1.47. The method is characterized in that DBU/TA is used as a catalytic system, PMMA is used as a precursor, and the random copolymer of P (MMA-co-EMA) can be conveniently obtained by adding ethanol. The structural characterization data is as follows:

¹H NMR(CDCl₃400MHz, chemical shift delta (ppm) ~ 1.22ppm (-CH)₂C(CH₃)COOCH₃,-CH₂C(CH₃)COOCH₂CH₃),～1.85ppm(-CH₂C(CH₃)-),～3.58ppm(-CH₂C(CH₃)COOCH₃),～3.20ppm(-CH₂C(CH₃)COOCH₂CH₃).

Example 2

Synthesis of P (MMA-co-EMA) random copolymer

The transesterification reaction temperature was changed to 25 ℃ and other conditions were the same as those for the synthesis of the P (MMA-co-EMA) random copolymer in example 1, and by analyzing the polymer, it was found that only 25% of MA monomer was transesterified, and the results of comparative example 1 demonstrated that the reaction temperature was increased to facilitate the transesterification reaction.

Example 3

Synthesis of P (MMA-co-EMA) random copolymer

The transesterification reaction temperature was changed to 45 ℃ and other conditions were the same as those for the synthesis of a P (MMA-co-EMA) random copolymer in example 1, and by analyzing the polymer, it was found that 45% of MA monomer was transesterified, and the results of comparative example 1 show that the reaction temperature was increased to facilitate the transesterification reaction.

Example 4

Synthesis of P (MMA-co-EMA) random copolymer

The transesterification reaction temperature was changed to 100 ℃ and other conditions were the same as those for the synthesis of the P (MMA-co-EMA) random copolymer in example 1, and by analyzing the polymer, it was found that 70% of the MA monomer was transesterified, and the results of comparative example 1 show that the reaction temperature was increased to facilitate the transesterification reaction.

Example 5

Synthesis of P (MMA-co-EMA) random copolymer

The transesterification reaction time was changed to 12 hours, and other implementation conditions were the same as those for the P (MMA-co-EMA) random copolymer synthesized in example 1, and by analyzing the polymer, it was found that 40% of MA monomer was transesterified, and the increase in the reaction time was more advantageous than that in comparative example 1.

Example 6

Synthesis of P (MMA-co-EMA) random copolymer

The transesterification reaction time was changed to 36 hours, and other conditions were the same as those for the synthesis of the P (MMA-co-EMA) random copolymer in example 1. by analyzing the polymer, it was found that 65% of MA monomer was transesterified, and the prolonged reaction time was improved in favor of the transesterification reaction in comparative example 1, but the increase in transesterification was small in comparison with example 1.

Example 7

Synthesis of P (MMA-co-EMA) random copolymer

The transesterification reaction time was changed to 48 hours, and other implementation conditions were the same as those for the P (MMA-co-EMA) random copolymer synthesized in example 1, and it was found by analyzing the polymer that 67% of MA monomer was transesterified, and the increase in the reaction time was more advantageous than that in comparative example 1, but the transesterification was not increased much even when the reaction time was increased by 24 hours.

Examples 8 to 12

Synthesis of P (MMA-co-EMA) random copolymer

Compared with the example 1, the main difference of the examples 8-12 lies in the different ratios of the catalyst TA and DBU, and the experimental results of preparing the P (MMA-co-EMA) random copolymer by using PMMA as a precursor through ester exchange reaction under the different DBU/TA ratio conditions are listed in the table 1.

TABLE 1

The data in Table 1 show that the transesterification reaction at 60 ℃ and 24h is the most and the increase in the number average molecular weight with respect to the PMMA precursor is the most when the DBU/TA molar mass ratio is 3/1.

Example 13

Synthesis of polymethyl methacrylate-co-Polypropylene methacrylate (P (MMA-co-PMA))

The ethanol was changed to propanol (0.17g,3mmol) and other conditions were the same as those for the synthesis of a P (MMA-co-EMA) random copolymer in example 1, and by analyzing the resulting polymer, we found that the final product was a random copolymer of PMMA and PPMA, indicating that a transesterification reaction occurred under these conditions.

Example 14

Synthesis of polymethyl methacrylate-co-isopropyl polymethacrylate (P (MMA-co-iPMA))

The ethanol was changed to isopropanol (0.18g,3mmol) and the other conditions were the same as those for the synthesis of a P (MMA-co-EMA) random copolymer in example 1, and by analyzing the resulting polymer, we found that the final product was a random copolymer of PMMA and PiPMA, indicating that the transesterification reaction occurred under these conditions.

Comparative example 1

Synthesis of polymethyl methacrylate-co-isopropyl polymethacrylate (P (MMA-co-tBMA))

The ethanol was changed to t-butanol (0.22g,3mmol) and other conditions were the same as those for the synthesis of a P (MMA-co-EMA) random copolymer in example 1, and by analyzing the resulting polymer, we found that the final product was a PMMA homopolymer, indicating that transesterification did not occur under these conditions.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. The preparation method of the polymethacrylate copolymer is characterized by comprising the following operation steps: preparing polymethyl methacrylate by adopting traditional free radical polymerization; taking polymethyl methacrylate as a precursor, taking 1, 8-diazabicyclo [5.4.0] -undec-7-ene and 1,2, 4-triazole as catalysts, adding different alcohols for ester exchange reaction, and synthesizing a polymethacrylate copolymer; the alcohol is ethanol, propanol, isopropanol or propiolic alcohol.

2. The method of claim 1, wherein: the polymerization degree of the polymethyl methacrylate is 50,M _n= 5300，PDI = 1.47。

3. the method of claim 1, wherein: the molar ratio of the catalyst to the polymethyl methacrylate is 0.8-4.5; the molar ratio of the 1, 8-diazabicyclo [5.4.0] -undec-7-ene to the 1,2, 4-triazole is (1-3): (1-1.5).

4. The method of claim 1, wherein: the transesterification reaction adopts more than one solvent of toluene, tetrahydrofuran and N, N' -dimethylformamide, the reaction temperature is 25-100 ℃, and the reaction time is 12-48 h.

5. The method of claim 4, wherein: the solvent adopted in the ester exchange reaction is more than one of tetrahydrofuran and N, N' -dimethylformamide, the reaction temperature is 60 ℃, and the reaction time is 24 hours.