阅读说明：本技术 非均相羧酸锌催化混合单体合成嵌段聚酯的方法 (Method for synthesizing block polyester by heterogeneous zinc carboxylate catalytic mixed monomer ) 是由 宋鹏飞 王俐艳 马玮 马菊萍 杨钊 姬维刚 于 2020-12-18 设计创作，主要内容包括：本发明公开了一种非均相羧酸锌催化混合单体合成嵌段聚酯的方法,分别取邻苯二甲酸酐、丙交酯和用4#分子筛泡过的环氧丙烷；再取有机溶剂和催化剂；真空干燥催化剂,冷却至室温,加入邻苯二甲酸酐和丙交酯；密封,抽真空,加入环氧丙烷,再加入有机溶剂,在一定温度下反应,冷却至室温,得粗产品；氯仿完全溶解粗产品,离心,用盐酸酸化的甲醇溶液纯化,制得嵌段聚合物。该合成方法制备方法简单,无毒且绿色环保,后处理简单,聚合过程有序列控制性,最终得到嵌段聚合物。(The invention discloses a method for synthesizing block polyester by heterogeneous zinc carboxylate catalytic mixed monomers, which comprises the steps of respectively taking phthalic anhydride, lactide and propylene oxide which is soaked by a 4A molecular sieve; taking an organic solvent and a catalyst; vacuum drying the catalyst, cooling to room temperature, and adding phthalic anhydride and lactide; sealing, vacuumizing, adding propylene oxide, adding an organic solvent, reacting at a certain temperature, and cooling to room temperature to obtain a crude product; the crude product was completely dissolved in chloroform, centrifuged, and purified with a methanol solution acidified with hydrochloric acid to obtain a block polymer. The synthesis method is simple in preparation method, non-toxic, green and environment-friendly, simple in post-treatment and sequence controllability in the polymerization process, and finally the block polymer is obtained.)

1. A method for synthesizing block polyester by using heterogeneous zinc carboxylate to catalyze mixed monomers is characterized by comprising the following steps:

respectively taking phthalic anhydride, lactide and propylene oxide according to the molar ratio of 1: 0.5-1: 2; respectively taking the organic solvent and the catalyst according to the proportion that 0.5g of phthalic anhydride needs 2.5mL of the organic solvent and 0.1-0.2 g of the catalyst; drying the catalyst at 100-120 ℃ in vacuum, cooling to room temperature, and adding phthalic anhydride and lactide; sealing, vacuumizing, adding propylene oxide, adding an organic solvent, reacting for 4-9 hours at the temperature of 100-120 ℃, and cooling to room temperature to obtain a crude product; the crude product was completely dissolved in chloroform, centrifuged, and purified with a methanol solution acidified with hydrochloric acid to obtain a block polymer.

2. The method of claim 1, wherein the catalyst is a heterogeneous zinc carboxylate.

3. The method of claim 1, wherein the organic solvent is toluene.

4. The method for synthesizing a block polyester using heterogeneous zinc carboxylate catalyzed mixed monomers as claimed in claim 1, wherein the propylene oxide is a 4 a molecular sieve bubble propylene oxide.

Technical Field

The invention belongs to the technical field of high polymer material synthesis, and relates to a method for generating a block polymer by catalyzing mixed monomers to polymerize through heterogeneous carboxylic acid.

Background

Currently, ring-opening alternating copolymerization (ROAC) of epoxides with cyclic anhydrides has been considered a promising approach to diversify polyester synthesis. In addition, ring-opening polymerization (ROP) of Lactide (LA) is an effective method for producing polylactic acid (PLA) having excellent biodegradability, biocompatibility and mechanical properties. A number of catalysts are used to produce polyesters and PLA by ROAC and ROP, including metal complexes, quaternary onium salts, phosphazenes, lewis equivalents, and the like. Due to their special properties, block copolymers have received much attention. There are many applications in the fields of medicine, nanotechnology, lithography, photonics, and electronics. A series of successful block copolymer synthesis methods exist in the prior art. In general, these are suitable for in situ processes or for post-polymerization modification. In situ processes typically use living polymerization processes that build individual blocks by sequential addition of monomers. The in situ method is superior to the post polymerization coupling because it reduces problems with intermediate purification steps and low reactivity of the polymer chain ends in the coupling reaction. However, the selective conversion of mixed monomers into well-defined and useful products remains a major challenge for sustainable catalysis.

In recent reports, some groups have used various catalysts to obtain block copolymers from monomer mixtures, such as metalloporphyrins, metal-Salen, phosphazenes, ionic liquids, and like homogeneous catalysts. However, homogeneous catalysts are known to be difficult to work up, which undoubtedly increases costs and is laborious.

Disclosure of Invention

The invention aims to provide a method for synthesizing a block polymer by catalyzing with a heterogeneous zinc carboxylate catalyst, which has simple post-treatment.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a method for synthesizing a block polymer by using a heterogeneous zinc carboxylate catalyst comprises the following specific steps:

respectively taking phthalic anhydride, lactide and propylene oxide according to the molar ratio of 1: 0.5-1: 2; respectively taking the organic solvent and the catalyst according to the proportion that 2.5mL of organic solvent and 0.1-0.2 g of catalyst are needed for 0.5g of phthalic anhydride, adding the catalyst into a reaction bottle, drying in vacuum at the temperature of 100-120 ℃ for 10-12 h, cooling to room temperature, and placing the phthalic anhydride and the lactide into the cooled reaction bottle; sealing the reaction bottle, vacuumizing for 30-40 min, adding propylene oxide into the reaction bottle by using a disposable syringe (purchased in the market), adding an organic solvent, reacting for 4-9 h at the temperature of 100-120 ℃, and cooling to room temperature to obtain a crude product; the crude product was completely dissolved with chloroform, centrifuged at 8500rpm for 10 minutes to remove the catalyst, and purified with a methanol solution acidified with hydrochloric acid to obtain a block polymer.

The catalyst adopts heterogeneous zinc carboxylate catalyst, and the organic solvent adopts toluene.

The chemical formula of the synthetic method is as follows:

according to the synthesis method, the heterogeneous zinc carboxylate catalyst is applied to the copolymerization reaction of the epoxide, the cyclic anhydride and the lactide to prepare the block polyester, the catalytic system is non-toxic, easy to post-treat, green and environment-friendly, and the use possibility of the block polymer in the fields of biomedicine and the like is improved.

According to the synthesis method, propylene oxide, phthalic anhydride and lactide are selectively polymerized under the condition that heterogeneous zinc carboxylate is used as a catalyst and an organic solvent is used as a solvent, the selective polymerization means that only propylene oxide and phthalic anhydride are polymerized to generate a PPAPO-co-PPO part in one-pot polymerization of mixed monomers, LA begins to participate in polymerization after PA is reacted, and finally block polyester (PPAPO-co-PPO) -b-PLA is generated; the used catalyst is a heterogeneous zinc carboxylate catalyst, and the catalyst is convenient to post-treat, non-toxic and low in cost. The present invention describes a route to block polyesters from monomer mixtures using heterogeneous catalysts. Block polymers are obtained by ROP bridging LA and ROAC reaction between epoxide and anhydride. Although the synthesized block polymer contains polyether segments, the catalyst still has good sequence control on the polymerization process, and the whole polymerization process can be clearly shown by the figure 2.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum of a block polyester prepared in example 1 of the present invention.

FIG. 2 is a nuclear magnetic hydrogen spectrum of a crude block polyester prepared in example 1 of the present invention at different reaction time periods.

FIG. 3 is a nuclear magnetic hydrogen spectrum of a crude block polyester prepared in example 2 of the present invention at different reaction time periods.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

Example 1

Respectively taking phthalic anhydride, lactide and epoxypropane soaked by a 4A molecular sieve according to the mol ratio of 1: 2; taking toluene and heterogeneous zinc carboxylate according to the proportion that 0.5g of phthalic anhydride needs 2.5mL of toluene and 0.1g of heterogeneous zinc carboxylate, respectively, adding the heterogeneous zinc carboxylate into a reaction bottle, drying in vacuum at the temperature of 120 ℃ for 12h, cooling to room temperature, and placing the phthalic anhydride and the lactide into the cooled reaction bottle; sealing the reaction bottle, vacuumizing for 30min, adding propylene oxide into the reaction bottle by using a disposable syringe (purchased from the market), adding toluene, reacting for 9h at the temperature of 120 ℃, and cooling to room temperature to obtain a crude product; the crude product was completely dissolved with chloroform, centrifuged at 8500rpm for 10 minutes to remove heterogeneous zinc carboxylate, and purified with a methanol solution acidified with hydrochloric acid to obtain a block polymer.

The nuclear magnetic hydrogen spectrum of the block polyester obtained in example 1 is shown in FIG. 1. In the figure, a, b, c, d and e are respectively the peak of the PPAPO chain segment in the block polyester; f and g are the peak of the polyether PPO chain segment; h and i are the peak of PLA chain segment in the block polyester, which shows that the block polyester is successfully synthesized.

The nuclear magnetic hydrogen spectrum of the crude product obtained in example 1 is shown in FIG. 2. In the reaction process with the time of 9h, the PA monomer (8.05-7.85 ppm) is continuously consumed along with the increase of the reaction time, the PPAPO (7.75-7.40 ppm) is continuously generated, and the LA monomer (5.07-5.00 ppm) is not converted until the PA monomer is completely consumed. PA was just converted at 7h, after 7h, LA monomer began to convert to PLA (5.24-5.12 ppm), and polyether PPO (3.99-3.32 ppm) was found to be present at the first stage of the reaction, PPPO formation. The above experimental results demonstrate that when a heterogeneous zinc carboxylate catalyst is used to catalyze the polymerization of mixed monomers of PA, PO and LA, selective copolymerization is achieved, and finally block polyester containing a small amount of ether is generated.

Example 2

Respectively taking phthalic anhydride, lactide and propylene oxide soaked by a 4A molecular sieve according to the mol ratio of 1: 0.5: 2; taking toluene and heterogeneous zinc carboxylate according to the proportion that 0.5g of phthalic anhydride needs 2.5mL of toluene and 0.2g of heterogeneous zinc carboxylate, respectively, adding the heterogeneous zinc carboxylate into a reaction bottle, drying in vacuum at the temperature of 120 ℃ for 10h, cooling to room temperature, and placing the phthalic anhydride and the lactide into the cooled reaction bottle; sealing the reaction bottle, vacuumizing for 40min, adding propylene oxide into the reaction bottle by using a disposable syringe (purchased from the market), adding toluene, reacting for 4h at the temperature of 120 ℃, and cooling to room temperature to obtain a crude product. The crude product was completely dissolved with chloroform, centrifuged at 8500rpm for 10 minutes to remove the catalyst, and purified with a methanol solution acidified with hydrochloric acid to obtain a block polymer.

Example 3

Respectively taking phthalic anhydride, lactide and propylene oxide soaked by a 4A molecular sieve according to the mol ratio of 1: 0.5: 2; taking toluene and heterogeneous zinc carboxylate according to the proportion that 0.5g of phthalic anhydride needs 2.5mL of toluene and 0.2g of heterogeneous zinc carboxylate, respectively, adding the heterogeneous zinc carboxylate into a reaction bottle, drying in vacuum at the temperature of 120 ℃ for 10h, cooling to room temperature, and placing the phthalic anhydride and the lactide into the cooled reaction bottle; sealing the reaction bottle, vacuumizing for 40min, adding propylene oxide into the reaction bottle by using a disposable syringe (purchased from the market), adding toluene, reacting for 8h at the temperature of 120 ℃, and cooling to room temperature to obtain a crude product. The crude product was completely dissolved with chloroform, centrifuged at 8500rpm for 10 minutes to remove the catalyst, and purified with a methanol solution acidified with hydrochloric acid to obtain a block polymer.

The crude products obtained in example 2 and example 3 were subjected to nuclear magnetic hydrogen spectrum characterization, yielding fig. 3. As the rule of FIG. 2 is the same, only PPAPO and a small amount of polyether are generated in 4h of reaction, PPAPO (7.75-7.40 ppm) is continuously generated while PA monomer (8.05-7.85 ppm) is continuously consumed, and LA monomer (5.07-5.00 ppm) is not converted until PA monomer is completely consumed. Just after the PA conversion is complete, the LA monomer begins to convert to PLA (5.24-5.12 ppm) until 8hLA is also reacted to completion, eventually producing a block polyester containing a small amount of ether.

Example 4

Respectively taking phthalic anhydride, lactide and propylene oxide soaked by a 4A molecular sieve according to the mol ratio of 1: 0.75: 2; taking toluene and heterogeneous zinc carboxylate according to the proportion that 0.5g of phthalic anhydride needs 2.5mL of toluene and 0.15g of heterogeneous zinc carboxylate, respectively, adding the heterogeneous zinc carboxylate into a reaction bottle, drying in vacuum at the temperature of 100 ℃ for 11h, cooling to room temperature, and placing the phthalic anhydride and the lactide into the cooled reaction bottle; sealing the reaction bottle, vacuumizing for 35min, adding propylene oxide into the reaction bottle by using a disposable syringe (purchased from the market), adding toluene, reacting for 7h at the temperature of 100 ℃, and cooling to room temperature to obtain a crude product. The crude product was completely dissolved with chloroform, centrifuged at 8500rpm for 10 minutes to remove the catalyst, and purified with a methanol solution acidified with hydrochloric acid to obtain a block polymer.

Example 5

Respectively taking phthalic anhydride, lactide and propylene oxide soaked by a 4A molecular sieve according to the mol ratio of 1: 0.5: 2; taking toluene and heterogeneous zinc carboxylate according to the proportion that 0.5g of phthalic anhydride needs 2.5mL of toluene and 0.1g of heterogeneous zinc carboxylate, respectively, adding the heterogeneous zinc carboxylate into a reaction bottle, drying in vacuum at the temperature of 110 ℃ for 10h, cooling to room temperature, and placing the phthalic anhydride and the lactide into the cooled reaction bottle; sealing the reaction bottle, vacuumizing for 35min, adding propylene oxide into the reaction bottle by using a disposable syringe (purchased from the market), adding toluene, reacting for 5h at the temperature of 11 ℃, and cooling to room temperature to obtain a crude product. The crude product was completely dissolved with chloroform, centrifuged at 8500rpm for 10 minutes to remove the catalyst, and purified with a methanol solution acidified with hydrochloric acid to obtain a block polymer.