阅读说明：本技术 一种生物降解材料多嵌段聚酯及其制备方法 (Biodegradable material multi-block polyester and preparation method thereof ) 是由 庞煊 *** 段然龙 张涵 孙志强 周延川 陈学思 于 2020-07-03 设计创作，主要内容包括：本发明提供了一种生物降解材料多嵌段聚酯及其制备方法,方法包括以下步骤：在催化剂作用下,丙交酯、邻苯二甲酸酐和环氧环己烷在溶剂中进行开环共聚合反应,得到多嵌段聚酯；所述催化剂为具有式I结构的希夫碱锰化合物。本发明提供的方法采用具有式I结构的希夫碱锰化合物用于催化丙交酯、酸酐和环氧环己烷的开环共聚合,该催化剂具有NNOO三齿配位能力,能够形成一个金属活性中心结合位点,是一种四配位希夫碱锰催化剂,对两种不同类型的开环聚合都具有比较好的活性,并且对单体有很高的选择性,可以实现可调控的多嵌段聚合反应。本申请通过三次的酸酐添加能够得到7段的聚丙交酯-聚酸酐环氧共聚物,最高分子量能够达到47kg/mol。(The invention provides a biodegradable material multi-block polyester and a preparation method thereof, wherein the method comprises the following steps: under the action of a catalyst, lactide, phthalic anhydride and cyclohexene oxide are subjected to ring-opening copolymerization reaction in a solvent to obtain multi-block polyester; the catalyst is a Schiff base manganese compound with a structure shown in a formula I. The method provided by the invention adopts the Schiff base manganese compound with the structure of formula I to catalyze the ring-opening copolymerization of lactide, anhydride and cyclohexene oxide, the catalyst has NNOO tridentate coordination capacity, can form a metal active center binding site, is a four-coordination Schiff base manganese catalyst, has good activity for two different types of ring-opening polymerization, has high selectivity for monomers, and can realize adjustable multi-block polymerization reaction. According to the preparation method, 7 sections of polylactide-polyanhydride epoxy copolymer can be obtained through three times of anhydride addition, and the highest molecular weight can reach 47 kg/mol.)

1. A preparation method of biodegradable material multi-block polyester comprises the following steps:

under the action of a catalyst, lactide, phthalic anhydride and cyclohexene oxide are subjected to ring-opening copolymerization reaction in a solvent to obtain multi-block polyester;

the catalyst is a Schiff base manganese compound with a structure shown in formula I:

wherein Y is selected from linear alkyl of C2-C4, cycloalkyl of C4-C7 or

And R is selected from-H, halogen or C1-C5 alkyl.

2. The preparation method according to claim 1, wherein the temperature of the ring-opening copolymerization reaction is 75-85 ℃ and the time is 24-60 h.

3. The production method according to claim 1, wherein the mass ratio of the catalyst, lactide, and phthalic anhydride is 1:100 to 500.

4. The method according to claim 1, wherein the solvent is selected from phthalic anhydride or toluene.

5. The method according to claim 1, wherein the ratio of the amount of the catalyst substance to the volume of the solvent is 0.1mmol (15-40) mL.

6. The method of claim 1, wherein R is-H or t-butyl;

y is selected from

7. A biodegradable material multi-block polyester prepared by the preparation method of any one of claims 1 to 6.

Technical Field

The invention belongs to the technical field of polymers, and particularly relates to a biodegradable material multi-block polyester and a preparation method thereof.

Background

Many of the biosyntheses in nature are as follows: DNA, proteins, etc., have complex and precise regulatory processes that are not available for artificial synthesis, which is also a key challenge in current polymer synthesis chemistry.

The activity of the polymerization reaction process and the polymer composition are controlled, diversified polymer components or structures are customized according to needs to meet the requirements of the industry on thermal and mechanical properties, the degradable polyester mainly prepared by ring-opening polymerization (ROP) or ring-opening copolymerization (ROOP) of cyclic monomers is an important substitute of petroleum-derived materials, in practical application, crystalline PLA materials have high melting points and can meet the application in many aspects, but the defects of hardness and brittleness exist, and the epoxy and anhydride copolymer can obtain materials with good flexibility through the selection of the monomers. Compared with the direct physical blending of several materials, the chemical copolymer has good compatibility, the copolymer material obtained by means of block or random copolymerization and the like has better physical and processing properties, and can be used as a compatibilizer to modify physical blends of different materials. Because the micro-segment structure of the polymer has a great influence on the physical properties of the polymer, and a controllable polymerization catalytic system capable of regulating and controlling the molecular linkage of the polymer becomes a hotspot of research, a controllable multi-block polymerization catalytic system aiming at multi-monomer components is developed.

Recently, the work on anhydride/epoxide/LA switchable copolymers, which are coming in succession, is considered as a promising approach for diversifying polyesters with good biocompatibility and mechanical properties, but the preparation of multiblock polyesters for precise control of block sequence and polymer molecular weight is still limited. In previous work, multi-block polyesters were produced primarily by chain extension of polyester polyols, with the addition of chain transfer agents increasing the number of blocks, but disadvantageously too many chain transfer reactions only produce polyol oligomers of relatively low molecular weight. In addition, in organometallic catalysts such as Salen Cr or Al systems, a cocatalyst is required to initiate the ring opening process, which causes difficulties in determining the structure of the active species, and also the limitation of the initiating group and side reactions affect the final effect of the polymerization reaction.

Disclosure of Invention

In view of the above, the present invention provides a biodegradable material multi-block polyester and a preparation method thereof, which can prepare a controllable multi-block polyester without adding a chain transfer agent and a cocatalyst.

The invention provides a preparation method of biodegradable material multi-block polyester, which comprises the following steps:

under the action of a catalyst, lactide, phthalic anhydride and cyclohexene oxide are subjected to ring-opening copolymerization reaction in a solvent to obtain multi-block polyester;

the catalyst is a Schiff base manganese compound with a structure shown in formula I:

wherein Y is selected from linear alkyl of C2-C4, cycloalkyl of C4-C7 or

And R is selected from-H, halogen or C1-C5 alkyl.

Preferably, the temperature of the ring-opening copolymerization reaction is 75-85 ℃, and the time is 24-60 h.

Preferably, the mass ratio of the catalyst, lactide and phthalic anhydride is 1: 100-500.

Preferably, the solvent is selected from phthalic anhydride or toluene.

Preferably, the volume ratio of the substance of the catalyst to the solvent is 0.1mmol (15-40) mL.

Preferably, said R is-H or tert-butyl;

y is selected from

-CH₂-CH₂-CH₂-or-CH₂-CH₂-。

The invention provides a biodegradable material multi-block polyester, which is prepared by the preparation method of the technical scheme.

The invention provides a preparation method of biodegradable material multi-block polyester, which comprises the following steps: under the action of a catalyst, lactide, phthalic anhydride and cyclohexene oxide are subjected to ring-opening copolymerization reaction in a solvent to obtain multi-block polyester; the catalyst is a Schiff base manganese compound with a structure shown in a formula I. The method provided by the invention adopts the Schiff base manganese compound with the structure of formula I to catalyze the ring-opening copolymerization of lactide, anhydride and cyclohexene oxide, the catalyst has NNOO tridentate coordination capacity, can form a metal active center binding site, is a four-coordination Schiff base manganese catalyst, has good activity for two different types of ring-opening polymerization, has high selectivity for monomers, and can realize adjustable multi-block polymerization reaction. The experimental results show that: according to the preparation method, 7 sections of polylactide-polyanhydride epoxy copolymer can be obtained through three times of anhydride addition, and the highest molecular weight can reach 47 kg/mol.

Drawings

FIG. 1 is a schematic diagram of the reaction process of in situ IR monitoring of PA and LA in example 6 of the present invention;

FIG. 2 is a comparative nuclear magnetic hydrogen spectrum of PLA, PCHE and block copolymer of example 6 of the present invention;

FIG. 3 is a DOSY nuclear magnetic resonance comparison schematic diagram of the blend and the copolymer in example 6 of the invention.

Detailed Description

The invention provides a preparation method of biodegradable material multi-block polyester, which comprises the following steps:

under the action of a catalyst, lactide, phthalic anhydride and cyclohexene oxide are subjected to ring-opening copolymerization reaction in a solvent to obtain multi-block polyester;

the catalyst is a Schiff base manganese compound with a structure shown in formula I:

wherein Y is selected from linear alkyl of C2-C4, cycloalkyl of C4-C7 or

And R is selected from-H, halogen or C1-C5 alkyl.

In the invention, the catalyst is a Schiff base manganese compound with a structure shown in formula I, and the Schiff base manganese compound has NNOO tridentate coordination capacity, so that a metal active center binding site is formed, and the catalyst is a four-coordination Schiff base manganese catalyst. The Schiff base manganese compound has a high-activity manganese center, has relatively good activity for ring-opening polymerization and ring-opening copolymerization, has high selectivity for different monomers, and can realize controllable multi-block polymerization.

In the present invention, the preferred catalyst is prepared according to the following method:

reacting a Schiff base ligand with a structure shown in a formula II with manganese acetate tetrahydrate and lithium chloride in a solvent to obtain a Schiff base manganese compound with a structure shown in a formula I;

and R is selected from-H, halogen or C1-C5 alkyl.

In the present invention, the Schiff base ligand having the structure of formula II is preferably prepared according to the following method:

carrying out condensation reaction on a diamine compound with a structure in formula III and a salicylaldehyde compound with a structure in formula IV to obtain a Schiff base ligand with a structure in formula II;

r is selected from-H, halogen or C1-C5 alkyl; preferably, R is selected from-H or tert-butyl (tBu).

In the invention, the amino compound with the structure III is preferably selected from rac-1, 2-cyclohexanediamine, (S, S) -1, 2-cyclohexanediamine, (R, R) -1, 2-cyclohexanediamine, 1, 2-phenylenediamine, ethylenediamine or 1, 4-propylenediamine.

The salicylaldehyde compound with the structure of formula IV is preferably selected from 3, 5-di-tert-butyl salicylaldehyde or salicylaldehyde.

In the invention, preferably, the diamine compound with the structure of formula III is dissolved in ethanol, and the ethanol solution of the salicylaldehyde compound with the structure of formula IV is slowly dripped into the obtained diamine compound solution, heated and refluxed to carry out condensation reaction. In the invention, the mass concentration of the diamine compound with the structure of the formula III in the diamine compound solution is preferably 0.1 g/mL-0.5 g/mL, more preferably 0.15 g/mL-0.3 g/mL; in the ethanol solution of the salicylaldehyde compound, the mass concentration of the salicylaldehyde compound with the structure of formula IV is preferably 0.1 g/mL-0.5 g/mL, and more preferably 0.2 g/mL-0.4 g/mL.

In the invention, the mass ratio of the diamine compound with the structure III to the salicylaldehyde compound with the structure IV is preferably 1: 2-4, and more preferably 1: 2.

In the present invention, the condensation reaction is carried out under reflux conditions; the time of the condensation reaction is preferably 8-16 h, more preferably 11-13 h, and more preferably 12 h.

After the condensation reaction in the technical scheme is completed, the solvent in the obtained reaction solution is preferably removed, and the obtained reaction product is recrystallized to obtain the Schiff base ligand with the structure of formula II. The method for removing the solvent and recrystallizing is not particularly limited in the present invention, and the solvent removal and recrystallization method known to those skilled in the art can be used. According to the invention, the solvent in the reaction solution is preferably removed by rotary evaporation, and the obtained reaction solution is recrystallized by using a dichloromethane/ethanol mixed solvent to obtain the Schiff base ligand with the structure of formula II.

After the Schiff base ligand with the structure of the formula II is obtained, the Schiff base ligand with the structure of the formula II, manganese acetate tetrahydrate and lithium chloride react in a solvent to obtain the Schiff base manganese compound with the structure of the formula I. Preferably, under the protection of inert gas, mixing and stirring a solution of Schiff base ligand with a structure shown in formula II and a manganese acetate tetrahydrate solution, carrying out reflux reaction on the obtained mixed solution, and then continuously carrying out reflux reaction on the obtained mixed solution and lithium chloride to obtain the Schiff base manganese compound with a structure shown in formula I. In the invention, the mole ratio of the Schiff base ligand with the structure of formula II, manganese acetate tetrahydrate and lithium chloride is preferably 1:2: 3. The molar concentration of the solution of the Schiff base ligand with the structure of the formula II is preferably 0.5-2 mol/L, and more preferably 1-2 mol/L; the solvent in the manganese acetate solution is preferably ethanol; the molar concentration of the manganese acetate solution is preferably 0.5-2 mol/L, and more preferably 1-2 mol/L.

In the invention, the temperature of the reaction of the Schiff base ligand with the structure of formula II and manganese acetate is preferably 25-60 ℃; when the reaction solvent is ethanol, the most preferable reaction solvent is 80 ℃; the reaction time of the Schiff base ligand with the structure shown in the formula II and manganese acetate is preferably 2-3 h, and more preferably 10-12 h; the reaction time after addition of lithium chloride is preferably 1 h.

And after the reaction of the Schiff base ligand with the structure of the formula II, manganese acetate and lithium chloride is completed, removing volatile substances in the reaction solution to obtain the Schiff base manganese compound with the structure of the formula I. The method for removing the volatile substance in the present invention is not particularly limited, and a method for removing the volatile substance in the reaction system, which is well known to those skilled in the art, may be used. In the present invention, the obtained reaction solution is preferably evacuated to remove volatile substances therein, and the degree of vacuum of evacuation is preferably 0.05 to 0.5MPa, more preferably 0.1 to 0.3 MPa.

In the present invention, the sources of lactide and phthalic anhydride are not particularly limited, and commercially available products may be used, and in the present invention, it is preferable to recrystallize commercially available lactide and phthalic anhydride products and then perform a ring-opening polymerization reaction. The present invention may be carried out using a solvent capable of dissolving lactide, acid anhydride and catalyst, which is well known to those skilled in the art, and in the present invention, epoxycyclohexane or toluene.

The Schiff base manganese compound adopted in the method provided by the invention has higher reaction activity and less dosage during the catalytic polymerization reaction. In the present invention, the mass ratio of the catalyst, lactide, phthalic anhydride and cyclohexene oxide is 1:100 to 500:1000 to 2000, more preferably 1:100 to 400:1000 to 2000, and most preferably 1:100 to 300:1000 to 2000.

In the invention, the acid anhydride is polymerized with the lactide, and the lactide begins to react after the acid anhydride is completely polymerized. In the invention, the temperature of the ring-opening polymerization reaction is preferably 75-85 ℃, and more preferably 80 ℃. The time of the ring-opening polymerization reaction is preferably 24-60 h; the time of the ring-opening polymerization reaction of each lactide is preferably 0.5-2 h, and the time of the copolymerization reaction of each phthalic anhydride and cyclohexene oxide is preferably 9-30 h most preferably.

After the ring-opening polymerization reaction is finished, the obtained ring-opening polymerization reaction product is preferably dissolved by adopting trichloromethane, excessive ethanol is added to precipitate the polymer, and the polymer is obtained after the filtration and the drying. The invention has no special limit on the dosage of the trichloromethane, and the obtained reaction product can be dissolved; the method for filtering and drying is not particularly limited in the invention, and the technical scheme of filtering and drying which is well known by the technicians in the field can be adopted; in the invention, the drying is preferably vacuum drying, and the drying time is preferably 24-48 h, and most preferably 36 h.

The invention provides a biodegradable material multi-block polyester, which is prepared by the preparation method of the technical scheme.

The present invention preferably uses nuclear magnetic hydrogen and carbon spectra to analyze the polymer chain ends as described in the above schemes and uses diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY) to demonstrate that it is a copolymer rather than a blend.

In order to further illustrate the present invention, the following examples are given to describe the biodegradable material multi-block polyester and the preparation method thereof in detail, but they should not be construed as limiting the scope of the present invention.