CN108503811B

CN108503811B - Polymer for endowing polylactic acid with shape memory

Info

Publication number: CN108503811B
Application number: CN201810382287.7A
Authority: CN
Inventors: 宋晓峰; 任亚君; 王磊; 韩立彬; 周琦峰; 胡洪涛
Original assignee: Changchun University of Technology
Current assignee: Changchun University of Technology
Priority date: 2018-04-26
Filing date: 2018-04-26
Publication date: 2020-08-07
Anticipated expiration: 2038-04-26
Also published as: CN108503811A

Abstract

The invention relates to a four-arm polymer for endowing polylactic acid (P L A) with shape memory, which takes tetramethyltetravinylcyclotetrasiloxane (D4 vi) as a core, a support arm contains Allyl Glycidyl Ether (AGE) chain segment, Polytetrahydrofuran (PTMG) block and polycaprolactone (PC L) block, wherein the PTMG block can improve the toughness and hydrophilicity of P L A, the low glass transition temperature of the PTMG block can realize melting and recrystallization processes at low temperature, the PC L block can greatly improve the compatibility of the PTMG block with P L A and avoid phase separation, the four-arm polymer can realize melting and recrystallization at low temperature (20-50 ℃) to endow P L A with shape memory effect, the shape memory recovery time is short, the four-arm polymer is simple and efficient to prepare, the toughness of P L A can be improved, the processing temperature of the four-arm polymer can be greatly reduced, and the four-arm polymer has the shape memory function.

Description

Polymer for endowing polylactic acid with shape memory

Technical Field

The invention relates to the field of shape memory of P L A, in particular to a four-arm polymer which takes cyclosiloxane as a central point, PTMG as a soft block and PC L as a compatibilization block, and the polymer and P L A blended composite material has a shape memory function.

Background

The P L A is an ideal green high polymer material, is in a plastic state, has high glass transition temperature, high processing temperature and high brittleness, is easy to crack in the using process and cannot be reused.

According to different environmental conditions for realizing the memory function, the memory material can be divided into a temperature-sensitive type, a photosensitive type, an acid-base sensitive type and other memory materials, and the most important memory materials in the current research and application are thermotropic shape memory polymer materials.

Disclosure of Invention

In order to overcome the existing technical defects, the invention provides a polymer which can enable P L A to have shape memory, has short shape recovery time, can avoid the phase separation problem and effectively improves the toughness of P L A.

The technical scheme of the invention is as follows: PTMG (PTMG) with cyclosiloxane as centerT _g= -76 ℃ as soft block, PC L: (C:)TgA four-arm polymer with a compatibilizing block at = -60 ℃P LL A: (T _g=62 ℃), the shape memory of thermotropic P L a composite material is achieved due to the glass transition temperature of the synthetic polymer being much different from that of P L a.

The central structure of the four-arm polymer:

the structure of the PC L compatibilization block on the four-arm polymer molecular support arm is as follows:

and n is an integer greater than 1.

The structure of the PTMG soft block on the four-arm polymer molecule support arm is as follows:

m is an integer greater than 1.

Drawings

FIG. 1 is a NMR spectrum of a four-arm polymer.

As shown in figure 1, in the nuclear magnetic spectrum of D4vi-AGE-PTMG-PC L, (a) is the chemical shift of-Si-CH 3 hydrogen between 0 and 0.4ppm, (b) 1.4ppm, (c) 1.6 to 1.7ppm, (D) 2.4ppm, (e) 3.5ppm, (f) 3.7ppm, (f) 4.1ppm (g) are all-CH in AGE, PC L and PTMG₂Chemical shift of the hydrogen in, disappearance of the chemical shift of the hydrogen on the vinyl group at around 6 ppmD4vi and AGE have been added. By using¹The result of H-NMR characterization shows that a four-arm polymer (D4 vi-AGE-PTMG-PC L) with cyclosiloxane dendritic nodes, polytetrahydrofuran as a soft block and polycaprolactone as a compatibilization block has been synthesized.

FIG. 2 is a graph of the shape memory of P L A by a four-armed polymer prepared according to the present invention.

Detailed Description

The present invention will be specifically described below by way of examples.

Example 1:

weighing azodiisobutyronitrile into an ampoule bottle provided with a magnetic stirring rod, vacuumizing, introducing nitrogen, adding a certain amount of D4vi and AGE through a syringe, taking tetrahydrofuran as a solvent, and placing the ampoule bottle in an oil bath at 80 ℃ for 12 hours. Then putting the obtained product and a proper amount of PTMG into a 250ml three-neck flask, introducing nitrogen to prevent high-temperature oxidation, heating after 40min to melt the PTMG, and stirring; slowly dripping catalyst concentrated sulfuric acid into a certain amount of tetrahydrofuran, uniformly mixing, then dripping into a reaction system, heating to 125 ℃, stopping introducing nitrogen, and vacuumizing for reaction. After 4h, 50ml of deionized water was added to the system to terminate the reaction, and the mixture was refluxed for 1h, then the catalyst was neutralized with Ca (OH)2 and subjected to liquid-separation water washing, and low-waste was removed by distillation under reduced pressure. Adding appropriate amount of the above product and toluene into a flame-dried ampoule equipped with a magnetic stirring rod, blowing nitrogen gas, adding caprolactone monomer, and stirring at 65 deg.C for 45 min. Adding a catalyst stannous octoate toluene solution into a bottle through a syringe, and heating to 120 ℃ for reaction for 24 hours. The product was precipitated with petroleum ether and dried under vacuum at 40 ℃ for 12 h.

P LL A, D₄ ^viAdding the-AGE-PTMG-PC L into a trichloromethane solvent according to the mass ratio of 1:1, wherein the total mass of the P LL A, D4vi-AGE-PTMG-PC L is 29 percent of the total mass of the solute and the solvent, stirring overnight at room temperature, pouring the solution stirred overnight onto a glass plate, allowing the solution to freely flow and cast on the glass plate, naturally volatilizing for two days at normal temperature (about 20 ℃) and normal pressure, curing the film in air, and then vacuumizing and drying at 25 ℃ for later use.

The pure P L A film (A) and the composite film (B) are respectively heated to 50 ℃ for deformation, then cooled to room temperature for shaping, and then heated to 50 ℃ for recovery, the pure P L A is difficult to process and deform at 50 ℃ and has no obvious recovery effect, while the composite film is easy to process and deform under the condition, and the sample is heated again at 50 ℃ for recovery of the original shape.

Claims

1. A quadriarm polymer for endowing P L A shape memory, which is a block polymer, wherein the molecular arm contains PTMG soft block and PC L compatibilization block, and the molecular structure is as follows by taking cyclosiloxane as the center:

the molecular center structure precursor of the four-arm polymer for endowing the P L A shape memory is as follows:

the structure of the PC L compatibilized block on the molecular arm of the four-arm polymer for endowing the P L A shape memory is as follows:

y is an integer greater than 1 and is,

the PTMG soft block structure on the molecular arm of the four-arm polymer for endowing the P L A shape memory is as follows:

x is an integer greater than 1.