Development of Biodegradable Engineering Plastics

生物降解工程塑料的发展

• 批准号: 12650868
• 负责人: MIYAMOTO Masatoshi
• 金额: $ 2.24万
• 依托单位: Kyoto Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650868/
• 关键词: cyclic dipeptide; biodegradable aliphatic polyeste; aspartic acid; Lipase PS; enzymatic hydrolysis; tensile strength and elongation; cyclic diketopiperazine; グルタミン酸; リシン; 生分解性ポリエステル; ジペプチド環; アスパラギン酸環状2量体; 重縮合

Biodegradable ahphatic polyesters are used for both biomedical and general purposes. However, their mechanical and thermal properties are insufficient in comparison with aromatic polyesters. It is well known that the introduction of rigid rings into the polymer backbone improves both thermal and mechanical properties, although small aromatic compounds produced by the hydrolysis of such a material can be harmful. Therefore, to improve thermal properties of ahphatic polyesters, dimethyl 3, 6-diketopiperazine-2, 5-diacetate (DDK), which has a rigid 6-membered ring, was synthesized from aspartic acid and used as the dicarboxylic acid component for aliphatic polyesters.First, a homopolymer (P(DDK-TEG)) was prepared from DDK and tetraethylene glycol (TEG). The molecular weight of P(DDK-TEG) was low because of the low solubility of DDK as well as the low thermal stability of the resulting homopolymer.Next, DDK was introduced to PBS by the copolycondensation with dimethyl succinate and 1, 4-butanediol. The products were soluble in chloroform as far as their DDK content did not exceed 10 mol%. The copolymer showed improved thermal stability: its 5% weight loss temperature was found to be 341℃ under nitrogen, while that of PBS was 307℃. The introduction of the rigid unit into the copolymer backbone reduces the mobility of the chain above the melting point, which is considered to retard its thermal decomposition. A film was prepared from a copolymer, whose DDK content was 6.8 mol% and Mw was 100, 000. This sample was successfully hydrolyzed by Lipase PS^【○R】, although the degradation rate was lower than that of PBS. The non-enzymatic degradation of the copolymer proceeded much faster than that of PBS did, which is explained by the highly polar nature of the DDK unit: it is so hydrophilic that it assists the penetration of water into the sample which results in the acceleration of non-enzymatic hydrolysis.

可生物降解的脂肪族聚酯用于生物医学和一般目的。然而，与芳族聚酯相比，它们的机械和热性能不足。众所周知，在聚合物主链中引入刚性环可以改善热性能和机械性能，尽管这种材料水解产生的小芳香族化合物可能是有害的。因此，为了改善脂肪族聚酯的热性能，以天冬氨酸为原料合成了具有刚性六元环的3，6-二酮哌嗪-2，5-二乙酸二甲酯（DDK），并将其作为脂肪族聚酯的二元羧酸组分。由于DDK的溶解度低，所得均聚物的热稳定性差，导致P（DDK-TEG）的分子量较低。只要DDK含量不超过10mol%，产物可溶于氯仿。该共聚物具有较好的热稳定性，在氮气保护下其5%失重温度为341℃，而PBS为307℃。将刚性单元引入到共聚物主链中降低了链在熔点以上的移动性，这被认为是延迟其热分解。由DDK含量为6.8摩尔%且Mw为100，000的共聚物制备膜。该样品被脂肪酶PS^[○R]成功水解，尽管降解速率低于PBS。共聚物的非酶降解比PBS的非酶降解进行得快得多，这是由DDK单元的高极性性质解释的：它是如此亲水，以至于它有助于水渗透到样品中，这导致非酶水解的加速。