Studies on Structure and Physical Properties of Poly (lactic acid)-Based Biodegradable Polyesters

本研究的目的是(1)开发表面改性(碱处理、可生物降解聚合物涂层)、共混(亲水性可生物降解聚合物、对映体和无机粒子)以及相分离成孔等新方法，以控制聚丙交酯S[聚乳酸S(PLAS)]基可生物降解聚酯的物理性能和生物降解性；(2)研究所制备材料的生物降解机理；(3)开发一种利用高温高压水将PLA回收为单体的新方法。结果表明，对于包括聚乳酸在内的可生物降解聚酯，表面改性可有效地加速和减速其生物降解而不侵蚀材料的核心部分，共混物在相分离时倾向于加速其生物降解，而孔的形成对于制备软材料和加速其生物降解是有效的。此外，球晶内晶区之间的“限制无定形区域”比球晶外的“自由无定形区域”具有更强的抗水解性，用高温高压水在熔体中进行水解是回收聚L-丙交酯[聚L-乳酸]为L-乳酸的有效方法。

The purposes of this study were(1)to develop new methods such as surface modification (alkaline treatment, biodegradable polymer coating), blending (hydrophilic biodegradable polymers, enantiomeric PLAs, and inorganic particles), and pore formation by the use of phase separation, to control physical properties and biodegradability of the poly (lactide) s [poly (lactic acid) s (PLAs)]-based biodegradable polyesters,(2)to investigate biodegradation mechanisms of the prepared materials, and(3)to develop a novel method for recycling PLAs to their monomers by the use of high-temperature and high-pressure water. It was found for biodegradable polyesters including PLAs that surface modification is effective both for acceleration and deceleration of their biodegradation without erosion of the core part of the materials, that blending is inclined to accelerate their biodegradation when the blends are phase-separated, and that pore formation is effective both for preparation of soft materials and acceleration of their biodegradation. Moreover, "restricted amorphous region" between the crystalline regions in spherulites was found to be much more hydrolysis-resistant than "free amorphous regions" outside spherulites and hydrolysis in the melt by the use of high-temperature and high-pressure water was shown to be a powerful method to recycling poly (L-lactide) [poly (L-lactic acid)] to L-lacticacid.