Biologically Safe Poly(L-lactic acid) Blends with Tunable Degradation Rate: Microstructure, Degradation Mechanism, and Mechanical Properties
Biologically Safe Poly(L-lactic acid) Blends with Tunable Degradation Rate: Microstructure, Degradation Mechanism, and Mechanical Properties
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DOI：
10.1021/acs.biomac.7b00016
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发表时间：
2017-04-01
影响因子：
6.2
通讯作者：
Ogawa, Ryohei
中科院分区：
文献类型：
--
作者：
Oyama, Hideko T.;Tanishima, Daisuke;Ogawa, Ryohei
虽然聚（L-乳酸）（PLLA）被认为是在人体内可生物降解的，但其疏水性使其持续约10分钟。5.5年这项研究表明，生物安全的丙交酯共聚物，聚（天冬氨酸-共-L-丙交酯）（PAL）和聚（苹果酸-共-L-丙交酯）（PML），分散在PLLA功能作为雷管（触发器），其在生理条件下的水解降解。共聚物显著增强水解，因此，PLLA的降解速率变得容易通过控制PAL和PML的量来调节。本研究阐明了单轴拉伸对PLLA共混膜的结构发展，力学性能和生理条件下的水解降解的影响。在初始降解阶段，单轴拉伸对质量损失没有影响;然而，在后期降解阶段，不太发达的晶体以及无定形链在低拉伸比（DR）下可降解，然而，不仅高度发达的晶体，而且取向的无定形链在高DR下对水解变得不敏感。我们的工作提供了重要的分子水平结果，表明可生物降解材料可以具有极好的机械性能，并且在生理条件下也在所需的时间内消失。
Although poly(L-lactic acid) (PLLA) is reputed to be biodegradable in the human body, its hydrophobic nature lets it persist for ca. 5.5 years. This study demonstrates that biologically safe lactide copolymers, poly(aspartic acid-co-L-lactide) (PAL) and poly(malic acid-co-L-lactide) (PML), dispersed in the PLLA function as detonators (triggers) for its hydrolytic degradation under physiological conditions. The copolymers significantly enhance hydrolysis, and consequently, the degradation rate of PLLA becomes easily tunable by controlling the amounts of PAL and PML. The present study elucidates the effects of uniaxial drawing on the structural development, mechanical properties, and hydrolytic degradation under physiological conditions of PLLA blend films. At initial degradation stages, the mass loss was not affected by uniaxial drawing; however, at late degradation stages, less developed crystals as well as amorphous chains were degradable at low draw ratio (DR), whereas not only highly developed crystals but also the oriented amorphous chains became insensitive to hydrolysis at high DR. Our work provides important molecular level results that demonstrate that biodegradable materials can have superb mechanical properties and also disappear in a required time under physiological conditions.