Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, Royal Institute of Technology (KTH), S-100 44, Stockholm, Sweden.
Langmuir. 2010 Jan 5;26(1):378-83. doi: 10.1021/la902166j.
The effect of surface modification on the degradation process and degradation product patterns of degradable polymers is still a basically unexplored area even though a significant effect can be expected. Polylactide (PLA) and PLA grafted with acrylic acid (PLA-AA) were, thus, subjected to hydrolytic degradation, and water-soluble degradation products were determined by electrospray ionization-mass spectrometry (ESI-MS) after different time periods. Low molar mass compounds migrated from surface-grafted PLA already during the first 7 days at 37 degrees C, while it took 133 days in the case of nongrafted PLA before any low molar mass compounds were detected in the aging water. In addition, the degradation product pattern of surface-grafted PLA showed significant variation as a function of hydrolysis time with the evolution of short and long AA-grafted lactic acid oligomers as well as plain lactic acid oligomers after different time periods. The degradation product pattern of plain PLA consisted of lactic acid and its oligomers with up to 13 lactic acid units. Surface grafting, thus, changed the degradation product patterns and accelerated the formation of water-soluble degradation products.
尽管可以预期表面改性对可降解聚合物的降解过程和降解产物形态会产生重大影响，但目前这方面的研究仍基本处于空白。因此，对聚乳酸（PLA）和接枝丙烯酸的 PLA（PLA-AA）进行了水解降解，并用电喷雾电离质谱（ESI-MS）测定了不同时间后的水溶性降解产物。在 37°C 下，表面接枝 PLA 中的低摩尔质量化合物在最初的 7 天内就已经迁移出来，而非接枝 PLA 则需要 133 天才能在老化水中检测到低摩尔质量化合物。此外，随着水解时间的延长，表面接枝 PLA 的降解产物形态也发生了显著变化，不同时间后出现了短链和长链 AA 接枝乳酸低聚物以及纯乳酸低聚物。纯 PLA 的降解产物形态则由具有 13 个乳酸单元的乳酸及其低聚物组成。因此，表面接枝改变了降解产物形态并加速了水溶性降解产物的形成。
