Surface properties and enzymatic degradation of end-capped poly(l-lactide)
Surface properties and enzymatic degradation of end-capped poly(l-lactide)
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DOI：
10.1016/j.polymdegradstab.2005.08.015
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发表时间：
2006-06
影响因子：
5.9
通讯作者：
K. Kurokawa;K. Yamashita;Y. Doi;H. Abe
中科院分区：
文献类型：
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作者：
K. Kurokawa;K. Yamashita;Y. Doi;H. Abe
采用推进接触角（θa）测量、石英晶体微天平（QCM）和原子力显微镜（AFM）研究了端部带有疏水十二烷基和十二烷基的聚l-丙交酯（PLLA）的表面性质和酶解过程。端盖型PLLA薄膜的θ值大于非端盖型PLLA薄膜的θ值，说明疏水性十二烷基和十二烷基在薄膜表面发生了分离。利用QCM技术监测了酶解过程中端盖PLLA薄膜在蛋白酶K存在下的重量变化。pla薄膜在降解的前几个小时失重较快，随后侵蚀速率下降。降解初期PLLA膜的侵蚀速率与分子链端结构有关，随疏水官能团数量的增加而减小。利用原子力显微镜对降解前后PLLA薄膜的表面形貌进行了表征。酶解后，无端盖PLLA膜表面瑕疵均匀。相反，端盖PLLA薄膜被酶降解为非均匀的，膜表面形成许多空洞。从这些结果可以得出结论，在PLLA分子链端引入疏水官能团可以抑制酶解初始阶段的侵蚀速率。
Surface properties and enzymatic degradation of poly(l-lactide) (PLLA) end-capped with hydrophobic dodecyl and dodecanoyl groups were investigated by means of advancing contact angle (θa) measurement, quartz crystal microbalance (QCM) and atomic force microscopy (AFM). The θavalues of end-capped PLLA films were larger than those of non-end-capped PLLA films, suggesting that the hydrophobic dodecyl and dodecanoyl groups were segregated on the film surface. The weight changes of end-capped PLLA thin films during enzymatic degradation in the presence of proteinase K were monitored by using a QCM technique. The relatively fast weight loss of PLLA film occurred during first few hours of degradation, followed by a decrease in the erosion rate. The erosion rate of PLLA films at the initial stage of degradation was dependent on the chain-end structure of PLLA molecules, and the value decreased with an increase in the amount of hydrophobic functional groups. The surface morphologies of PLLA thin films before and after degradation were characterized by AFM. After the enzymatic degradation, the surface of non-end-capped PLLA films was blemished homogeneously. In contrast, the end-capped PLLA thin films were degraded heterogeneously by the enzyme, and many hollows were formed on the film surface. From these results, it has been concluded that the introduction of hydrophobic functional groups at the chain-ends of PLLA molecules depressed the erosion rate at the initial stage of enzymatic degradation.