Hans Marc, Keul Helmut, Moeller Martin
DWI an der RWTH Aachen e.V. and Institute of Technical and Macromolecular Chemistry, RWTH Aachen, Pauwelsstr. 8, D-52056 Aachen, Germany.
Biomacromolecules. 2008 Oct;9(10):2954-62. doi: 10.1021/bm8007499. Epub 2008 Sep 20.
When a linear or a four arm star-shaped polyglycidol is used as macroinitiator, densely grafted poly(glycidol-graft-epsilon-caprolactone) and poly(glycidol-graft-L-lactide) and loosely grafted poly[(glycidol-graft-epsilon-caprolactone)-co-glycidol] copolymers have been synthesized by chemical or, in the latter case, by enzymatic catalyzed ring-opening polymerization of epsilon-caprolactone and L-lactide. The well-defined copolymers possess similar molecular weights, but differ in their architecture, microstructure and chemical composition. The hydrolytic degradation behavior was studied in a phosphate buffer solution at pH 7.4 and 37 degrees C for up to 90 days. After different time periods, the mass loss was determined and the degraded copolymers were analyzed by means of NMR, size exclusion chromatography, and scanning electron microscopy. Compared to linear poly(epsilon-caprolactone), poly[(glycidol-graft-epsilon-caprolactone)-co-glycidol] shows a change of the degradation mechanism and a tremendous enhancement of polymer degradation. As this effect is attributed to the high concentration of hydroxy groups at the polyglycidol backbone, this work points out a new possibility to tailor the degradation profiles of polyesters by the introduction of functionality into the polymeric material.
当使用线性或四臂星形聚缩水甘油作为大分子引发剂时，通过ε-己内酯和L-丙交酯的化学开环聚合（后一种情况为酶催化开环聚合），已合成了高密度接枝的聚（缩水甘油-接枝-ε-己内酯）和聚（缩水甘油-接枝-L-丙交酯）以及低密度接枝的聚[（缩水甘油-接枝-ε-己内酯）-共-缩水甘油]共聚物。这些结构明确的共聚物具有相似的分子量，但在结构、微观结构和化学组成上有所不同。在pH 7.4、37℃的磷酸盐缓冲溶液中研究了它们的水解降解行为，长达90天。在不同时间段后，测定质量损失，并通过核磁共振、尺寸排阻色谱和扫描电子显微镜对降解的共聚物进行分析。与线性聚（ε-己内酯）相比，聚[（缩水甘油-接枝-ε-己内酯）-共-缩水甘油]显示出降解机制的改变和聚合物降解的显著增强。由于这种效应归因于聚缩水甘油主链上高浓度的羟基，这项工作指出了通过在聚合物材料中引入官能团来定制聚酯降解曲线的新可能性。
