Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA.
J Am Chem Soc. 2013 Jul 31;135(30):10918-21. doi: 10.1021/ja4050532. Epub 2013 Jul 19.
We describe an approach to ordered nanoporous poly(lactide) that relies on self-assembly of poly(butadiene)-poly(lactide) (PB-PLA) diblock copolymers followed by selective degradation of PB using olefin metathesis. The block copolymers were obtained by a combination of anionic and ring-opening transesterification polymerizations. The molar mass of each block was tailored to target materials with either a lamellar or cylindrical microphase-separated morphology. Orientation of these nanoscale domains was induced in thin films and monolithic samples through solvent annealing and mechanical deformation, respectively. Selective degradation of PB was achieved by immersing the samples in a solution of Grubbs first-generation catalyst in cyclohexane, a nonsolvent for PLA. Successful elimination of PB was confirmed by size-exclusion chromatography and (1)H NMR spectroscopy. Direct imaging of the resulting nanoporous PLA was obtained by scanning electron microscopy.
我们描述了一种有序纳米多孔聚（乳酸）的方法，该方法依赖于聚丁二烯-聚（乳酸）（PB-PLA）嵌段共聚物的自组装，然后使用烯烃复分解选择性降解 PB。嵌段共聚物通过阴离子聚合和开环酯交换聚合的组合获得。每个嵌段的摩尔质量都经过精心设计，以获得层状或圆柱状微相分离形态的目标材料。通过溶剂退火和机械变形分别在薄膜和整体样品中诱导这些纳米级域的取向。通过将样品浸入环己烷中的 Grubbs 第一代催化剂溶液中，即 PLA 的不良溶剂中，实现了 PB 的选择性降解。通过尺寸排阻色谱法和 (1)H NMR 光谱法证实了 PB 的成功消除。通过扫描电子显微镜直接获得了所得纳米多孔 PLA 的图像。
