Department of Materials Engineering, Graduate School of Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan.
J Am Chem Soc. 2013 Jan 30;135(4):1423-9. doi: 10.1021/ja3096587. Epub 2013 Jan 15.
Understanding the dynamic behavior of molecular self-assemblies with higher-dimensional structures remains a key challenge to obtaining well-controlled and monodispersed structures. Nonetheless, there exist few systems capable of realizing the mechanism of supramolecular polymerization at higher dimensions. Herein, we report the unique self-assembling behavior of polyion complexes (PICs) consisting of poly(ethylene glycol)-polyelectrolyte block copolymer as an example of two-dimensional supramolecular living polymerization. Monodispersed and submicrometer unilamellar PIC vesicles (nano-PICsomes) displayed time-dependent growth while maintaining a narrow size distribution and a unilamellar structure. Detailed analysis of the system revealed that vesicle growth proceeded through the consumption of unit PICs (uPICs) composed of a single polycation/polyanion pair and was able to restart upon the further addition of isolated uPICs. Interestingly, the resulting vesicles underwent dissociation into uPICs in response to mechanical stress. These results clearly frame the growth as a two-dimensional supramolecular living polymerization of uPICs.
理解具有更高维度结构的分子自组装的动态行为仍然是获得良好控制和单分散结构的关键挑战。尽管如此，能够实现超分子聚合机制的体系很少存在于更高维度。在这里，我们以聚电解质嵌段共聚物组成的聚（乙二醇）-聚电解质的聚离子复合物（PICs）为例，报道了二维超分子活性聚合的独特自组装行为。单分散的亚微米级单层 PIC 囊泡（纳米-PICosomes）显示出时间依赖性的生长，同时保持了窄的尺寸分布和单层结构。对该体系的详细分析表明，囊泡的生长是通过消耗由单个聚阳离子/聚阴离子对组成的单元 PIC（uPICs）进行的，并且能够在进一步加入分离的 uPICs 时重新开始。有趣的是，所得的囊泡在机械应力的作用下解离成 uPICs。这些结果清楚地表明，这种生长是 uPICs 的二维超分子活性聚合。
