Sun Liang, Pitto-Barry Anaïs, Kirby Nigel, Schiller Tara L, Sanchez Ana M, Dyson M Adam, Sloan Jeremy, Wilson Neil R, O'Reilly Rachel K, Dove Andrew P
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia.
Nat Commun. 2014 Dec 17;5:5746. doi: 10.1038/ncomms6746.
Co-crystallization of polymers with different configurations/tacticities provides access to materials with enhanced performance. The stereocomplexation of isotactic poly(L-lactide) and poly(D-lactide) has led to improved properties compared with each homochiral material. Herein, we report the preparation of stereocomplex micelles from a mixture of poly(L-lactide)-b-poly(acrylic acid) and poly(D-lactide)-b-poly(acrylic acid) diblock copolymers in water via crystallization-driven self-assembly. During the formation of these stereocomplex micelles, an unexpected morphological transition results in the formation of dense crystalline spherical micelles rather than cylinders. Furthermore, mixture of cylinders with opposite homochirality in either THF/H2O mixtures or in pure water at 65 °C leads to disassembly into stereocomplexed spherical micelles. Similarly, a transition is also observed in a related PEO-b-PLLA/PEO-b-PDLA system, demonstrating wider applicability. This new mechanism for morphological reorganization, through competitive crystallization and stereocomplexation and without the requirement for an external stimulus, allows for new opportunities in controlled release and delivery applications.
不同构型/立构规整度的聚合物共结晶可获得性能增强的材料。与每种纯手性材料相比，等规聚（L-丙交酯）和聚（D-丙交酯）的立体复合作用导致性能得到改善。在此，我们报道了通过结晶驱动的自组装，由聚（L-丙交酯）-b-聚（丙烯酸）和聚（D-丙交酯）-b-聚（丙烯酸）二嵌段共聚物的混合物在水中制备立体复合胶束。在这些立体复合胶束的形成过程中，意外的形态转变导致形成致密的结晶球形胶束而非圆柱形胶束。此外，在四氢呋喃/水混合物中或在65℃的纯水中，具有相反纯手性的圆柱形胶束混合物会分解成立体复合球形胶束。同样，在相关的聚环氧乙烷-b-聚L-丙交酯/聚环氧乙烷-b-聚D-丙交酯体系中也观察到转变，表明其具有更广泛的适用性。这种通过竞争性结晶和立体复合作用且无需外部刺激的形态重组新机制，为控释和递送应用带来了新机遇。
