School of Chemistry, University of Bristol , Bristol BS8 1TS, United Kingdom.
School of Physics, University of Bristol , Bristol BS8 1TS, United Kingdom.
J Am Chem Soc. 2016 Mar 30;138(12):4087-95. doi: 10.1021/jacs.5b12735. Epub 2016 Mar 22.
Self-assembled "cross" architectures are well-known in biological systems (as illustrated by chromosomes, for example); however, comparable synthetic structures are extremely rare. Herein we report an in depth study of the hierarchical assembly of the amphiphilic cylindrical P-H-P triblock comicelles with polar (P) coronal ends and a hydrophobic (H) central periphery in a selective solvent for the terminal segments which allows access to "cross" supermicelles under certain conditions. Well-defined P-H-P triblock comicelles M(PFS-b-PtBA)-b-M(PFS-b-PDMS)-b-M(PFS-b-PtBA) (M = micelle segment, PFS = polyferrocenyldimethylsilane, PtBA = poly(tert-butyl acrylate), and PDMS = polydimethylsiloxane) were created by the living crystallization-driven self-assembly (CDSA) method. By manipulating two factors in the supermicelles, namely the H segment-solvent interfacial energy (through the central H segment length, L1) and coronal steric effects (via the PtBA corona chain length in the P segment, L2 related to the degree of polymerization DP2) the aggregation of the triblock comicelles could be finely tuned. This allowed a phase-diagram to be constructed that can be extended to other triblock comicelles with different coronas on the central or end segment where "cross" supermicelles were exclusively formed under predicted conditions. Laser scanning confocal microscopy (LSCM) analysis of dye-labeled "cross" supermicelles, and block "cross" supermicelles formed by addition of a different unimer to the arm termini, provided complementary characterization to transmission electron microscopy (TEM) and dynamic light scattering (DLS) and confirmed the existence of these "cross" supermicelles as kinetically stable, micron-size colloidally stable structures in solution.
自组装的“交叉”结构在生物系统中是众所周知的（例如，以染色体为例）；然而，可比的合成结构却极为罕见。本文深入研究了两亲性圆柱 P-H-P 三嵌段 comicelles 在选择性溶剂中按层次组装的情况，该溶剂对末端段具有亲性，可使具有极性（P）冠状端和疏水（H）中心外围的两亲性圆柱 P-H-P 三嵌段 comicelles 在某些条件下组装成“交叉”超分子。通过活的结晶驱动自组装（CDSA）方法，合成了具有明确结构的 P-H-P 三嵌段 comicelles M(PFS-b-PtBA)-b-M(PFS-b-PDMS)-b-M(PFS-b-PtBA)（M = 胶束段，PFS = 聚二茂铁基二甲基硅烷，PtBA = 聚（叔丁基丙烯酸酯），PDMS = 聚二甲基硅氧烷）。通过操纵超分子中的两个因素，即 H 段-溶剂界面能（通过中心 H 段长度 L1）和冠状位阻效应（通过 P 段中的 PtBA 冠状链长度 L2 与聚合度 DP2 相关），可以精细调节三嵌段 comicelles 的聚集。这使得可以构建一个相图，该相图可以扩展到其他具有不同中心或末端段冠状的三嵌段 comicelles，在预测条件下，“交叉”超分子将专门在这些条件下形成。通过对染料标记的“交叉”超分子的激光扫描共聚焦显微镜（LSCM）分析，以及通过向臂端添加不同的单体形成的嵌段“交叉”超分子，对透射电子显微镜（TEM）和动态光散射（DLS）进行了补充表征，并证实了这些“交叉”超分子的存在作为动力学稳定的、尺寸为微米级的胶体稳定结构存在于溶液中。
