Direct Visualization of Polymerization-Induced Self-Assembly of Amphiphilic Copolymers
Direct Visualization of Polymerization-Induced Self-Assembly of Amphiphilic Copolymers
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DOI：
10.1021/acs.macromol.2c02318
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发表时间：
2023-04
期刊：
影响因子：
5.5
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中科院分区：
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精确控制分子自组装的设计结构和性质的能力对于定制其功能的质量和功效是至关重要的，但控制从分子到自组装结构的演变的潜在机制尚未完全解决。在这里，我们采用了石墨烯液池（GLC）的透射电子显微镜（TEM）的方法来观察成核和聚合诱导自组装过程中的个别纳米胶束的演变。我们推测，电子束诱导自由基的形成，通过均裂的聚（甲基丙烯酸甘油酯）-硫代羰基硫（聚GMA-硫代羰基硫）大分子链转移剂（macroCTA），在此引发聚合的HPMA单体在水溶液中。疏水性嵌段PolyHPMA的链增长以及随后所得嵌段共聚物在溶液中的不稳定性触发了纳米级聚合物自组装体的形成。提出了聚合物组装体形成和演化的旋节线分解机制。这种原位可视化的聚合物胶束形成，没有金属离子标记，提供了新的见解理解的复杂机制的自组装过程中的两亲性分子。
The ability to have precise control over the designed structure and properties of molecular self-assemblies is critical for tailoring the quality and efficacy of their functionality, yet the underlying mechanisms governing the evolution from molecules into self-assembled structures are not fully resolved. Here, we employed the graphene liquid cell (GLC) transmission electron microscopy (TEM) approach to observe nucleation and evolution of individual nanoscale micelles during polymerization-induced self-assembly. We speculate that the electron beam induces radical formation by homolytic cleavage of the poly(glycerol methacrylate)–thiocarbonylthio (PolyGMA–thiocarbonylthio) macro-chain-transfer agent (macroCTA), at which it initiates the polymerization of HPMA monomer in aqueous solution. Chain growth of the hydrophobic block, PolyHPMA, and subsequent instability of the resulting block copolymer in the solution trigger the formation of the nanoscale polymer self-assemblies. The spinodal decomposing mechanism is proposed here for the formation and evolution of the polymer assemblies. Such in-situ visualization of polymeric micelle formation, devoid of metal-ion labeling, provides new insights into understanding the complex mechanism of the self-assembly process in amphiphilic molecules.