Direct Observation of Micelle Fragmentation via In Situ Liquid-Phase Transmission Electron Microscopy
Direct Observation of Micelle Fragmentation via In Situ Liquid-Phase Transmission Electron Microscopy
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DOI：
10.1021/acsmacrolett.0c00273
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发表时间：
2020-05-19
影响因子：
7.015
通讯作者：
Lodge, Timothy P.
中科院分区：
文献类型：
--
作者：
Early, Julia T.;Yager, Kevin G.;Lodge, Timothy P.
最近，人们关注于了解嵌段共聚胶束的动力学和松弛动力学，包括胶束破碎和融合的机理。以往对嵌段共聚聚合物胶束碎裂的研究主要依靠小角X射线散射和动态光散射等系综平均技术，并用非原位电子显微镜对个别粒子进行了成像。本文报道了1，2-聚丁二烯嵌段聚氧乙烯(PB-PEO)胶束在离子液体1-乙基-3-甲基咪唑双(三氟甲基磺酰亚胺)离子液体中三种相对分子质量胶束裂解的直接观察。原位LP-TEM的使用为嵌段共聚聚合物胶束在裂解过程中的演变提供了独特的见解。具体地说，加热到170摄氏度时，观察到一系列形态转变，从球形胶束到长椭球，然后是花生形状，然后是两个球形隔室的胶束，其中最后一个被认为是过渡态。
Recently, attention has been directed toward understanding the dynamics and relaxation kinetics of block copolymer micelles, including mechanisms such as micelle fragmentation and fusion. The few prior studies on block copolymer micelle fragmentation relied on ensemble averaging techniques such as small-angle X-ray scattering and dynamic light scattering; some individual particles were imaged by ex situ transmission electron microscopy. Here we report the direct observation of fragmentation for three molecular weights of 1,2-polybutadiene-block-poly(ethylene oxide) (PB-PEO) micelles in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide using high-temperature liquid-phase transmission electron microscopy (LP-TEM). The use of in situ LP-TEM provides unique insights into the evolution of block copolymer micelles during fragmentation. Specifically, upon heating to 170 degrees C, a sequence of morphological transitions from a spherical micelle to a prolate ellipsoid, then a "peanut" shape, followed by a two-spherical-compartment micelle was observed, where the last is presumed to be the transition state.