Direct Observation of Micelle Fragmentation via In Situ Liquid-Phase Transmission Electron Microscopy,ACS Macro Letters

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Direct Observation of Micelle Fragmentation via In Situ Liquid-Phase Transmission Electron Microscopy
ACS Macro Letters ( IF 5.1 ) Pub Date : 2020-05-06 , DOI: 10.1021/acsmacrolett.0c00273
Julia T Early , Kevin G Yager ₁ , Timothy P Lodge

Affiliation

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 °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.

中文翻译：

通过原位液相透射电子显微镜直接观察胶束断裂

最近，人们的注意力集中在了解嵌段共聚物胶束的动力学和弛豫动力学，包括胶束断裂和融合等机制。先前关于嵌段共聚物胶束断裂的少数研究依赖于整体平均技术，例如小角 X 射线散射和动态光散射；一些单独的粒子通过非原位透射电子显微镜成像。在这里，我们报告了对三种分子量的 1,2-聚丁二烯嵌段的碎裂的直接观察。-使用高温液相透射电子显微镜（LP-TEM）在离子液体1-乙基-3-甲基咪唑鎓双（三氟甲基磺酰基）亚胺中的聚（环氧乙烷）（PB-PEO）胶束。原位 LP-TEM 的使用为嵌段共聚物胶束在碎裂过程中的演变提供了独特的见解。具体来说，在加热到 170 °C 时，观察到从球形胶束到长椭圆体的一系列形态转变，然后是“花生”形状，然后是双球室胶束，其中最后一个被认为是过渡状态。

更新日期：2020-05-06

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