Direct Observation of Micelle Fragmentation via in Situ Liquid-Phase Transmission Electron Microscopy

Julia T. Early, Kevin G. Yager, Timothy P. Lodge

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)756-761
Number of pages6
JournalACS Macro Letters
Volume9
Issue number5
DOIs
StatePublished - May 19 2020

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© 2020 American Chemical Society.

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