1. Effects of Solvent Quality and Degree of Polymerizationon the Critical Micelle Temperature of Poly(ethylene oxide-b-n-butyl methacrylate) inIonic Liquids.
- Author
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Hoarfrost, Megan L. and Lodge, Timothy P.
- Subjects
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SOLVENTS , *POLYMERIZATION , *CRITICAL micelle concentration , *POLYETHYLENE oxide , *BUTYL methacrylate , *IONIC liquids - Abstract
Blockcopolymers are attractive building blocks for designing micelleshaving complex shapes and functionality, but experimental investigationsinto the detailed thermodynamics of block copolymer micellizationhave been constrained. In this work, we take advantage of the favorablesolvent properties of ionic liquids to study the thermodynamics ofblock copolymer micelle formation. Specifically, we investigate theeffects of solvent quality and degree of polymerization on the criticalmicelle temperature (cmt) of poly(ethylene oxide-b-n-butyl methacrylate) (PEO-b-PnBMA)in mixtures of two ionic liquids: 1-butyl-3-methylimidazolium:bis(trifluoromethylsulfonyl)imide([BMIm][TFSI]) and 1-ethyl-3-methylimidazolium:TFSI ([EMIm][TFSI]).The solvent quality for the core-forming block of the block copolymer,PnBMA, is varied over a wide range by blending the two ionic liquidsin different ratios, resulting in a large variation in the cmt ofPEO-b-PnBMA. It is shown that the interaction parameterbetween the solvent and PnBMA atthe cmt is approximatelyconstant for all of the ionic liquid mixtures. The enthalpies andentropies of micelle formation also do not vary with ionic liquidcomposition, suggesting that the nature of the polymer/solvent andsolvent/solvent interactions do not change much as the ionic liquidcomposition is varied despite the large change in solvent quality.Furthermore, the cmt is shown to depend on the degree of polymerizationof PnBMA as predicted by theory. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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