Influence of conformational asymmetry on polymer-polymer interactions: An entropic or enthalpic effect?

Kristoffer Almdal, Marc A. Hillmyer, Frank S. Bates

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

The order-to-disorder transition (ODT) of 21 compositionally symmetric diblock copolymers consisting of various combinations of poly(ethylene) (PE), poly(ethyl ethylene) (PEE), poly(ethylene-propylene) (PEP), poly(ethylene oxide) (PEO), and poly(dimethylsiloxane) (PDMS) was used as a measure of the strength of the interaction between the polymers. Conformational asymmetry makes a contribution to polymer-polymer thermodynamics that is not explainable within existing simple theories. For a series of PDMS-hydrocarbon diblock copolymers the observed phase behavior can be rationalized through a self-consistent set of solubility parameters. However, this model as well as other models breaks down when the phase behavior of a series of PEO-hydrocarbon block copolymers is included. We suggest that conformational asymmetry leads to an enthalpic contribution to the Flory-Huggins parameter χ through an effective coordination number which is maximized when both of the blocks have large conformational symmetry parameters, β2.

Original languageEnglish (US)
Pages (from-to)7685-7691
Number of pages7
JournalMacromolecules
Volume35
Issue number20
DOIs
StatePublished - Sep 24 2002

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