Decoupling bulk thermodynamics and wetting characteristics of block copolymer thin films

Sangwon Kim, Paul F. Nealey, Frank S. Bates

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

The consequences on certain physical properties of controlled levels of epoxidation of the poly(isoprene) blocks in poly(styrene-b-isoprene) (PS-PI) diblock copolymers and poly(isoprene) (hPI) homopolymers have been studied, where the products after epoxidation are denoted PS-PIxn and hPIxn, respectively. The effective interaction parameters χ eff between the PS and the PIxn blocks were estimated by applying mean-field theory to the lamellar periodicities identified by small-angle X-ray scattering and to the order-to-disorder transition temperatures determined by dynamic mechanical spectroscopy. These results were fit to a binary segment-segment interaction parameter model indicating a nonlinear change in χ eff with percent epoxidation. In contrast, contact angle measurement on hPIxn and lamellar orientations of thin-film PS-PIxn suggest that the surface energy of PIxn increases linearly with epoxidation. This decoupling of bulk and thin-film thermodynamic behaviors is attributed to the different roles that a random copolymer architecture plays in establishing three-dimensional order versus wetting at a two-dimensional surface.

Original languageEnglish (US)
Pages (from-to)11-14
Number of pages4
JournalACS Macro Letters
Volume1
Issue number1
DOIs
StatePublished - Aug 20 2012

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