Dispersion morphology of poly(methyl acrylate)/silica nanocomposites

Dustin W Janes, Joseph F. Moll, Shane E. Harton, Christopher J. Durning

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Nearly monodisperse poly(methyl acrylate) (PMA) and spherical SiO 2 nanoparticles (NP, d = 14 ± 4 nm) were co-cast from 2-butanone, a mutually good solvent and a displacer of adsorbed PMA from silica. The effects of NP content and post-casting sample history on the dispersion morphology were found by small-angle X-ray scattering supplemented by transmission electron microscopy. Analysis of the X-ray results show that cast and thermally annealed samples exhibited a nearly random particle dispersion. That the same samples, prior to annealing, were not well-dispersed is indicative of thermodynamic miscibility during thermal annealing over the range of NP loadings studied. A simple mean-field thermodynamic model suggests that miscibility results primarily from favorable polymer segment/NP surface interactions. The model also indicates, and experiments confirm, that subsequent exposure of the composites to the likely displacer ethyl acetate results in entropic destabilization and demixing into NP-rich and NP-lean phases.

Original languageEnglish (US)
Pages (from-to)4920-4927
Number of pages8
JournalMacromolecules
Volume44
Issue number12
DOIs
StatePublished - Jun 28 2011

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