Impact of low-molecular mass components (oligomers) on the glass transition in thin films of poly(methyl methacrylate)

Matthew Dion, Andrew B. Larson, Bryan Vogt

Research output: Contribution to journalArticle

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Abstract

Commercial polydisperse atactic poly(methyl methacrylate) (PMMA) exhibits a decreased glass transition temperature (Tg) when the film thickness is less than ∼60 nm, whereas more model atactic PMMA shows an increased Tg in thin films supported on clean silicon wafers. NMR indicates no difference in tacticity, so the divergent thin film behavior appears related to the relative distribution of molecular mass. Extraction of some low molecular weight PMMA components from the commercial sample results in a significant modification of the thin film Tg compared with the initial PMMA fraction. The extracted sample exhibits initially a slight decrease in T g as the film thickness is reduced below ∼60 nm, but then T g appears to increase for films thinner than 20 nm. These results illustrate the sensitivity of polymer thin film properties to low-molecular mass components and could explain some of the contradictory reports on the T g of polymer thin films that exist in the literature.

Original languageEnglish (US)
Pages (from-to)2366-2370
Number of pages5
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume48
Issue number22
DOIs
Publication statusPublished - Nov 15 2010

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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