Viscosity and Surface-Promoted Slippage of Thin Polymer Films Supported by a Solid Substrate

Fei Chen, Dongdong Peng, Chi Hang Lam, Ophelia K.C. Tsui

Research output: Journal article publicationJournal articleAcademic researchpeer-review

27 Citations (Scopus)

Abstract

Thermally activated flow dynamics of polystyrene films supported by silicon is studied for a wide range of film thickness (h<sub>0</sub>) and molecular weights (M<sub>w</sub>). At low M<sub>w</sub>, the effective viscosity of the nanometer thin films is smaller than the bulk and decreases with decreasing h<sub>0</sub>. This is due to enhancement of the total shear flow by the augmented mobility at the free surface. As M<sub>w</sub> increases, with h<sub>0</sub> becoming smaller than the polymer radius of gyration (R<sub>g</sub>), the effective viscosity switches from being substrate-independent to substrate-dependent. We propose that interfacial slippage then dominates and leads to plug flow. The friction coefficient is found to increase with h<sub>0</sub> providing h<sub>0</sub>/R<sub>g</sub> < ∼1, demonstrating a surface-promoted confinement effect.
Original languageEnglish
Pages (from-to)5034-5039
Number of pages6
JournalMacromolecules
Volume48
Issue number14
DOIs
Publication statusPublished - 28 Jul 2015

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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