Glass transition dynamics and surface layer mobility in unentangled polystyrene films

Zhaohui Yang, Yoshihisa Fujii, Fuk Kay Lee, Chi Hang Lam, Ophelia K.C. Tsui

Research output: Journal article publicationJournal articleAcademic researchpeer-review

425 Citations (Scopus)


Most polymers solidify into a glassy amorphous state, accompanied by a rapid increase in the viscosity when cooled below the glass transition temperature (Tg). There is an ongoing debate on whether the Tgchanges with decreasing polymer film thickness and on the origin of the changes. We measured the viscosity of unentangled, short-chain polystyrene films on silicon at different temperatures and found that the transition temperature for the viscosity decreases with decreasing film thickness, consistent with the changes in the Tgof the films observed before. By applying the hydrodynamic equations to the films, the data can be explained by the presence of a highly mobile surface liquid layer, which follows an Arrhenius dynamic and is able to dominate the flow in the thinnest films studied.
Original languageEnglish
Pages (from-to)1676-1679
Number of pages4
Issue number5986
Publication statusPublished - 25 Jun 2010

ASJC Scopus subject areas

  • General


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