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Viscosity and Surface-Promoted Slippage of Thin Polymer Films Supported by a Solid Substrate
Thermally activated flow dynamics of polystyrene films supported by silicon is studied for a wide range of film thickness (h0) and molecular weights (Mw). At low Mw, the effective viscosity of theExpand
Glass Transition Dynamics and Surface Layer Mobility in Unentangled Polystyrene Films
The viscosity of unentangled, short-chain polystyrene films on silicon at different temperatures is measured and it is found that the transition temperature for the Viscosity decreases with decreasing film thickness, consistent with the changes in the Tg of the films observed before. Expand
Affinity of Polystyrene Films to Hydrogen-Passivated Silicon and Its Relevance to the Tg of the Films
Qualitatively different thickness dependences have been observed in the glass transition temperature, Tg, of polystyrene (PS) films supported by hydrogen-passivated silicon (H−Si). It has beenExpand
Study of Elastic Modulus and Yield Strength of Polymer Thin Films Using Atomic Force Microscopy
Nanometer-scale elastic moduli and yield strengths of polycarbonate (PC) and polystyrene (PS) thin films were measured with atomic force microscopy (AFM) indentation measurements. By analysis of theExpand
Viscosity of PMMA on Silica: Epitome of Systems with Strong Polymer-Substrate Interactions
We measured the viscosity of poly(methyl methacrylate) (PMMA) films supported by silica, where the carbonyl group on the side chains of the polymer interacts strongly with the hydroxyl groups of theExpand
Effect of C60 molecular rotation on nanotribology.
The orientational order-disorder phase transition, in which the high temperature C60 free rotation is reduced to a low temperature hindered rotation, is shown to give rise to an abrupt change in friction and adhesion. Expand
Effect of Interfacial Interactions on the Glass Transition of Polymer Thin Films
Previous studies had demonstrated that the Tg of polymer thin films is strongly dependent on the interactions, γs, between the polymer and the underlying substrate. We present a study of the glassExpand
Effects of Chain Ends and Chain Entanglement on the Glass Transition Temperature of Polymer Thin Films
Monodispersed polystyrene with different molecular weights, Mw, from below the entanglement molecular weight, Me (∼20K Da), to well above was studied for effects of chain ends and chain entanglementExpand
Glass Transition Temperature of Polymer−Nanoparticle Composites: Effect of Polymer−Particle Interfacial Energy
Numerous studies have shown that the glass transition temperature, Tg, of polymers may change visibly upon addition of even small amounts of nanoparticles. In this study, we examine the effect ofExpand
Effects of Polymer Tacticity and Molecular Weight on the Glass Transition Temperature of Poly(methyl methacrylate) Films on Silica
The glass transition temperature (Tg) of poly(methyl methacrylate) (PMMA) films supported by silica was studied as a function of film thickness at two molecular weights (MW = 2.5 and ∼50 kg/mol) andExpand