A perspective on experimental findings and theoretical explanations of novel dynamics at free surface and in freestanding thin films of polystyrene
| Autor: | K. L. Ngai, Daniele Prevosto, Simone Capaccioli |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Materials science
sub-Rouse modes Nanotechnology 02 engineering and technology polystyrene 010402 general chemistry 01 natural sciences Viscoelasticity chemistry.chemical_compound free surface Thin film Composite material dynamics thin films Condensed Matter Physics chemistry.chemical_classification Relaxation (NMR) Polymer 021001 nanoscience & nanotechnology 0104 chemical sciences chemistry Creep Free surface Polystyrene 0210 nano-technology Glass transition |
| Popis: | Most studies of the dynamics at the surface and in thin films of polystyrene (PS) are focused on the change of glass transition temperature from the bulk value. In this perspective, we highlight three new developments in research on the dynamics of PS in high molecular weight (MW) freestanding PS thin films and at the surface of low MW PS. Novel findings from these developments require consideration of viscoelastic mechanisms with length scales longer than the segmental α-relaxation. The first development is the creep compliance measurements of high-MW PS thin films, probing not only the segmental α-relaxation, but also the polymer chain modes at higher compliance levels, including the sub-Rouse modes and the Rouse modes. The compliance data indicate the relaxation times of the sub-Rouse modes are reduced in thinner films like that of the segmental α-relaxation but to a much less extent. The second development is the novel observation of two glass transitions in freestanding polystyrene thin films by elli... |
| Databáze: | OpenAIRE |
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