Ultrathin polymer films, glass transition effects

DeMaggio, W.E. Frieze, D.W. Gidley, M. Zhu, H.A. Hristov, and A.F. Yee, Interface and surface effects on the glass transition in thin polystyrene films, Phys. Rev. Lett. 78, 1524 (1997). " D.B. Hall, J.C. Hooker, and J.M. Torkelson, Ultrathin polymer films near the glass transition Effect on the distribution of a relaxation times as measured by second harmonic generation, Macro molecules 30, 667 (1997). 

Hall DB, Hooker JC, Torkelson JM (1997) Ultrathin polymer films near the glass transition effect on the distribution of alpha-relaxation times as measured by second harmonic generation. Macromolecules 30 667-669... 

Ellison CJ, Kim SD, Hall DB, Torkelson JM (2002) Confinement and processing effects on glass transition temperature and physical aging in ultrathin polymer films novel fluorescence measurements. Eur Phys J E 8 155-166... 

Priestley RD, Broadbelt LJ, Torkelson JM (2005) Physical aging of ultrathin polymer films above and below the bulk glass transition temperature effects of attractive vs neutral polymersubstrate interactions measured by fluorescence. Macromolecules 38 654—657... 

Tremendous interest has arisen in recent years regarding die issues of chain mobility and glass transition at polymer surfaces (1-4). Keddie et al used ellipsometric measurements of thermal expansivity to study Tg of polystyrene on silicon as a function of film thickness (1). The observed Tg asymptotically approached the bulk value of 100 C as thickness was increased, but for thinner films lO s of nm), Tg was significantly depressed. Clearly, such effects are of critical importance in the application of ultrathin polymer films as lubricants and protective coatings in magnetic data storage devices and micromechanical systems (5). Until recently, however, direct mechanical measurements of polymer behavior at the nanoscopic scale (which is necessary for mechanical analysis of ultrathin films) and at elevated temperatures has not been possible. 

Serghei, A., Tress, M., Kremer, F. Confinement effects on the relaxation time distribution of the dynamic glass transition in ultrathin polymer films. Macromolecules 39, 9385 (2006)... 

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