Dielectric and ellipsometric studies of the dynamics in thin films of isotactic poly(methylmethacrylate) with one free surface

摘要: We have performed dielectric loss measurements at 1 kHz on thin films of isotactic poly(methyl methacrylate). A key distinction our studies is that the samples measured were supported with one free surface rather than metallic electrodes covering both surfaces. This unique sample geometry allows us to eliminate any effects due evaporation metal onto top film and provides a opportunity make direct comparisons between glass transition measurements. Film thicknesses in range from 6 microm 7 nm prepared Al coated substrates. The peak ellipsometric temperature all measured. was found exhibit no discernible thickness dependence either maximum value or shape curve. In contrast, T(g) values decrease decreasing shift 10 K for 7-nm film. Dielectric also made these showed peak. Finally, Si These exhibited an increasing increase approximately 15 being