Direct observation of critical Casimir effect using capacitance measurements for thin polymer films

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The purpose of the present study was to elucidate the existence of Casimir force for thin films of polymer blends with a critical component. We made precise measurements of electric capacitance at 100kHz for thin films of poly(dimethyl siloxane)/poly(ethyl methyl siloxane) with 55 % wt fraction of PEMS. The electric capacitance decreases with increasing temperature above the glass transition temperature and then shows a plateau around the critical temperatures. This results suggest that there is an attractive interaction between two electrodes. The origin of the attractive force might be due to the Casimir forces, although the detailed measurements could not yet be done successfully. Secondly, we measured the dynamics of alpha-process of poly(2-chlorostyrene) thin films between two polystyrene thin films with various thicknesses using dielectric spectroscopy for annealing process. This experiment will be important for understanding of the microscopic mechanism of the Casimir effect.