| 초록 |
Coherent x-rays available from the third generation synchrotron sources have opened many new avenues of research, e.g., measuring dynamics by X-ray photon correlation spectroscopy. I will present our recent findings of dynamics of block copolymer films by XPCS. The surface dynamics of poly[styrene-b-dimethylsiloxane] block copolymer films were investigated from well above to near the bulk glass transition temperature. Over-damped surface capillary wave relaxations on molten polymer films were determined by viscosity, surface tension, film thickness, and wave number. A universal scaling of the dynamics even with surface segregation was discovered over a wide range of total film thicknesses and temperatures. The viscosities from the segregation layer and the bottom are obtained from the comparison with the hydrodynamic theory for thermally excited fluctuations in viscous liquid. |
