Temperature dependence of block copolymer thin films with different film thickness

Interfacial structure of a styrene-d8-2-vinylpyridine diblock copolymer thin films with lamellar microdomain was investigated by neutron reflectivity (NR) measurement at different temperatures above Tg of the component polymer. The thin film specimens with different film thicknesses were prepared by spin-coating method, and then annealed at 170°C in vacuum during more than one week before NR measurement. The observed specular reflectivity profiles exhibit several Bragg peaks up to high order, implying that the lamellar structure keeps highly-ordered state and preferential orientation along the direction parallel to the film surface even at high temperature above Tg. Further, it was found that the temperature dependence of lamellar domain spacing is different according the difference in total film thickness.