Time-resolved specular and off-specular neutron reflectivity measurementson deuterated polystyrene and poly(vinyl methyl ether) blend thinfilms during dewetting process

摘要

We performed time-resolved specular and off-specular neutron reflectivity measurements on blendthin films 42 and 98 nm thick of deuterated polystyrene and poly(vinyl methyl ether) duringdewetting process induced by the phase separation in two phase region using a time-of-flightneutron reflectometer. In the specular measurements we found that the phase separation directed tothe depth direction occurred near the air interface as well as near the Si substrate during theincubation period before dewetting. In addition we also found that the phase separation occurredasymmetrically at the two interfaces and inhomogeneously in the film plane, showing that thedewetting was induced by the composition fluctuation mechanism. Off-specular reflectivity wasanalyzed, for the first time, to evaluate kinetics of structure formation in the film plane during thedewetting process. We found in the analysis that the droplets formation in micrometer scale occurredin the late stage of dewetting.