Surface Morphology of Polyphenylsilsesquioxanes/Hydroxyl-Functionalized Polystyrene Blends Investigated by Atomic Force Microscopy

Phase separation morphology in the thin blend film of polyphenylsilsesquioxane (PPSQ) and hydroxyl-functionalized polystyrene (PSOH) was investigated. PSOH was synthesized by anionic polymerization and identified with TLC. 1H NMR, and GPC. The two polymers were dissolved in a common solvent and the thin film was prepared by spincoating. Atomic force microscopy (AFM) has been used to investigate the surface morphology of the thin blend films. In 20% PPSQ and 80% PSOH blends, the PPSQ-rich phase was uniformly dispersed like granules and domain size was as small as 100nm. Comparing it with the PPSQ/PS blend with the same content of PPSQ, the domain size is about one third of that of the PPSQ/PS blend. This enhanced miscibility is believed to result from intermolecular hydrogen bonding between the PPSQ phase and the PSOH phase, which was verified by IR investigation. However, the PPSQ/PSOH (80/20) blend showed morphology of the so large domain distributed irregularly. The size of dispersed phase ranged from 500 nm to 1500 nm.