Dewetting Inhibition and Interfacial Structures of Silsesquioxane-terminated Polystyrene Thin Films

Polyhedral oligomeric silsesquioxane (POSS)-terminated polystyrene (PS-POSS) was prepared by nitroxide-mediated radical polymerization of styrene with POSS-containing initiator, and the thermal stability of PS-POSS thin films was investigated. Rheological measurement of PS-POSS revealed that the rheological properties were profoundly affected by the presence of POSS end groups in low molecular weight region (Mn≍2000), while those were nearly unaffected in high molecular weight region (Mn≍40000). However, the introduction of POSS as a PS end group can actually stabilize PS thin films against dewetting in a range of the molecular weight used in this study. Neutron reflectivity measurement of deuterated PS-POSS thin film revealed that the POSS moieties of PS-POSS formed enrichment layer at the interfaces of the film. The segregation of the POSS end group at the film–substrate interface, which can modify the interface by tethering the PS chains at the interface, seems to be an important factor in the dewetting inhibition effect.

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