Dewetting inhibition and interfacial structures of silsesquioxane- terminated polystyrene thin films

Abstract

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 de wetting 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. © 2007 The Society of Polymer Science.