Shape memory and nanostructure in poly(norbornyl-POSS) copolymers

The microstructure and shape-memory properties of norbornyl-POSS hybrid cop olymers having either cyclohexyl corner groups (CyPOSS) or cyclopentyl corn er groups (CpPOSS) were investigated by transmission electron microscopy an d thermomechanical analysis. Here, BOSS refers to the polyhedral oligomeric silsesquioxane macromer. Samples containing 50wt% of BOSS macromer have be en mechanically drawn at temperatures above their glass transition temperat ures, followed by rapid quenching in LN2 Shape-memory properties of such dr awn samples were explored by measuring recovered strain while heating above the T-g using thermomechanical analysis. Incorporation of BOSS comonomers within PN is found to slightly reduce the percentage recovery, while improv ing thermal stability significantly, Interestingly, the types of corner gro ups in the BOSS macromer affect the shape-memory behaviour, with the CyPOSS copolymer showing lower percentage recovery than the CpPOSS copolymer due to enhanced aggregation of CyPOSS macromers. (C) 2000 Society of Chemical I ndustry.