Premade versus in situ formed compatibilizer at the PS/PMMA interface: contribution of the Raman confocal microscopy to the fracture analysis

The interface of a two-layer assembly of polystyrene (PS) and poly(methyl m ethacrylate) (PMMA) was modified by an intermediate layer of either a prema de poly(styrene-g-methyl methacrylate) copolymer (P(S-g-MMA)) or a preblend of mutually reactive PS and PMMA synthesized by atom transfer radical poly merization (ATRP). No significant difference was found in the interfacial f racture toughness measured by the double cantilever beam test, although the morphology of the interfacial region was not the same when observed by tra nsmission electron microscopy. The premade copolymer formed a distinct inte rphase, in contrast to the sharp interface that was observed in the case of the reactive system. The analysis of the fracture surfaces by Raman confoc al microscopy showed that the fracture occurred alternatively in the PS pha se and either at the PS/copolymer interface for the non reactive system or at the PS/PMMA interface for the reactive one. (C) 2001 Elsevier Science Lt d. All rights reserved.