Effect of compatibilizer concentration and weight fraction on model immiscible blends with interfacial crosslinking

eactive compatibilization, in which a compatibilizer is formed by an interfacial coupling between wo reactive polymers, is commonly used when blending immiscible homopolymers. We consider eactive compatibilization using two multifunctional reactive polymers, which leads to a rosslinked copolymer at the interface. Experiments were conducted on model blends of olydimethylsiloxane PDMS and polyisoprene PI . Compatibilizer was formed by a chemical eaction between amine-functional PDMS and maleic anhydride-functional PI. Droplet-matrix lends with a PI:PDMS ratio of 30:70 or 70:30 and reactive compatibilizer loadings from 0.1% to % were examined by optical microscopy and rheometry. Experiments reveal that the effects of nterfacial crosslinking are highly asymmetric, with PI-continuous blends showing altogether ifferent behaviors from PDMS-continuous blends. The PI-continuous blends show unusual eatures including drop clusters and nonspherical drops. In contrast, PDMS-continuous blends isplayed a typical droplet-matrix morphology with round drops that do not appear to stick ogether. The rheological properties are also asymmetric: The PI-continuous blend showed gel-like ehavior in oscillatory experiments, high viscosity, and viscosity overshoots during startup of shear ow, whereas PDMS-continuous blends showed liquidlike behavior that is qualitatively similar to hat of compatibilizer-free blends. We speculate that the observed structural and rheological symmetry is attributable to the asymmetry of the compatibilizer architecture on the two sides of he interface. © 2011 The Society of Rheology. DOI: 10.1122/1.3571549