Compatibilization of model poly(styrene)/poly(dimethylsiloxane) blends

Pre-made block copolymer addition versus in situ reactive blending were compared as compatibilization routes for model poly(styrene) (PS)/poly(dimethylsiloxane) (PDMS) blends. Three different PS-b-PDMS diblock copolymers were added to a PS/PDMS (80/20) blend. An optimal block copolymer weight (16 kg/mol < M-u < 83 kg/mol) apparently allows sufficient copolymer diffusion to the interface to produce astable morphology. However, the PDMS domain size still remained relatively large (similar to 5 mu m). A blend of a monofunctional amine-terminated PS (PS-NH2) with a difunctional anhydride terminated PDMS (PDMS-(An)(2)) (80 wt.% PS phase) produced small, stable PDMS particles (similar to 0.3 mu m). These results suggest copolymers formed by reactive blending are more effective than pre-made blocks as a method to control PS/PDMS morphologies.