Mechanical properties and deformation mechanisms of poly(styrene-b-butylmethacrylate) diblock copolymers

The mechanical properties of poly(styrene-b-butylmethacrylate) diblock copolymers (PS-b-PBMA) with different lengths of polystyrene block were investigated. The copolymers display a composition range where the tensile strength of the block copolymers exceeds the values of the corresponding homopolymers. The mechanical properties of PS-b-PBMA diblock copolymers with lamellar structure are compared with bicontinuous and perforated lamellar structures. The investigation of the deformation mechanisms has shown that the craze structure and craze growth are strongly influenced by the microphase separated structures. The enhancement of mechanical properties of PS-b-PBMA diblock copolymers is discussed with respect to a possible correlation between phase behavior, morphology, deformation mechanisms and interface formation. (C) 1998 John Wiley & Sons, Ltd.