Nanostructures and Mechanical Properties ofSelf-Assembled Epoxy / Block Copolymer Blends

Abstract

Regarding the network polymer blends prepared by mixing amphiphilic block copolymers with epoxy resins, the mechanisms of formation of nanostructures and the relationship between the phase structures and mechanical properties (fracture toughness, modulus of elasticity) were discussed. In specific, authors studied phenol novolac (PN) cured bisphenol A type epoxy resin (DGEBA) / polymethyl methacrylate - b - polybutyl acrylate - b - polymethyl methacrylate triblock copolymer (PMMA - b - PnBA - b - PMMA) blends. Periodical structures of 20－40 nanometer size existed from precuring stage, due to phase separation of incompatible PnBA component from DGEBA / PN matrix. Various nano-micelle structures such as spheres, cylinders, vesicles, lamellae, etc. were self-assembled in the network polymer blends after curing. On comparison in the same PnBA content, the fracture toughness of the epoxy polymer blend with cylindrical nanomicelle structure was the highest of these nanostructures, and the lamellar nano-micelle structure gave the lowest modulus of elasticity to the polymer blend. The sources generating these mechanical properties were clarified by microscopic observation.