Formation mechanisms of higher order structures of simultaneously polymerized methacrylate/urethane polymer blends

Abstract

Poly(methyl methacrylate) (PMMA) is a material with a high modulus of elasticity and good processability. However, it is also known for its brittleness. A previous paper reported on the toughening mechanisms of a polymethacrylate/polyurethane blend using simultaneous polymerization. The polymer blend has a 100 nm phase separation structure and spherulites of several micrometers in size. As a result, the polymer blend was toughened due to the occurrence of multiple crazes and shear yielding in the matrix polymer. This paper investigates the mechanisms behind the formation of higher order structures by observing the formation process of 100 nm phases and spherulites. The 100 nm phase was formed during the simultaneous polymerization of methacrylate monomer and urethane prepolymer. While the small crystalline nuclei were formed during heating at the temperature of the glassy region for the polymethacrylate matrix, then the small crystalline nuclei grew into spherulites with sizes of several micrometers when heated at the glass transition temperature of the matrix polymer.