Nanostructuration effect on the mechanical properties of PMMA toughened by a triblock acrylate copolymer using multilayer coextrusion

Abstract

Multilayer coextrusion was used to obtain nanolayered films of self-assembled commercial triblock copolymer poly(methyl methacrylate-b-butyl acrylate-b-methyl methacrylate) (MAM) confined by poly (methyl methacrylate) (PMMA). A double level of organization is achieved: the obtained films are made of thousands of alternating continuous nanolayers of each component, while within the nanolayers, MAM is self-assembled with a cylindrical morphology. The mechanical properties of the resulting films were compared to those of virgin PMMA and to classically extruded PMMA/MAM blends with the same compositions where no control of the nanostructure can be achieved. It is shown that significant reinforcement can be obtained with the multilayer films compared to virgin PMMA (on the order of 20 times in terms of fracture toughness) but also compared to classical blends, by a factor from 2 to 4. Reinforcing glassy thermoplastics has been a major industrial challenge due to their usually brittle behavior in the temperature range they are used. This industrially scalable one-step process shows promises for the design of nano-laminated organic glasses with high impact resistance.