Hierarchically oriented structure and enhanced toughness achieved by in situ microfibrillation of Polymethyl Methacrylate and Polyacrylate@rGO microspheres

Oriented structures with peculiar effects are widespread in nature but less common among artificial general materials. In order to develop composites with uniformly dispersed and oriented inorganic particles on large scale, Polyacrylate(PAcr)@rGO microspheres were fabricated by suspension polymerization and blended with Polymethyl Methacrylate (PMMA) to form PMMA/PAcr@rGO composites via in situ microfibrillation. The structure and mechanical properties (tensile strength, elongation at break and fracture energy) of the composites were investigated by transmission electron microscopy , scanning electron microscopy and universal material testing machine. As a result, the tenacity of composites was enhanced significantly with the dispersion phase of PAcr@rGO-0.15, where the elongation at break and the fracture energy were increased by ∼300% and ∼500% when compared to pure PMMA. During the melt blending process, PAcr@rGO microspheres were deformed into microfibrils through in situ microfibrillation, and the rGO was uniformly dispersed and oriented along the stretching direction as the microfibrils evolved. With the rGO fraction within 0.2 wt%, the highest degree of deformation for PAcr@rGO microfibrils was achieved with aspect ratio of ∼68 when 0.15 wt% rGO was added. As such, the movement of rGO particles was limited and aligned with the encapsulation and deformation of PAcr microspheres, which could be a good guidance to improve the dispersion of filler with alignment controlling for functional composites.