Structure and mechanical properties of Poly(styrene-co-acrylate)/cellulose nanocrystals co-continuous composites via one-pot pickering emulsion polymerization

Nanoparticle-doped polymeric composites usually suffer from poor mechanical toughness and strength, due to the hard formation of co-continuous submicron structure between matrix and nanoparticles. Here, a universal strategy to construct a co-continuous submicron structure in nanoparticle-doped polymeric composites was proposed for significant mechanical enhancement via integrating Pickering emulsion and copolymerization. The surface-grafted cellulose nanocrystals (CNCs) acted as the solid surfactant of Pickering emulsion forming an isolated percolation network, combined with the copolymerization of surface-grafted CNCs and polymer matrix, generating stronger interaction in composites. The poly(styrene-co-acrylate)/methylacryloyl-grafted CNC (PSA/mCNC) composites were obtained from one-pot Pickering emulsion polymerization. The tensile strength and the elongation at break of PSA/mCNC composites increased by 107% and 681%, respectively, when mCNCs were 0.5 wt%. The mechanical performance of PSA/mCNC composites exceeded the best PSA/CNC composites, whose tensile strength and the elongation at break only increased by 51% and 650%, respectively. The PSA/mCNC composites showed higher mechanical performance and simpler post-process, compared with similar commercial products. This strategy is universal for mechanical enforcement of other polymeric composites.