Reinforcement and plasticization of PMMA grafted MWCNTs for PVDF composites

Poly (methyl methacrylate) (PMMA) grafted carboxyl-modified multiwalled carbon nanotubes (MWCNTs–COOH), synthesized through emulsion polymerization, were introduced into polyvinylidene fluoride (PVDF) by solution blending. MWCNTs–COOH aggregated easily in PVDF matrix and the reinforcing effect for the matrix became notable only when the MWCNTs–COOH network structure was formed. However, the grafted PMMA chains on the surface of MWCNTs–COOH reduced the inter-tube interactions and greatly improved the dispersion of MWCNTs in the PVDF matrix. In this case, low grafting degree of PMMA was beneficial to the formation of MWCNTs–COOH network, while high grafting degree of PMMA led to that the contact between MWCNTs became less possible and the network structure of MWCNTs was hard to form. The grafted PMMA chains at high grafting degree showed a plasticization effect in the melt state.