Integration of PDA Chemistry and Surface-Initiated ATRP to Prepare Poly(methyl methacrylate)-Grafted Carbon Nanotubes and Its Effect on Poly(vinylidene fluoride)-Carbon Nanotube Composite Properties

Poly(methyl methacrylate)-grafted carbon nanotubes (PMMA@MWCNTs) are nondestructively prepared via the integration of mussel-inspired polydopamine (PDA) chemistry and the surface-initiated atom transfer radical polymerization (ATRP) method. The structures and properties of the poly(vinylidene fluoride)-based (PVDF-based) nanocomposites filled with pristine MWCNTs and PMMA@MWCNTs are investigated. The results show that the encapsulation of PMMA on the MWCNTs surface not only improves the dispersibility of MWCNTs in the PVDF matrix but also enhances the interfacial interaction between MWCNTs and PVDF. The addition of PMMA@MWCNTs nanofillers to PVDF can effectively induce the crystal structure of PVDF to transform from the alpha-phase to the beta/gamma -phase, and nearly 100% beta/gamma -phase PVDF formed when the nanofiller loading is higher than 5 wt%. Compared with the MWCNTs/PVDF composites, the PMMA@MWCNTs/PVDF composites exhibit obvious improvement in the percolation threshold because the PMMA shells hinder the direct contact of the MWCNTs. Moreover, the loss tangent of the PMMA@MWCNTs/PVDF composites is effectively suppressed due to the reduced leakage current in the composites and the enhanced interfacial strength between the nanofiller and the matrix.