Engineering the Interphase of Single Wall Carbon Nanotubes/Polyacrylonitrile Nanocomposite Fibers with Poly(methyl methacrylate) and Its Effect on Filler Dispersion, Filler–Matrix Interactions, and Tensile Properties

Mechanical reinforcement of polymer nanocomposites with pristine single wall carbon nanotubes (SWNTs) beyond 1 wt % loading is challenging because SWNT–SWNT contacts generate filler aggregation and reduce polymer–filler interaction. Furthermore, SWNTs cannot be covalently functionalized without affecting their inherent properties. In this study, filler individualization and filler–matrix interactions were tuned by helically wrapping the SWNTs with poly(methyl methacrylate) (PMMA), a noncovalent method, and also by changing the PMMA molecular weight. Polyacrylonitrile nanocomposite fibers were produced by dry-jet wet spinning using 1 and 5 wt % PMMA-wrapped SWNTs. Improvement in the filler dispersion and the fiber mechanical properties upon using PMMA-wrapped SWNTs, as compared to SWNTs without PMMA-wrapping, is reported. It is demonstrated that PMMA-wrapping becomes part of the filler–matrix interphase. Increasing the molecular weight of the PMMA wrapping improves SWNT individualization but appears to reduce filler–matrix interaction. Relatively high fiber mechanical properties were obtained when SWNTs wrapped with relatively low molecular weight (15000 g/mol) PMMA were used. Potential applications of these fibers have been discussed.