Functionalization of unzipped carbon nanotube via in situ polymerization for mechanical reinforcement of polymer

Multiwalled carbon nanotubes (MWNTs) have been widely used as mechanical reinforcement agents during the past decades. However, the complete achievement of mechanical enhancement has been greatly impeded by their limited available interfacial area (AIA) and weak adhesion force with the polymer matrix. In this paper, we use unzipped MWNTs (uCNTs) as a precursor to fabricate poly(methyl methacrylate) (PMMA) functionalized uCNTs (uCNTs-P) via in situ free radical polymerization. Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectra (XPS), Raman, and thermogravimetric analysis (TGA) are applied to characterize the structure of resultant uCNTs-P. The mechanical testing of composite films indicated that uCNTs-P were more effective than uCNTs and functionalized MWNTs in improving the tensile strength and Young's modulus. This excellent reinforcement is attributed to uCNTs-P's highly available interfacial area and the strong interlocking force with the polymer matrix. This study will guide the design of functionalized uCNTs and the preparation of high-performance polymer composites.