Growth and structure of poly(methyl methacrylate)/multi-walled carbon nanotube composites. Poly(methyl methacrylate) (PMMA)/multi-walled carbon nanotube (MWCNT) composites have been synthesized by grafting polymer chains on the surface of MWCNTs using hexamethylene diisocyanate as a crosslinker. Structure, morphology, and dispersion of MWCNTs in the PMMA matrix were investigated by X-ray diffraction, small-angle X-ray scattering, dynamic light scattering, scanning electron microscopy, and optical microscope. Different amounts of MWCNTs were added into the resin and the dispersion of the nanotubes in the polymer matrix was found to be better when less than 20% wt MWCNTs were added into the resin. The improvement of dispersion can be explained in terms of Van der Waals interactions. Different ratios of PMMA and MWCNTs significantly affect the physical properties of the resin composite. The surface tension of resin composite containing 40 wt % MWCNTs was much lower than that of pure PMMA. Moreover, the composite had a lower refractive index compared to pure PMMA. Finally, the degree of polymerization decreased by increasing the amount of MWCNTs. PMMA/MWCNT composites exhibit great potential for use in industrial applications, especially in coating, paints, and printing inks.