Embedding graphene nanoparticles into poly(N,N′-dimethylacrylamine) to prepare transparent nanocomposite films with high refractive index

Transparent nanocomposite films of (graphene nanoparticles)-poly(N,N'-dimethylacrylamide) (GNPs-PDMAA) with a high refractive index are prepared via a facile in situ polymerization method. The structure and properties of GNPs and the nanocomposite films were studied by X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, and transmission electron microscopy (TEM), which indicate that GNPs with a diameter of 3-5 nm have been successfully immobilized into the polymer matrix and are homogeneously dispersed in PDMAA. The GNPs-PDMAA nanocomposite films exhibit good transparency in the visible range. The refractive index of the transparent GNPs-PDMAA nanocomposite films is in the range from 1.516 to 1.976 at 632.8 nm, which linearly increases with the content of GNPs from 0 to 50 wt%. It is also found that the transparent nanocomposite films can be prepared using mixed monomers containing N, N'-dimethylacrylamide (DMAA) and styrene (St) at an equal weight ratio following the UV/thermal dual-cure process. The refractive index of the nanocomposite film reached 2.058 with 50 wt% contents of GNPs. Our study provides a facile and feasible route to produce transparent nanocomposite films with tunable refractive indices for potential optical applications.