In situ atom transfer radical polymerization of styrene to in-plane functionalize graphene nanolayers: grafting through hydroxyl groups

Graphene oxide (GO) was modified with two different amounts of 3-(trimethoxysilyl) propyl methacrylate (MPS) by a silane coupling reaction. Atom transfer radical polymerization of styrene in the presence of different amounts of MPS-modified graphene was carried out to evaluate the effect of graphene loading along with the graft density on the properties of the products. Successful attachment of MPS on the surface of GO was evaluated using Fourier transform infrared spectroscopy. Expansion of graphene interlayers by oxidation and functionalization processes was evaluated using X-ray diffraction. The ordered and disordered crystal structure of carbon in pristine and surface modified graphenes was evaluated by Raman spectroscopy. Relaxation behavior of polystyrene chains in the presence of graphene layers and also effect of graft content on the chain confinement was studied using differential scanning calorimetry. High-density nano-composites show much increase of T-g by addition of graphene content. Morphology of graphene nanolayers after modification processes was studied by scanning electron microscopy and also transmission electron microscopy. Flat and smooth morphology of graphene nanosheets was disturbed during the oxidation and functionalization processes and consequently wrinkled sheets with curvature were obtained.