Modification of cellulose nanocrystal via SI-ATRP of styrene and the mechanism of its reinforcement of polymethylmethacrylate

•Cellulose nanocrystals were grafted with polystyrene via SI-ATRP.•The functionalization of the CNC surface favored its dispersion in the PMMA matrix.•The thermal and mechanical properties of PMMA were improved with reinforcement of CNC.•The transparency of nanocomposites was particularly presented.

Cellulose nanocrystal (CNC) is a promising strengthener but is used limitedly since its poor compatibility with organic materials. The graft polymerization of styrene via surface-initiated atom transfer radical polymerization (SI-ATRP) of cellulose nanocrystal is adopted to modify its thermo-stability and compatibility. The modified crystals have been dosed into polymethylmethacrylate (PMMA) nanocomposites by the solution casting. The polymeric layer on the surface of CNCs should improve the thermal stability of CNCs, and provide significant dispersibility and compatibilization for the nanocomposites. Thermogravimetry analysis proved that the initial degrade temperature of CNC was increased 50 °C with the modification. The scanning electronic microscope showed that the modified CNCs homogeneously dispersed in PMMA matrix. Breaking strength and elongation at break of the composites were improved, which was attributed to the reinforcement of CNCs modified with styrene. Transmittance of nanocomposite films measurement showed that the transmittance of PMMA/1%CNC was almost close to that of pure PMMA.