Cellulose nanocrystals/poly(methyl methacrylate) nanocomposite films: Effect of preparation method and loading on the optical, thermal, mechanical, and gas barrier properties

Rod‐shaped cellulose nanocrystals (CNCs) with aspect ratio of 17.10 were prepared from microcrystalline cellulose using sulfuric acid hydrolysis method. CNCs/poly(methyl methacrylate) (CPM) nanocomposites were fabricated in two different ways, including in situ prepared CPM nanocomposites (ICPM) and ex situ prepared CPM nanocomposites (ECPM). The ICPM nanocomposites were first synthesized via free radical graft copolymerization with initiator ceric ammonium nitride (CAN), and then prepared by solution casting method. The ECPM nanocomposites were prepared by solvent exchange and solution casting method. Characterizations of ICPM nanocomposites were fully conducted. Grafting was verified by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR), and the molecular weight of graft chains were determined using gel permeation chromatography (GPC). The performances of ICPM and ECPM nanocomposite films were studied with field emission scanning electron microscopy (FE‐SEM), ultraviolet–visible (UV–vis) transmittance spectroscopy, wide‐angle X‐ray Diffraction (WXRD) patterns, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile test and oxygen permeation analysis. ICPM nanocomposite films showed superior optical, thermal, mechanical and gas barrier properties to ECPM nanocomposite films. POLYM. COMPOS., 38:E137–E146, 2017. © 2015 Society of Plastics Engineers