A novel, hydrophobic and highly-transparent composite film was conveniently prepared by coating stearic acid on the surface of cellulose nanofibril sheets. The surface morphology, chemical structure, mechanical and permeability properties of the stearic acid-coated nanocellulose film (SA-NF) were investigated with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), optical transmittance (Tr), tensile testing, water contact angle (WCA), water vapor transmission rate (WVTR) and oxygen transmission rate (OTR). The results demonstrated that the thin stearic-acid layer was successfully coated on the NF. The hybrid film maintained the high transparency of the unmodified NF sheet (Tr of 40.8%). Moreover, its surface hydrophobicity (water contact angles of 74.18°) and mechanical properties was apparently improved. And the barrier performance to water vapor and oxygen were declined in comparison with NF. Simultaneously, the SA-NF was flexible and eco-benign, which exhibited the greatly potential applications in biodegradable water-proof packaging.

nanocellulose film,stearic acid,transparency,hydrophobicity