Water Resistance of Chitosan–Dopamine–Montmorillonite Film Added with LNP

Biobased films have attracted much attention of researchers due to the advantages of biodegradability and biocompatibility. Chitosan–dopamine–montmorillonite composite films were prepared using genipin as a cross-linking agent, based on a biomimetic strategy through the “brick–mortar”structure design. Lignin nanoparticles (LNP) were used to construct efficient surface structures to enhance the water contact angles, as revealed by the AFM images. SEM images showed that the chitosan, montmorillonite and dopamine formed a homogeneous film. XRD curves indicated that the addition of genipin caused the rearrangement of chitosan and montmorillonite molecules. The water resistance of the obtained composite films added with genipin cross-linked dopamine was significantly enhanced. The resultant film could maintain intact shape in the acidic and alkaline solutions (pH = 2, 4.5, 9 and 11), and the addition of 1.11% LNP obviously enhanced the water contact angle values, which could be above 100° in 60 s. The appropriate dosage of LNP improved the strength performance, while the dosage of LNP on the transmittance and thermal stability of chitosan composite film was not significant. These findings indicated that this simple method was greatly helpful for enhancing the hydrophobic application performance of chitosan-based composite film.