Synthesis of silica Janus nanosheets and their application to the improvement of interfacial interaction in wood polymer composites

Abstract The incompatibility between wood components and polymers negatively affects the physical and mechanical properties of wood polymer composites, which is still an obstacle to fabricating wood polymer composites with desirable performance. Inspired by the good compatibilization of Janus structure, silica Janus nanosheets were synthesized by sol–gel process and used to improve the interfacial interaction of methyl methacrylate (MMA)-impregnated wood in the present study. Results showed that the Janus nanosheets with smooth convex surfaces and rough concave surfaces were successfully synthesized. The thickness of Janus nanosheets was about 30 nm, and the length could be tuned by the time of the ultrasonication. With the addition of 0.5% nanosheets, the interface gaps between the polymer and wood cell wall were remarkably decreased compared to the MMA treated wood samples, indicating the efficient interfacial interaction due to Janus nanosheets. This improved interfacial interaction was also confirmed by the changes of the pore structure of MMA/Janus nanosheets-treated wood samples. The ASE of MMA/Janus sheets-treated wood was improved by 40% compared to MMA-treated wood samples. Compared to untreated wood samples, the water uptake of MMA/Janus sheets-treated wood was reduced by 61%, while the modulus of rupture and modulus of elasticity were improved by 31% and 45%, respectively, which were higher than MMA-treated wood. Moreover, the incorporation of silica nanosheets also improve the thermal stability of the MMA treated wood sample. This preliminary research will provide a new approach for enhancing the interfacial properties of wood polymer composites.