Interfacial assembly of nanocellulose microgels enhances thermal insulation of Pickering foam.

Nanocellulose has attracted extensive attention in the preparation of thermal insulation materials because of its high Young's modulus, high strength and low thermal expansion coefficient. In this study, nanocellulose microgels prepared by self-assembly of 2,2,6,6-Tetramethylpiperidoxyl oxidized nanocellulose (TOCNC) and Nisin were used as particle stabilizers, and acrylated epoxidized soybean oil (AESO) was used as oil phase to prepare Pickering emulsion, which was cured by heating to obtain biomass-based Pickering thermal insulation foam. Pickering foams prepared based on microgels with different Nisin contents have significant differences in thermal insulation performance. The results show that the addition of microgel particles can improve the thermal stability, increase the roughness of pore wall and reduce the thermal conductivity of AESO polymer foam. Among them, the Pickering foam prepared by microgel containing 0.06 wt% Nisin has the best thermal insulation performance and rougher pore wall surface, and its thermal conductivity is 0.040 W/(m·K), which is obviously lower than that of the foam prepared by TOCNC (0.083 W/(m·K)). Based on the structural design of nanocellulose microgel particles, this work innovatively realized the assembly of microgels at the oil-water interface and the regulation of thermal insulation performance through Pickering technology, and developed a biomass-based foam with improved thermal insulation effect, which provides a new idea for expanding the advanced application of nanocellulose in the field of thermal insulation materials.