Optically transparent tough nanocomposites with a hierarchical structure of cellulose nanofiber networks prepared by Pickering emulsion method

Abstract Optically transparent tough cellulose nanofiber (CNF) reinforced composites were successfully prepared through a simple Pickering emulsion method. The emulsions of CNFs, acrylic resin monomer and water were vacuum filtered to form mats, and the mats were hot-pressed, and UV-cured. Hierarchical CNF networks where the homogenously-dispersed CNFs formed a network surrounding resin droplets in the composites were observed. As the CNF content increased, thicker CNF networks were formed, which could bear greater loads. The strength, modulus, strain and toughness of the composites with 25 wt% CNFs increased to be 18.6, 56.7, 1.5, and 36.3 times as great as those of the neat acrylic films with the great reduction in the thermal expansion to 7.3 ppm K-1 (1/26th of the neat polymer) and only 3% degradation in optical transmittance. The composites prepared by Pickering emulsion approach showed higher performances than those from the impregnation method, which could be used in optoelectronic applications.