Remarkable toughness reinforcement of elastomer with cellulose microgel: Employing polymer matrix and cellulose nanofiber network as the continuous phase and energy dissipation agent

Abstract

Double-network reinforcement strategy has been widely used to improve hydrogels' toughness but is rarely applied in bulk polymer. The key to this strategy is introducing sacrificial bonds to improve strength and maintain the integrity of the polymer matrix at high elongation, dissipating applied energy as much as possible. In this study, a micron-sized microgel was employed as a sacrificial agent to reinforce polymer matrix. A simple and versatile process was introduced for the fabrication of cellulose microgel/ poly(butyl acrylate(BA)-co-methyl methacrylate(MMA)) nanocomposites by in situ free-radical polymerizations of BA and MMA complex monomer solution contained with well-dispersed cellulose microgels. After polymerization, the microgels were found homogeneously distributed within the polymer matrix. The organic-phase bacterial cellulose microgels (OB-microgel) reinforced polymer exhibited marvelous performance in the tensile test. The ultimate strength, Young's modulus, and toughness of P(BA-co-MMA) reinforced with 1.0 wt% OB-microgel were 1.13 MPa, 1.09 MPa, and 1.11 KJ m−3, about 2–3 times higher than neat P(BA-co-MMA) respectively. Moreover, a high strain to failure similar to the neat P(BA-co-MMA) was maintained. This reinforcement was mainly attributed to the sacrificing effect of microgel, not the formation of a percolation network, which was also supported by DMA test. Hence, cellulose microgel consisting of cellulose nanofiber network was demonstrated to be an efficient energy dissipation agent for the continuous phase of the polymer matrix to acquire high strain to failure and high tensile strength.