Chitin Nanofibrils to Stabilize Long-Life Pickering Foams and Their Application for Lightweight Porous Materials

The demand of sustainable development is challenging researchers to convert renewable resourced biomass into functional materials via environmentally friendly and sustainable pathways. This work introduces a long-life Pickering foam stabilized by chitin nanofibers (CNFs) as colloidal rod-like particles, and a facile method for fabricating lightweight porous solid foams that recycles biomass materials derived from seafood waste. These foams were formed by combining nonionic surfactant Tween 20 (T20) and CNFs, with the CNFs being irreversibly adsorbed at the air–water interface to provide Pickering stabilization. At a concentration of 7.5 mg/mL, the foams could be stable for over 1 week without any apparent drainage. The rheological data indicated the formation of gel networks by self-aggregated CNFs at the air–water interface, which provided long-term stabilization by preventing foam coalescence and disproportionation. This long-term stability of CNF-T20 wet foam has permitted the fabrication of solid porous matrix by removal of the water through simple air-drying. The air-dried chitin foams were ultralight weight porous materials with porosity of 99.4% and a density of 8.84 kg/m3. In addition, they exhibited significantly improved mechanical performance (Young's modulus of ∼290.2 kPa) compared to porous chitin materials of comparable densities prepared by a traditional freeze-drying method. Therefore, this research has provided a convenient pathway for scalable processing of macroporous material from renewable biomass for potential applications in packaging, pollutant treatment, catalysis, tissue engineering and other related fields.