Nonsolvent-Induced Phase Separation–Jet Spinning: An Innovative Technique for Producing Cellulosic Nanofilms, Suspensions, and Nanofilm-Based Sponges

The development of biobased porous materials using straightforward procedures remains challenging. This study introduces nonsolvent-induced phase separation–jet spinning (NIPS-JS), an innovative technique for fabricating cellulose acetate nanofilms. Coupling nonsolvent-induced phase separation (NIPS) with the turbulent mixing effects of high-velocity coaxial jets, NIPS-JS, achieves rapid and efficient nanofilm formation (40–50 nm thickness), demonstrating production rates exceeding 0.8 g·min–1 and possessing adjustable parameters for optimization. The NIPS-JS technique holds promise for processing of diverse polymeric materials undergoing NIPS. Furthermore, this study demonstrates a novel application of NIPS-JS films for fabricating ultralight cellulosic sponges using cryo-templating and lyophilization, reducing the use of organic solvents and chemical cross-linkers. The resulting monolithic, three-dimensional networks, stabilized by robust lamination of individual thin films, exhibit ultralow density (5–10 kg·m–3), high porosity (>99%), and excellent stability. Notably, the addition of 0.2–1 wt % ethanol enhances the reproducibility of the cryo-templating step and minimizes shrinkage. This cost-effective and scalable approach offers a promising pathway for the production of innovative porous materials without chemical cross-linkers.