High mechanical performance chitosan reinforced cellulose aerogel fibers with atmospheric pressure drying for thermal insulation

Abstract

Cellulose aerogel fibers with their unique combination of high porosity, low density, and robust mechanical properties, show great promise as candidates for thermal insulation materials and flexible devices. However, their mechanical performance is inherently limited, and conventional drying techniques such as freeze-drying (FD) and supercritical drying (SCD) are both time-consuming and energy-intensive, posing significant challenges for large-scale industrial applications. Atmospheric pressure drying (APD) has emerged as a simple and cost-effective alternative, demonstrating considerable potential in the fabrication of aerogel fibers. In this study, chitosan was incorporated during the dissolution stage to reinforce the cellulose framework. Following solvent exchange, the material was subjected to APD in an oven, resulting in the fabrication of low-shrinkage chitosan-reinforced cellulose aerogel fibers (CKAF). The porosity of CKAF can be controlled between 38 and 75% by selecting solvents with different surface tensions for solvent exchange and adjusting the affinity between the solvent and the CKAF framework during APD. The shrinkage of atmospheric pressure drying chitosan-reinforced cellulose aerogel fibers (APD-CKAF) with a chitosan content of 10% to cellulose was 11%, which was only 1.9% higher than that of FD (9.1%). However, the pore structure of the APD-CKAF is compact and uniform, with a pore size distribution ranging from 0 to 48 nm, primarily centered around 20 nm, and a porosity of approximately 75%. The APD-CKAF exhibits superior mechanical strength (22.1 MPa, a 16.3% improvement over the FD samples) and elongation at break (55.1%, a 111.5% increase compared with the FD samples). The APD-CKAF exhibits excellent thermal insulation properties over a wide temperature range. This study presents a low-cost and high-efficiency strategy for the fabrication of cellulose aerogel fibers, advancing their potential for thermal insulation applications.