Cellulose-based aerogel fibers with enhanced mechanical properties for thermal insulation and humidity response

Aerogel fibers have emerged as ideal materials for thermal insulation, due to the high porosity, low thermal conductivity, and unique nano-gel network structure. However, they typically suffer from poor mechanical properties and limited functionality. Herein, bacterial cellulose/graphene oxide (BC/GO) aerogel fibers were prepared via wet-spinning with surface modification by polydiallyldimethylammonium chloride (PDDA). The results demonstrated that the aerogel fibers exhibit satisfactory thermal insulation performance, attributed to their high porosity (82.3 %) and tiny pore size (<50 nm). Besides, the bacterial cellulose/graphene oxide/ polydiallyldimethylammonium chloride (BC/GO/PDDA) aerogel fibers showed enhanced mechanical properties with a tensile strength of 0.409 MPa, an elongation at break of 50.91 %, and a toughness of 140.44 kJ m^-3. As the relative humidity increased, the ions of PDDA were released resulting in augmented electrical conductivity of the composite aerogel fibers. When applied to a simulated respiration process, the BC/GO/PDDA aerogel fibers displayed a fast response time of 1.8 s and a high sensitivity. This work broadens the application prospects of bacterial cellulose aerogel fibers, which have great potential in thermal insulation fabrics and flexible wearable sensors.