Mesoporous xerogel cellulose composites from biorenewable natural cotton fibers

All-cellulose xerogel composites were fabricated using a facile, scalable three-step process-(1) partial ionic liquid dissolution, (2) non-solvent rinsing, and (3) drying. The xerogel composites are composed of two phases where the yarn center is non-porous highly crystalline cellulose I surrounded by mesoporous amorphous regenerated cellulose. The composite had high 149 m2 g-1 Brunauer-Emmett-Teller (BET) surface area with 11.7 nm average pore diameter. The porosity was calculated using density-based (phi rho = 0.49) and volume-based (phi V = 0.52) methods. The porosity evolution mechanism is attributed to non-solvent-induced polarity shifts, and these results are compared with non-porous morphologies produced by varying the choice in non-solvents. Although similar decrystallization behavior was measured for all samples, non-porous yarns had a smaller diameter and significantly reduced BET surface area (0.03 m2 g-1). The presented fabrication method offers controllable mesoporous phase formation along with freestanding structural capability towards the development of advanced functional cellulosic materials.