Lignocellulose aerogel from wood-ionic liquid solution (1-allyl-3-methylimidazolium chloride) under freezing and thawing conditions

This article reports a facile preparation of a lignocellulose aerogel from a solution of wood in an ionic liquid by cyclic freeze-thaw (FT) process. Trema orientalis wood flour was dissolved in 1-allyl-3-methylimidazolium chloride (AMImCl), an effective ionic liquid, and then repeatedly frozen at -20 °C and thawed at 20 °C for several times, and then finally regenerated in water. The hydrogel obtained was solvent-exchanged to acetone, washed with liquid carbon dioxide, and finally dried by releasing the carbon dioxide at critical temperature to obtain the lignocellulose aerogel. The aerogel had an open 3D fibrillar network and could be transformed from nanofibrillar to sheet-like skeletons with hierarchical micro- and nanoscale morphology and porosity by adjusting the FT treatment cycles. The frequency of FT cycles influenced the intensity, specific surface, crystallinity, and thermostability of the aerogel. This research highlights new opportunities for the development of porous and flexible aerogel scaffolds.