One-pot preparation strategy for anti-freezing, conductive hemicellulose-based deep eutectic gels

As a class of natural polysaccharide, hemicelluloses possess significant potential for applications in biosensors, drug carriers, energy storage, and other fields. However, its tight binding with cellulose/lignin result in a complex and inefficient extraction process. Furthermore, the subsequent steps for material conversion are highly cumbersome. In this study, the solubility and lignin selectivity of a choline chloride-monoethanolamine deep eutectic solvent (DES) as a green solvent for eucalyptus hemicellulose dissolution was investigated. Deep eutectic conductive gels were prepared directly from DES extract of eucalyptus by adding polyvinyl alcohol (PVA) and using a freezing-thawing method. The solubility of eucalyptus hemicellulose in DES reached 288.13 mg/g with high selectivity over lignin. The extraction yields of hemicelluloses from milled eucalyptus wood and eucalyptus holocellulose using DES were 5.02 % and 12.01 %, respectively, confirming the suitability of this DES system for the green extraction of hemicellulose from eucalyptus. The hemicellulose-based deep eutectic gels showed excellent electrical conductivity and freeze resistance. The T_g of the gels reached -104.9 °C, the conductivity of the gels at room temperature and - 80 °C reached 6.01 mS/cm and 2.39 mS/cm, respectively. The hemicellulose-based deep eutectic gels showed high sensitivity of resistance signal to deformation, indicating its potential applicability as strain sensors.