Cellulose gel and aerogel from LiCl/DMSO solution

Recently-discovered lignocellulosic solvent, 8%(w/w) lithium chloride/dimethyl sulfoxide (LiCl/DMSO), was found to dissolve cellulose of varied crystal forms and degree of polymerization. Cellulose samples could be activated for dissolution by complexation with ethylenediamine (EDA), giving EDA contents of 20–23% (w/w) in the complex irrespective of the cellulose type. The cellulose solution gave well-resolved ¹³C NMR spectrum, confirming molecular dispersion. Cellulose could be coagulated by ethanol to give translucent cellulose gels, which could be converted to highly porous aerogels via solvent exchange drying. Nitrogen adsorption analysis gave their specific surface areas of 190–213 m²/g, with typical mesopore sizes of 10–60 nm. Scanning electron microscopy revealed the network structure of aerogel composed of relatively straight fibril segments, approx. 20 nm wide and 100–1,000 nm long. X-ray diffraction showed that the material is poorly crystalline cellulose II.