Cellulose gel and aerogel from LiCl/DMSO solution

Abstract

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 13 C 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 m 2 /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.

Super water absorbing and shape memory nanocellulose aerogels from TEMPO-oxidized cellulose nanofibrils via cyclic freezing–thawing

“…Cellulose aerogels can be fabricated from either homogeneous cellulose solutions [18][19][20][21][22][23][24][25] or heterogeneous aqueous nanocellulose suspensions. 4,7,11,13,[26][27][28][29][30][31][32][33][34] Aerogels prepared from cellulose solutions require lengthy, multiple steps of dissolving cellulose in solvents, such as alkali hydroxide/urea solution, 18 calcium thiocyanate tetrahydrate, 19 N-methyl-morpholine-N-oxide, 20,21 sodium hydroxide, 22 lithium chloride/dimethylacetamine, 23 lithium chloride/dimethyl sulfoxide 24 and ionic liquid, 25 followed by induced gelation, solvent exchange and supercritical or freeze drying.…”

Direct preparation of green and renewable aerogel materials from crude bagasse

“…5, the bagasse aerogels possessed wide mesopore size distributions, mainly in the range of 2-30 nm. In comparison to cellulose aerogels prepared from DMSO/LiCl solution (Wang et al 2012), the bagasse aerogels displayed a narrow mesopore distribution and small average pore diameter. The difference was probably attributed to the freezing-thawing treatment applied in the preparation of bagasse aerogels.…”

“…The results showed that the bagasse aerogels had high specific surface area with a maximum of 185 m 2 /g, substantially higher than those of lignocellulosic aerogels (2-7.5 m 2 /g) prepared from wood solution in IL by cyclic freezing-thawing process followed by supercritical CO 2 drying Lu et al 2012), which was the most effective drying method to prepare homogeneous cellulose aerogels (Hoepfner et al 2008). The BET surface area of the prepared bagasse aerogels was also higher than that of the wood aerogel (80.7 m 2 /g) prepared from hardwood in IL 1-allyl-3-methylimidazolium chloride with 5 cyclic freezing-thawing treatment (Lu et al 2012) and that of wood aerogel (122 m 2 /g) prepared from spruce wood solutions in IL 1-butyl-3-methylimidazolium chloride with supercritical carbon dioxide drying (Aaltonen and Jauhiainen 2009), and nearly comparable to those of cellulose aerogels (190-213 m 2 /g) prepared from DMSO/LiCl solutions via solvent exchange drying (Wang et al 2012). The high BET surface area of the aerogels suggested that DMSO/LiCl is an ideal solvent system to prepare aerogels from crude bagasse.…”

Highly tough cellulose/graphene composite hydrogels prepared from ionic liquids

“…Natural biomass such as chitin (Hu et al, 2007(Hu et al, , 2011, chitosan (Berger et al, 2004), alginate (Augst et al, 2006), hyaluronic acid (Burdick and Prestwich, 2011), cellulose (Chang et al, 2010;Wang et al, 2012b) etc., are promising materials for preparing hydrogels due to their excellent biodegradability, hydrophilicity, biocompatibility, low toxicity and readily availability from the renewable resources. In the past a few decades, hydrogels from natural polysaccharides have been intensively studied and applied in food, wastewater treatment, sensing, wound dressing, drug delivery and tissue engineering Matricardi et al, 2013;Paulino et al, 2011).…”