Cellulose xerogels

X.J. Wu and M.M.F. Choi, An optical glucose biosensor based on entrapped-glucose oxidase in silicate xerogel hybridised with hydroxyethyl carboxymethyl cellulose. Anal. Chim. Acta 514, 219-226 (2004). 

Using a similar synthetic methodology, other water soluble polymers, such as poly(vinylpyrrolidinone) (PVP), polyfpropylene glycol) (PPG), and methyl cellulose (MCel) were intercalated into V20s.nH20 xerogels [41]. The ratio of intercalated polymer to the layered host could be synthetically manipulated. Similarly to PEO, PVP, PPG, and MCel could also function as solid electrolytes when complexed with lithium salts, and hence their relevance in lithium battery applications. The intercalation of PEO into V20snH20 was also reported by Ruiz-Hitzky et al. [42]. 

Cellulose and particularly nitrocellulose represent reversible xerogels showing the phenomena of limited and unlimited swelling respectively. In certain instances sorption of a vapour may give rise to continuous transitions between the xerogel state and the formation of a true solution. 

Cellulose and gelatin xerogels should be considered as a macromolecular glass or resin, comparable with other glasses, like for instance highly undercooled solid butanol, allowing for the presence of a crystalline portion in the former. 

Figure 10.23. Illustration of the shrinkage of cellulose acetate-based gels occurring during drying by evaporation. A wet gel (left) and the corresponding xerogel (right). The initial diameter of the wet gel is 3 cm [22].

Collodion can be considered as a oleogel of cellulose nitrate in a mixture of ether and alcohol to which castor oil is added. Collodion dries in on the skin to a kind of lipo-xerogel that sticks like a capping membrane. Collodion is therefore used to apply salicylic acid on warts. 

Similarities have been demonstrated in the ultrastructure of xerogels of cellulose isolated from Japanese pears and of chitin. ... 

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