A platform for more sustainable chitin films from an ionic liquid process†
A versatile platform for the preparation of chitin films with tunable strength, morphology, and efficacy of application has been designed from an ionic liquid process for the production of more sustainable high value materials. Films were prepared by a simple casting method from a solution of chitin in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]). The chitin source, the loading in ionic liquid, and the drying methods defined film properties such as strength, porosity, and water absorbency. Only chitin directly extracted from shrimp shells using the ionic liquid (rather than commercially available chitin) could be used to cast films strong enough to be handled and dried. The optimal loading of chitin in the ionic liquid was determined to be 2.5 wt% and different drying methods led to different film properties (e.g., hard and rigid vs. soft and porous). As an exemplary application, loading and release of a model drug (caffeine) was investigated. Interestingly, a burst release of the majority of the caffeine was observed in the first 20 minutes, followed by slow release of the remainder. Although more investigations are needed, the chitin film platform can be thought of as an attractive new tool in the development of packaging materials, biomedical devices, and absorbent materials (M. Rinaudo, Prog. Polym. Sci., 2006, 31, 603–632) made from one of Nature's most abundant polymers.