Biobased functional coatings for cellulosic substrates

Cellulosic substrates, as renewable and recyclable items, are highly used in the packaging and personal care field. However, to expand their use and improve their properties, the application of a functional coating improving the barrier to oxygen, water vapour of the substrate is fundamental in packaing applications. Moreover, to confer anti-microbial/anti-oxidant properties to substrates addressed to personal care applications can be really usefull. This coating should be biobased and not affecting the end-of life of the final packaging or personal care product (recycling and/or composting). Several coatings were proposed based on biopolymers like proteins, chitin or cutin [1]. Chitin is a very abundant polymer available from crustaceans exoscheletons (sea food waste), from insects or from mushrooms. It can be converted to chitin nanofibrils or chitosan on the basis of the adopted process. Chitin nanofibrils (CN) and chitosan based coatings can confer to cellulosic board anti-microbial properties, so they can be considered as functional coatings for increasing the shelf life of packaging for fresh food [2], but also as anti-microbial/skin-regenerative additives for applications considering the contact with human skin [3]. We report the results related to the application of chitin derivatives to several cellulosic substrates with different thickness and mechanical properties. Cellulosic board and tissue will be compared not only in terms of the capacity of chitin nanofibrils to confer anti-microbial properties, but also considering their impact onto mechanical properties. The application of these functional biopolymers to cellulosic substrates could occur by using both liquid or solid coatings [1], that can be prepared by peculiar polymer processing methodologies. All these possibilities could represent valid alternatives to fossil coatings in the future.