Lignin is a complex natural polymer and by-product of the pulp and paper industry. Currently, the increasing interest in bio-based products has motivated the search for alternative renewable feedstocks that can sustainably replace synthetic polymers. Because of the phenolic functionalities of lignin, this natural polymer has attracted interest for application in biomaterials. Among various products, polymeric foams stand out as a potential product in which lignin incorporation has resulted in improved mechanical and thermal properties. This paper reviews the state of lignin foam development, with emphasis placed on phenol-lignin types.

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Every year, over 8 million tons of crustacean shells are discarded. However, there exists an opportunity for valorizing the chitin and calcium carbonate part of the composition of the shells. Our study revealed crustacean chitin reduces self-aggregation effects. It was shown that crustacean-based nanofibers alone or added to cellulose offer unprecedented reductions in viscosity even after drying to produce foams impossible for cellulose. Polysaccharide nanofibers suffer from increased viscosity from strong hydrogen bonding addressed by the incorporation of crustacean-based nanofibers. The ability of the nanocomposite to overcome self-aggregation and collapse was attributed to organized chitin nanofiber morphology in the crustacean matrix. As a result of enhanced surface area from reduced fiber aggregation, the chitin/crustacean-cellulose blend was tested for a biomedical application requiring a high surface area: coagulation. Preliminary experiments showed the crustacean matrices, especially those containing calcium carbonate, induced blood clotting when 35 s. A materials platform is proposed for bio-based nanofiber production overcoming intractable and difficult-to-address self-aggregation effects associated with polysaccharides.