Eco-applications of Proteins: Glues, Foams and Coatings

Environmental and economic concerns have encouraged the development of materials derived from renewable resources, to replace those produced by petrochemicals. In particular, the abundance and high functionality of proteins make them an attractive raw material for polymers. Composed of numerous constituent elements, such as amino acids, proteins are complex macromolecules that can be described as biopolymers.

There is indeed growing interest in the use of proteins, of both plant and animal origin, for applications such as adhesives, foams and coatings. However, chemical or thermal modifications may be required before they can be used in different contexts, particularly where high performance is required. For example, due to the many polar groups present in proteins, the main hurdle to overcome is to make protein-based materials water-resistant.

Several industrial proteins are available for the development of technical applications, and offer numerous advantages, such as non-toxicity and low purchase cost. The use of proteins for non-food applications may be a promising way of producing biodegradable materials with a wide range of functional properties, thanks to their unique structure.

A number of long-standing technologies exist for efficiently cross-linking proteins. For example, certain amino acid groups react readily with aldehydes and other chemical compounds to form stable, cross-linked networks when heated. On the basis of this technology, a great deal of work has been carried out on the preparation of adhesives, foams and coatings based on wheat gluten, soy protein, albumin and whey, and will be presented in this article.