Chitosan: Emergence as potent candidate for green adhesive market

• Chitosan has been emerged as potential candidate of natural adhesive.
• Its biological properties are of great interest for bonding applications.
• NH2 group of chitosan offer more ionic interactions for negatively charged adherends.
• Its higher degree of deacytylation and Mw supports improved adhesion properties.
• Additive blending and cross-linking of plasticizer increases its bonding strength

Chitosan has gained significant attention during last decades as a potent natural adhesive. Its lower concentrations (<10% w/v) offer competitive strength as synthetic adhesives which would reduce economic constrains of adhesive production. There is increasing commercial interest on chitosan as it possesses biodegradability, biocompatibility, non-toxicity and anti-microbial properties which are of high interest for industries and consumers. Moreover, it has reactive amino side groups, which offer possibilities of chemical modification, increased ionic interactions and graft-reactions etc. Degree of deacetylation (DD) and molecular weight (Mw) is important in bonding mechanism. Most of the synthetic adhesives are comprised of petrochemicals that leave toxic residues such as formaldehyde and volatile organic compounds (VOCs), which are injurious to health and environment. Therefore, development of cost-effective, environmental and health-friendly green adhesives, based on renewable resources is main interest of adhesive industries these days. Rising oil prices are another driving force in research for development of bioadhesives as substitute of synthetic adhesives. This review is focused on current developments of chitosan adhesives for structural and general bonding applications during last decades as well as its current market potential worldwide.