Strong Adhesives from Corn Protein and Tannic Acid

Modern society is in great need of environmentally sustainable and low-cost alternatives to some petroleum derived adhesives. To allow recycling and avoid pollution, adhesives for single use products including packaging are of particular interest. Potential candidates for such applications are the adhesive formulations of corn zein protein and tannic acid presented here. High strength adhesive bonding is found when the formulations are optimized with regard to composition, pH, and curing temperature. Bonding is tested on aluminum substrates using lap shear configurations. Adhesion strengths exceed the minimal bonding of zein-only controls. Maximum adhesion for zein and tannic acid is as strong as commercial Super Glue when measured under similar conditions. The system forms nanometer and micrometer sized pores throughout the bulk adhesive. A low amount of tannic acid and neutral pH of the strongest adhesive make the corn zein-tannic acid system potentially appealing for cost efficient adhesives used in packaging, cosmetics, and other single use applications where biomedical grade purity is not required.