Durability of biomineral-reinforced biopolymer adhesives following humidity and temperature exposures

Abstract

Conventional adhesives often use fossil fuel-based raw materials and release volatile organic compounds harmful to human health. Biobased adhesives may be eco-friendly and non-toxic alternatives, but their use has been limited in part because of poor mechanical performance and water resistance. Recent work demonstrates that precipitation of calcium carbonate in association with ureolytic bacteria or plant-based ureases increases the adhesive strength of biopolymer adhesives. However, the water resistance and thermal stability characteristics of these biomineral-reinforced biopolymer adhesives have not yet been evaluated. In this work, we tested the performance of biomineral-reinforced adhesives after moisture and a range of temperature exposures. We found that the adhesives retain their adhesive strength from below freezing to room temperatures and after prolonged exposure to moderate (50 % relative) humidity. The structural integrity of the adhesives is compromised at high humidity or temperature exposures due to solubility and limited thermal stability of the organic biopolymers. These findings open opportunities for future improvements in the design of biomineral-reinforced adhesives.