Physically crosslinked tannic acid-based adhesive for bonding wood

Adhesives are widely used in daily life. However, during their preparation or application, traditional adhesives easily release toxic gases, which adversely affect the human body and the environment. Herein, a physically crosslinked tannic acid (TA)-based adhesive is prepared by forming hydrogen bonding between cellulose nanocrystals (CNCs), polyacrylamide (PAM), and TA. Different characteristics of the prepared adhesives, including morphology, water content, biocompatibility, curing time, and adhesion properties, were investigated. Lap shear strength of the adhesive depends on the water content and curing time, reaching a maximum at a curing time of 48 h. The addition of CNCs enhances the lap shear strength, with the adhesive sample with 6.0 g CNCs exhibiting a high lap shear strength of 5.5 MPa on wood, which is 34% higher than that of the PAM/TA adhesive. Moreover, TA-based adhesives have excellent biocompatibility. These CNC/PAM/TA adhesives have excellent potential for application in the furniture, construction, and building industries.