Endowing water-based polyacrylics adhesives with enhanced water-resistant capability by integrating with tannic acid

Water based polyacrylics adhesives is of great need in modern society due to their eco-friendly nature as well as cost effectiveness. However, despite the strong adhesion capability of polyacrylics in anhydrous state, achieving a reliable adhesion under moisture or underwater conditions remains a great challenge. Herein, a polyacrylates-containing supramolecular adhesive with enhanced water-resistant capability was successfully designed and fabricated by integrating tannic acid (TA) with poly(2-hydroxyethyl acrylate-co-acrylic acid) (P(HEA-co-AA)) through hydrogen-bonding driven co-assembly. The multiple hydrogen-bonding interactions between P(HEA-co-AA) and TA were investigated by FTIR and DFT calculation. Owing to the presence of abundant polar groups including carboxyl, hydroxyl, catechol and pyro-gallol, the supramolecular adhesives exhibit a maximum adhesion strength of 4.1 MPa on Al sheets, which is 1.5 times stronger than that of P(HEA-co-AA) under the same conditions. Moreover, 10 wt% of TA could dramatically increase the water resistance of P(HEA-co-AA)/TA supramolecular adhesive, which could maintain about 2.8 MPa of the joint strength on Al sheets after 3 h underwater immersion, far surpassing several commercial adhesives, and pristine P(HEA-co-AA), which is completely failed underwater. Overall, this work provided a “green” alternative to improve the water-resistance of water-based polyacrylics adhesives.