Design and Preparation of a High Mechanical Strength Recyclable Polyurethane Adhesive Based on Dynamic Disulfide Bonds

Abstract

To overcome the major limitations of poor mechanical properties of traditional polyurethane adhesives and improve their low reuse efficiency, a series of thermoplastic polyurethane adhesives, named 2SPU, were obtained by combining polyester polyols: poly-1,4-butanediol adipate (PBA), self-made soybean oil-based polyols (MESO), and toluene diisocyanate (TDI), and incorporating dynamic disulfide bonds to introduce thermal cycling function. Properties analysis shows that when the synthesized polyurethane adhesive contain 5% 2,2′-dithiodianiline (2-AFD), it exhibits great mechanical strength and good self-healing ability (compared to the adhesive without disulfide bonds, its shear strength increases from 43.38 to 118.08 MPa and its initial repair efficiency could increase from 24.4% to 96.6%). SEM clearly shows the self-healing process. These polyurethane adhesives based on SS chain exchange reaction has great application potential as a dressing for promoting the recycling of high bonding strength adhesives.