Biodegradable Polyurethane Non-tackifier Pressure-Sensitive Adhesive Derived from Cashew Nut Shells

Abstract

Pressure-sensitive adhesives (PSAs) are widely used in applications such as sticky notes, tapes, and labels. However, most commercial PSA materials are fossil-derived and essentially non-degradable, leading to significant environmental concerns. Accordingly, the development of sustainable PSAs with competitive adhesion properties is of urgent importance. In this study, we synthesized polyurethane-based PSAs derived from cardanol, a renewable byproduct of cashew nut shells. The resultant adhesives exhibited excellent adhesion strength without plasticizers or tackifiers, which is attributed to the bulky side chains of cardanol, in synergistic combination with hydrogen bonding urethane linkages, as systematically demonstrated through thermal and viscoelastic analyses. Furthermore, the adhesives demonstrated rapid hydrolytic degradation under mild conditions, offering a potential solution to adhesive residue issues in pulping and recycling facilities.This work provides a promising strategy for the development of high-performance, degradable PSAs from renewable feedstocks, advancing the design rule of environmentally friendly adhesive technologies.