Soybean oil-based random copolymers based on hydrogen bond crosslinked networks as reprocessable, recyclable and multifunctional adhesive materials

Abstract

Adhesive industry transformation toward a formaldehyde-free and pollution-free society demands adhesive materials to be reprocessable and recyclable in circularity in an efficient and green manner. Recent advances in adhesive material have bestowed random copolymer such as vitrimer with reprocessability and recyclability, providing a way for the circular manufacturing of adhesive materials. However, reprocessability and recyclability of mechanically robust vitrimers typically requires high temperatures, high pressure and long processing time, which leads to lower practicability and economy of adhesive material. Here, a series of soybean oil-based polymers (SOPs) based on hydrogen bond crosslinked networks were fabricated by random polymerization via a solvent-free curing strategy under ultraviolet (UV) irradiation, and used as adhesive material. The introduction of multiple hydrogen bond interactions with reversible dissociation and association effects provide materials with adjustable mechanical strength, self-healing, adhesion and shape memory properties. Glass transition temperature of the polymers was manipulated via changing the ratio of soybean oil-based monomers (SOMs) and allyl thiourea. SOPs can effectively adhere to wood, metal, rubber, glass and PTFE. The dry shear strengths of wood substrate and steel substrate were 2.21 MPa and 2.06 MPa. SOPs based on multiple hydrogen bonds showed excellent self-healing and could be used to repair balloons and tires, etc. SOPs/carbon nanotubes (CNTs) composites exhibited adjustable electrical conductivity and was used as electric conductive adhesive. This work provided a facile and sustainable strategy to fabricate multi-functional and recyclable soybean oil-based adhesive, and SOPs/CNTs composites with outstanding electrical conductivity broadened their applications.