Sustainable and Renewable Microcross-Linked Polyurethane Pressure-Sensitive Adhesive from Waste Polyethylene Terephthalate

Recycling of sustainable raw materials from waste poly(ethylene terephthalate) is a promising production path compared to traditional raw materials sourced from limited fossil fuel resources. The renewable resources have potential in preparing polyurethane (PU) pressure-sensitive adhesive (PSA) with high activity and polarity for wide applications. In this work, a novel microcross-linked solvent-free PU adhesive based on a chain extender from glycolysis of waste polyethylene terephthalate (PET) was processed. The adhesive displayed stable adhesion on a variety of substrate materials including steel, plastic, glass, paper, and wood. The adhesive strength on wood substrates can be up to 1.69 MPa, and the 180 peeling strength is 2.75 N/2.5 cm, which is comparable to other PSA made from recyclable resources. The main component of PET glycolysis products (LGOP), bis(2-hydroxyethyl) terephthalate, can cause rapid expansion and cross-linking of the PU chain segment. The PU adhesive demonstrates molecular reconstruction capability, good healing, excellent ductility, and thermal stability due to the presence of the strong polarity and rigid aminoester group and cross-linking. Chang's viscoelastic windows of Chang's PU adhesives shifted to quadrant II under high shear pressures, and quadrant V could be used for general-purpose sensitive adhesives. This study presents an environmentally friendly method for producing PU adhesive by recycling waste PET as a key raw material for pressure-sensitive adhesive.