Self-healing waterborne polyurethane originated from waste PET and their composites with polypyrrole for stretchable strain sensor

Recycled waste plastics and their derivatives serve as crucial alternatives to traditional petroleum-based materials, offering a sustainable strategy for mitigating environmental pollution. In this work, we prepared waterborne polyurethane (WPU) with enhanced transparency, heat resistance, and mechanical properties by using the depolymerisation products (GOPs) as a chain extender from waste polyethylene terephthalate (PET) bottles. Additionally, we incorporate dihydroxyethyl disulfide (HEDS) with GOPs co-chain extender imparts significant self-healing capabilities, with strain and tensile strength healing rates of up to 82.57% and 93.72%, respectively. Furthermore, a composite membrane featuring a polypyrrole (PPy) core was further fabricated for flexible strain sensors, which demonstrated excellent dynamic responsiveness, signal stability, and electrical monitoring performance. These findings underscore the promising potential of upcycled waste plastics in the development of advanced materials for flexible electronics and packaging applications.