Shape-memory polyurethane elastomer originated from waste PET plastic and their composites with carbon nanotube for sensitive and stretchable strain sensor

Chemical recycling of polyethylene terephthalate (PET) bottles is prospective for reducing waste plastics. The transformation of waste PET into valuable composites in high efficiency still remains a formidable challenge. Here we report the synthesis of polyurethane elastomer (PUE) by using the degraded products from waste PET via one-pot chain extended process. Then, the composites composed of PUE as substrate with carbon nanotubes as fillers are applied in fabricating stretchable strain sensor. The results show that the degraded product was successfully introduced into the polyurethane chains. The PUE chains showed disordered stacking as the degraded product content increased, with the modulus and elongation at break were up to 763.9 %. The composites assembled strain sensors exhibited stable sensing performance and excellent durability after 1000 cycles at 20 % tensile strain. This may supply a path to efficiently recycle waste PET plastic into valuable and functional composites, and even devices.