Valorization of waste plastics to prepare tough, stretchable and highly conductive ionicgels

Abstract

Polyethylene terephthalate (PET) is one of the most widely used polymers, and its intensive use has resulted in significant and growing environmental problems. The urgent need for a more efficient approach that avoids the cumbersome depolymerisation process and monomer purification to produce high-value products is evident. In this study, a simple and one-pot strategy was used to obtain polyurethane pre-polymer through the glycolysis of PET. The polyurethane network and the second polymer network formed by the monomers polyacrylic acid and polyacrylamide were co-introduced into the ionicgels to create a dual network structure. Glycolysis of PET was catalyzed using the ionic liquid catalyst [EMIM][DCA], resulting in a 100 % conversion. The PET alcoholysis solution consisted of 90.47 % BHET, 9.53 % oligomers containing benzene rings, and unreacted glycol. Polyurethanes synthesized through the one-pot method using PET hydrolysate, with benzene ring-containing BHETs and oligomers as the hard domains and ethylene glycol as the soft domains, exhibited excellent mechanical properties. PET-based polyurethane was employed in the preparation of dual network-structured ionicgels. As a result, the ionic gels exhibited a good stress–strain of 4.2 MPa and 990 %, along with a high conductivity (0.09 S/cm) and ultrahigh sensitivity. Furthermore, it could easily repair the broken ionicgels at 25 ℃ for 6 h, thus restoring their original tensile, and sensing properties.