Synthesis of Poly(ether carbonate)-Based Polyurethane for Biodegradable–Recyclable Pressure Sensors

Developing biodegradable and recyclable pressure sensors is quite important to broaden their application fields and reduce adverse environmental impact. However, the relevant research in this area is still limited. In this work, a biodegradable and recyclable pressure sensor was proposed by employing biodegradable polyurethanes. The poly(ether carbonate) diol (PEC) with 40% biodegradable groups (carbonate groups) was polymerized with isophorone diisocyanate and butane-1,4-diol to produce a biodegradable PEC-based polyurethane (BPPU) (Mn = 5.89 × 104 g/mol). Structural analysis of the products was conducted by 1H NMR and FTIR spectroscopy. The DSC results indicated that the glass-transition temperature of BPPU was −24 °C. In particular, the obtained BPPU showed an excellent biodegradation rate in the soil compared to previously reported polyurethanes, with 72.88% degradation in 103 days. BPPU working as the substrate of a pressure sensor presented high sensitivity (S = 41.29 kPa–1), a wide response range (0.62–62.5 kPa), and good durability (6250 cycles). The sensor displayed not only the capability to detect signals of human breathing, joint movements, and writing but also the recyclability of silver interdigital electrodes. At present, the synthesized BPPU shows broad application prospects in flexible sensors with promising low-temperature resistance, biodegradability, and flexibility.