Design of healable, porous polyurethane with large ionic liquids loading amounts towards ultra-durable pressure sensor

Abstract

Flexible intelligent sensors have got booming development over the past decades, yet, it is still a huge challenge to construct advanced sensors with long service life and superb durability. Herein, a novel porous capacitance pressure sensor with ultra-durability via sugar template method was prepared successfully by impregnating non-volatile, highly conductive ionic liquids (ILs) into polyurethane (PU-DBTDA5) matrix. As a consequence of the rich hydrogen bonding networks and dynamic hindered urea bond in the polymer chain, the as-prepared PU-DBTDA5 matrix shows excellent self-healing ability (99 %). The ionic liquid-soluble polyethylene glycol (PEG1000) serving as soft segment endows PU-DBTDA5 with ultra-absorption ability of ILs (absorbing ILs over three times to its own weight within 5 min). The pressure sensor with porous structure shows outstanding anti-fatigue ability as well as good sensitivity (S1 = 0.82 kPa−1, S2 = 1.04 kPa−1), and it can even monitor tiny strain as low as 0.5 %. More importantly, due to the well combination of the PU-DBTDA5 with excellent self-healing ability and the non-volatile ionic liquids, not only the healed sensor, but the sensor stored at room environment over 100 days both exhibit stable electronic signals similar to that of freshly-prepared foam sensor in 3000 uninterrupted compression tests, being strong evidence of its ultra-durability.