Polysiloxane-containing non-isocyanate polyurethane: From soybean oil and CO2-based compound to flexible sensors designed for availability in a wide temperature range

Abstract

Flexible sensors have been widely developed in recent years with the growing popularity of the Internet of Things, resulting in a large amount of electronic waste that poses potential environmental problems. Due to the increasing concern about environment, the use of biomass resources to prepare environmentally friendly and recyclable materials is of significant research interest. Meanwhile, self-healing, sensitive monitoring of signal changes, and the ability to be used in extreme environments are also critical features of flexible sensors. Herein, a bio-based conductive non-isocyanate polyurethane (NIPU) was obtained by the reaction of carbonated soybean oil (CSBO) with polyaminopropylmethylsiloxane (PAPMS). And carbon black (CB) was introduced as a conductive filler. The mechanical properties and electrical conductivity of the NIPU were adjusted by changing the molar ratio of amino to cyclic carbonate and adding CB. The prepared NIPU can show excellent thermal stability, solvent resistance, tensile properties, and self-healing ability (above 90% healing rate). In addition, due to the flexible segment of siloxane in the network, NIPU can exhibit high tensile strain (> 400%) at extremely low temperatures (−40 °C) without being destroyed, and the actions of volunteers can be sensed and converted into sensitive and stable electrical signals over a wide temperature range (−40 to 60 °C). The highly elastic NIPU sensor displays great promise for applications in wearable electronics in harsh environments.