Implementation of thermo-responsive polymer coatings for an early warning against critical temperature states of thermo-sensitive electronic devices with metal oxide (MOx) gas sensors

Abstract

Thermo-sensitive electronic devices such as Li-ion battery systems have reached a tremendous importance over the past years, in particular due to the increased pace of technology developments in the sector of e-mobility. In the present study, thermo-responsive functional coatings which release volatile cleavage products at well-defined temperatures were developed towards their use for indirect detection of critical temperatures by metal oxide (MOx) sensors. 1,1′-Azobis(cyclohexanecarbonitrile) (ABCN) and 2,2′-azodi(isobutyronitrile) (AIBN) were implemented as additives with a concentration of 4.7 wt% in polyurethane coating formulations. The thermolysis of the blowing agents and release of tracer gases were studied by differential scanning calorimetry, thermogravimetric analysis and evolved gas analysis coupled with mass spectrometry, showing comparable peak temperatures of gas release and no significant impact of the polyurethane matrix on gas release. In addition, the released gases could be successfully monitored by implementing MOx gas sensors in combination with effective algorithms to compute a warning signal in real-time with high robustness against false positives. This work therefore paves the way towards functional coatings, which have the ability to trace critical temperatures and hot spots of sensitive electronic-based systems on large and non-conformal surfaces by indirect measurements through low-cost MOx gas sensors.