Interpenetrating network based polymeric sensors with enhanced specificity, sensitivity, and reusability

Cholesteric liquid crystals (CLCs) are widely used as optical sensors against volatile organic compounds (VOCs), whose sensitivity can be increased with the help of strain. However, the specificity and reusability of these structures should be increased to achieve their successful integration into useful applications. For this purpose, we developed an interpenetrating polymeric network (IPN) based on poly(RM257) structure of CLC-templated polymeric films and polydimethylsiloxane (PDMS). Contrary to the generic CLC-hosted IPN sensors that use CLC structures to optically report the changes in the polymeric matrix, we employed the collaborative responsiveness of the constituents of the IPN (both CLC-templated and penetrated polymeric structures) to improve the sensor performance. The elastic swelling of PDMS structure increased the durability and reusability of the poly(RM257) polymeric sensor upon exposure to even high VOC vapor concentrations up to their saturation. The sensor tests of both poly(RM257) and IPN films were carried out against four different VOC vapors namely toluene, hexane, acetone, ethanol and also water vapor. The results showed that the synergistic swelling of PDMS and poly(RM257) polymeric structures against vapors directly affected the sensor performance in terms of earned specificity and enhanced sensitivity. Moreover, the real-time experiments showed that the measurement accuracy, response, and recovery time of the polymeric sensors were also improved significantly by the development of IPN as compared to their non-IPN counterparts. This study shows a promise towards further engineering of sensors against various applications through detailed design of the constituent polymers against targeted species.