Poly (N-isopropylacrylamide) (pNIPAm) is an extensively studied thermoresponsive material that transitions from fully soluble (swollen) in water at a temperature below 32 °C, to a desolvated globular (deswollen) state above 32 °C; the transition is fully reversible and can be repeated many times. We showed that optical devices, called etalons, could be generated by sandwiching pNIPAm-based hydrogel particles (microgels) between two thin gold layers. The structure of the device affords it color, which could be tuned by changing the thickness of the pNIPAm microgel-based layer. Here, we show that the thickness of the pNIPAm microgel-based layer (and the etalon color) could be varied upon exposure to various volatile organic compound (VOC) vapors such as: hexane, cyclohexane, chloroform, petroleum ether and tetrahydrofuran (THF). We conducted a thorough investigation of the response of the etalons to the different VOCs, and found that the devices were most sensitive to THF vapor, exhibiting a fast response time (4 mins) with a limit of detection of 1.27 mM. We also show that the devices can be reused multiple times for VOC analysis without a loss in device performance.  <br/>

Layered polymer-based devices for detecting volatile organic compounds

2019 Fall National Meeting

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