Nanoporous films of polydiacetylenes for visual sensing of volatile organic compounds

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Many volatile organic compounds (VOCs) are harmful to human health and the environment. Simple and efficient methods are urgently needed to detect and discriminate various low-concentration VOCs in air. Polydiacetylenes are promising sensing materials for VOCs because their color can change by exposure to VOCs which can easily be observed. Crucial problems in the development of polydiacetylene-based VOC sensors are: A long response time due to the slow diffusion of VOCs in polydiacetylene films and unsufficiently known relationships between chemical structures and their colorimetric responses to VOCs. To solve the problem of long response time, I plan to develop nanoporous films of polydiacetylenes to quickly detect and discriminate various VOC vapors. To overcome the slow diffusion, we will synthesize block copolymers consisting of a diacetylene-containing block, a poly(ethylene oxide) block and a cleavable junction between the two blocks. Nanoporous polydiacetylene sensor films will be prepared by microphase separation of the block copolymers, removal of the poly(ethylene oxide) block and subsequent photopolymerization of the diacetylene-containing block. We expect that the nanoporosity of polydiacetylene films facilitates the penetration and accumulation of VOC molecules, which speeds up the detection of VOCs. We will vary the morphology of nanoporous polydiacetylene films by chemical modifications and study its impact on sensitivity and response time of VOC detection. To improve understanding of relationships between chemical structures of polydiacetylenes and their colorimetric response to VOCs, I plan to compare colorimetric response of different polydiacetylenes with theoretically predicted color changes. Improved basic understanding of such structure-property relations will enable polydiacetylene sensor arrays with good selectivity to different VOCs which are suitable for visual detection.