Nanoporous films of polydiacetylenes for visual sensing of volatile organic compounds

许多挥发性有机化合物(VOCs)对人类健康和环境有害。迫切需要一种简单有效的方法来检测和区分空气中各种低浓度的VOCs。聚二乙炔是一种很有前途的VOCs传感材料，因为它们的颜色可以通过暴露在VOCs中而改变，这很容易观察到。发展基于聚二乙炔的VOC传感器的关键问题是：由于VOCs在聚二乙炔薄膜中的缓慢扩散而导致响应时间较长，以及化学结构与其对VOCs的比色响应之间的关系还不够清楚。为了解决响应时间长的问题，我计划开发聚二乙炔纳米孔膜，以快速检测和区分各种VOC蒸气。为了克服缓慢的扩散，我们将合成嵌段共聚物，它由一个含有二乙炔的嵌段、一个聚氧乙烷嵌段和两个嵌段之间的可切割连接组成。通过嵌段共聚物的微相分离、聚氧乙烷嵌段的去除以及随后的含二乙炔嵌段的光聚合，可以制备纳米多孔聚二乙炔传感器薄膜。我们预计，聚二乙炔薄膜的纳米级有助于VOC分子的渗透和积累，从而加快VOCs的检测速度。我们将通过化学修饰来改变纳米多孔聚二乙炔薄膜的形貌，并研究其对VOC检测灵敏度和响应时间的影响。为了更好地了解聚二乙炔的化学结构与其对VOCs的比色响应之间的关系，我计划比较不同聚二乙炔的比色响应与理论预测的颜色变化。提高对这种结构-性质关系的基本了解将使聚二乙炔传感器阵列对适合于视觉检测的不同VOCs具有良好的选择性。

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.