荧光共轭聚合物单分子膜的制备及其对硝基芳烃的传感性能研究

Fluorescent conjugated polymer have attracted a great deal of attention for their ability to produce signal gain in response to interactions with analytes. This has led to them being referred to as amplifying fluorescent polymers (AFPs), while some researchers have referred to this gain in terms of superquenching. However, sometimes they can't behave so well as expected because of several problems, such as loss of sensory materials, poor permeability,et al.In this work, we will prepare a sensory with novel structure of brush-like monolayer, which will solve most of the above problems.. .The preparation procedures are as following: A strong electron acceptor of triazine is used to induce a kind of mechanism named chain-growth polycondensation, by which a macromolecule of Poly(phenyleneethynylene)fluoren (PPEF), with two groups of triethoxysilanyl at one end, is synthesized. This macromolecule is fixed on the actived glass slide by reacting its triethoxysilanyl groups with hydroxyl groups on the surface of glass. Then a brush-like monolayer of PPEF rooted in the glass comes into being...As a sensor for detecting trace of nitroaromatic compounds, the brush-like monolayer show many advantages over its analogue that is prepared by spin-coating method on the glass. Firstly, the loss of sensory materials will not occur due to the fixing of macromolecules on the glass. Secondly, the character of brush-like monolayer endows a large number of holes between the macromolecules, improving the permeability of sensory material. ..The properties in responds to nitroaromatic compounds in solution and air will be measured.

荧光共轭聚合物传感器具有特殊的分子导线效应，与待测物作用时，会产生"一点接触，多点响应"信号放大效应，尤其适合微痕量物质的检测，是实现实时检测硝基芳烃的一种很有发展前景的传感器。然而由传统的旋涂法制备的聚合物薄膜传感器往往存在着易泄漏、渗透性差等问题。本课题设计的毛刷状的单分子膜传感器可以很好地克服这些问题。 .制备方法：首先合成出一端连有烷氧硅基团的聚对苯撑乙炔基芴(PPEF)，然后通过烷氧硅与玻璃表面上羟基的反应将此共轭聚合物接枝到玻璃片上，形成毛刷状的单分子层结构。.PPEF分子因固定在玻璃表面而不易脱落；毛刷状的结构特点使聚合物分子间存在大量空隙，有利于待测物质与聚合物分子迅速而充分地接触；因而这种独特的传感器结构将充分发挥共轭聚合物所特有的分子导线效应，大大增强传感器对硝基芳烃的响应灵敏度。.本课题拟研究这种新型荧光薄膜传感器的合成方法及其对气相和液相中的硝基芳烃的传感性能。

本项目合成了一种芴基荧光共轭聚合物PPEF，并将其接枝于玻璃片表面，从而获得了一种毛刷状单分子膜传感器。该传感器结构无材料泄漏问题，充分发挥了共轭聚合物所特有的分子导线效应，且比表面无限大，大大增强了传感器对硝基芳烃(NACs)的响应灵敏度。传感器对溶液中DNT的平衡猝灭率92%，溶液中猝灭速率常数Ksv=1.77 ×103 L/mol；对气相中DNT检测限达到10-11 g/mL量级。上述研究基本完成了本项目原计划研究目标。但同时发现该传感器存在2个问题：1）接枝率低，荧光较弱；2）具有严重的光漂泊现象。猝灭-恢复的循环实验20次后，荧光只能恢复到初始荧光的50%左右。. 为了进一步提高检测NACs的传感器性能，又进行了以下研究：. 1）利用氨基、羟基等对NACs的富集作用，制备了2种新型的静电纺丝薄膜传感器。其中，通过氨基改性PS制备的富含氨基的静电纺丝薄膜在150 s内荧光传感器对TNT蒸气（〜10 ppb）的猝灭率达65.4%；将明胶与共轭聚合物传感材料在玻璃表明依次静电纺丝，制成了以明胶层为底层、传感层位于上层的双层静电纺丝薄膜，不仅传感层的通透性增强，而且明胶层含有的大量羟基和氨基，对NACs有富集作用。40min内对DNT猝灭率达70%。该静电纺丝膜具有优异的抗光漂白性能。100 min光照后荧光强度几乎不变。. 2）将荧光传感分子与明胶接枝，该薄膜对DNT和TNT的检测限分别是2.4 × 10-11 g/mL和6.1 × 10-12 g/mL，光漂白性能优越，光照30min后荧光强度几乎无变化。. 3）以咔唑、吡嗪等为核心单元，制备了一系列二维超支化共轭聚合物。这类聚合物表现出了更强的超级猝灭效应,与相对应的线型共轭聚合物相比，Ksv常数几乎都增大了一倍。. 4）以金刚烷、POSS刚性结构为核心，制备了一系列三维的超支化聚合物用作NACs传感材料，这类分子通透性好，如POSS为核心的超支化聚合物对TNT的KSV高达2.83×104M-1，且材料具有很好的光学稳定性、热稳定性能。. 5）向传感分子中引入羟基、酰胺基，制备出水溶性传感材料。对DNT、TNT的检测限分别是7.4 × 10–7 mol/L和1.1 × 10–6 mol/L，可满足地表水中DNT、TNT的检测。