化学氧化法制备条件对聚噻吩导电性能的影响

摘要

Polythiophenes were prepared by chemical oxidative polymerization under the conditions of different reaction time t (1 ～ 12 h),temperature θ (-32～0 ℃),molar ratio of oxidant to thiophene n(FeCl3)/n(Th) =2～5,thiophene concentration c (Th) =0.05 ～ 0.20 mol/L.The structure and conductivity of the polythiophenes were characterized using Fourier transform infrared spectroscopy,ultraviolet and visible diffuse reflectance spectroscopy and megohmmeter.The results indicate that these preparation conditions could greatly affect the structure and conductivity of polythiophenes.The conductivity of polythiophene increase from 10-13 to 10-8 S/m with the increase of thiophene concentration from 0.05 to 0.20 mol/L.The highest conductivity of polythiophene at different reaction time is 10-10 S/m when the reaction time is 3 h.The conductivity of the polythiophenes prepared at different temperatures is all at 10-13 S/m level.When the n (FeCl3)/n(Th)increases from 2 to 5,the conductivity of samples increases from 10-13 to 10-10 S/m.The conductivity of the sample prepared by the treatment of direct filtration and washing increases 5 orders of magnitude over that prepared by the treatment of solvent volatilization at room temperature followed by filtration and washing.From the aspect of the balance of conductivity and cost,the optimized reaction conditions are:c(Th)=0.1 mol/L,t=3 h,θ =0 ℃,n(FeCl3)/n(Th) =2,and using direct filtration treatment on the products.Moreover,the optimized conductivity of the polythiophene is 2.49 × 10-8 S/m.%采用化学氧化聚合法,以氯仿为溶剂、无水氯化铁为氧化剂,制得了聚噻吩样品,使用傅里叶变换红外光谱仪、紫外可见漫反射光谱仪和高阻计对样品结构和电导率进行了分析测试,考察了噻吩浓度(0.05～0.20 mol/L)、反应时间(1～12 h)、反应温度(-32～0℃)、氧化剂与噻吩摩尔比(2～5)、后处理方式对聚噻吩样品电导率的影响.研究表明:上述条件均会影响聚噻吩的聚合程度和连接方式,进而影响其电导率.当噻吩浓度由0.05 mol/L增至0.20 mol/L时,样品电导率从10-13 S/m降至10-8 S/m;反应时间为3h所得样品的电导率最大,为10-10 S/m;当反应温度在0～-32℃时,其电导率均在10-13 S/m数量级;氧化剂与噻吩摩尔比n(FeCl3)/n(Th)的增大会使其电导率增加(10-13～10-10 S/m);反应结束后直接对反应物进行过滤洗涤得到的样品比室温挥发完溶剂再洗涤得到样品的电导率高五个数量级.综合聚噻吩的电导率和原料成本,选定噻吩浓度为0.10 mol/L、反应时间为3h、反应温度为0℃、n(FeCl3)/n(Th)=2,对反应物直接过滤洗涤为最佳制备条件,该条件下所得聚噻吩样品的电导率高达2.49×10-8 S/m.