水性磺酸型聚氨酯/聚吡咯导电材料的制备、微观结构及成膜机理

摘要

以2,4-二氨基苯磺酸钠为亲水扩链剂,通过预聚体法合成了水性磺酸盐型聚氨酯分散液(SW-PU).并在FeCl3氧化剂的作用下,采用原位化学氧化聚合法制备了系列不同聚吡咯(PPy)质量浓度的水性聚氨酯/聚吡咯(SWPU/PPy)分散液,并通过溶液浇铸法制得系列复合导电薄膜.随着 PPy 的引入, SWPU分子与 PPy 分子间发生反应,SWPU/PPy 的高温热稳定性亦得到提高.随着吡咯质量浓度的增加,SWPU/PPy乳胶粒的粒径增加.经适量PPy改性后,PPy可在SWPU 胶束内部和表面均匀分布,形成大小均匀的纳米复合粒子；SWPU/PPy复合膜表面粗糙度下降,SWPU与PPy间具有较好的相容性.但当PPy质量浓度高于15％时,开始呈现一定的颗粒形貌,且薄膜表面粗糙度随着 PPy 浓度的增加明显增加；当PPy质量浓度高于30％时,胶膜表面颗粒形貌明显,胶膜表面主要由 PPy 组成.复合薄膜的渗透阈值介于质量浓度为1．5％~2％之间,当Py质量浓度为30％时,电导率高达1 S/cm.%Waterborne sulfonate polyurethane dispersion (SWPU ) was prepared through prepolymerization method with 2,4-diamino-benzene sulfonic acid sodium salt (DASS)as hydrophilic chain extender.Then with the assistant of FeCl3 oxidant,SWPU/polypyrrole (SWPU/PPy)dispersions with different mass concentration of polypyrrole (PPy)were prepared by in situ chemical oxidative polymerization,and the corresponding conduc-tive composite films were obtained by solution casting method.With the introduction of PPy,new urea bond was formed through the reaction between SWPU and PPy.The high-temperature thermal stability was also im-proved.With the increase of pyrrole content,the average particle size of SWPU/PPy dispersions increased.Sig-nificant aggregation was detected among SWPU colloidal particles,and the SWPU/PPy particles disperse well. With the addition of certain amount of PPy,PPy was able to distribute uniformly across SWPU colloidal parti-cles,and homogeneous nanocomposites were therefore formed;in addition,the surface roughness decreased, and good compatibility between SWPU and PPy was detected.However,particular morphology appeared when the mass concentration of PPy was higher than 1 5%,and surface roughness increased with increasing the mass concentration of PPy.Particular morphology became apparent when the mass concentration of PPy was 30%, the surface of SWPU/PPy was mainly composed of PPy.The percolation threshold of SWPU/PPy films was in the range of 1.5%-2%,and the surface conductivity reached 1 S/cm when PPy content was 30%.