NIPAM改性PEDOT:PSS导电聚合物的制备及在电致变色器件中的应用

Preparation of NIPAM modified PEDOT:PSS conductive polymers and its application in electrochromic devices

摘要:

聚3,4-乙烯二氧噻吩:聚苯乙烯磺酸盐(PEDOT:PSS)是一种可分散于水中且导电性较好的聚合物，将其水分散液刮涂至透明薄膜上，可用于制备电致变色器件的离子储存层。但PEDOT:PSS导电薄膜的耐水性和柔韧性较差，限制了其在柔性器件领域的应用。以柔性疏水小分子异丙基丙烯酰胺(NIPAM)对PEDOT:PSS进行共聚改性，制备了具有不同NIPAM摩尔分数的聚[(苯乙烯磺酸盐)-共-异丙基丙烯酰胺]〔P(SS-co-NIPAM)〕，并以其为模板采用氧化聚合法制备了导电聚合物PEDOT:P(SS-co-NIPAM)。相比于未改性的PEDOT:PSS薄膜，添加15%（摩尔分数，以对苯乙烯磺酸钠的物质的量为基准，下同）NIPAM时，薄膜透光率保持在81.1%，水接触角从18.5°增加至39°，疏水性增加，并且弯曲1000次后方阻变化量为5.71 kΩ/sq，方阻变化量远小于未改性的PEDOT:PSS薄膜（10.60 kΩ/sq）。以摩尔分数15% NIPAM的PEDOT:P(SS-co-NIPAM)薄膜作为离子储存层的电致变色器件的光学对比度（ΔT）为9.83%，循环800次后ΔT仍达到9.55%，仅衰减0.28%，衰减量与未改性的PEDOT:PSS器件相当，说明NIPAM共聚改性能改善PEDOT:PSS导电聚合物的柔韧性和疏水性，以其作为离子储存层的器件可维持优异的电致变色性能。

Abstract:

Poly(3, 4-ethylenedioxythiophene):Polystyrene sulfonate (PEDOT:PSS) has good conductivity and can be easily dispersed in water. Coating the aqueous dispersion onto transparent films can be used to form ion storage layers for electrochromic devices (ECDs). However, the poor water resistance and flexibility of PEDOT:PSS conductive films limit their application in the field of flexible devices. In this paper the flexible hydrophobic molecule isopropylacrylamide (NIPAM) was applied to modify PEDOT:PSS. A series of poly ((styrene sulfonate)-co-isopropylacrylamide) P(SS-co-NIPAM) copolymers with different proportions of NIPAM was prepared, and the conductive polymer PEDOT:P(SS-co-NIPAM) was prepared by oxidative polymerization using P(SS-co-NIPAM) as template. Compared with the unmodified PEDOT:PSS film, when 15% NIPAM (molar fraction, based on the substance content of sodium styrene sulfonate) was added, the transmission rate of the film remained at 81.1%, the water contact angle increased from 18.5° to 39°, the hydrophobicity was improved, and after bending of 1000 times the change of square resistance of the film was 5.71 kΩ/sq , which was much smaller than that of the unmodified PEDOT:PSS film (10.60 kΩ/sq).The optical contrast (ΔT) of the electrochromic devices with PEDOT:P(SS-co-NIPAM) containing 15% NIPAM was 9.83%. After 800 cycles, the ΔT was 9.55%, which was decreased only 0.28%, the attenuation was comparable to that of the devices with unmodified PEDOT:PSS films as ion storage layer. The results indicated that NIPAM improved the flexibility and hydrophobicity of PEDOT:PSS conductive polymer, and the ECD devices using PEDOT:P(SS-co-NIPAM) as ion storage layer could maintain excellent electrochromic performance.