UV曝光對聚苯乙烯-聚苯胺核殼型態導電薄膜導電率熱穩定性之影響

Abstract

本研究之目的在於探討核殼型態聚苯乙烯-聚苯胺導電薄膜暴露於UV環境下對導電率的影響，並進一步瞭解經UV曝光後薄膜於高溫環境下導電率劣化情形以及導電薄膜電子傳導模式。 以無乳化聚合方式合成聚苯乙烯乳膠粒子，並在其表面包覆一層聚苯胺形成核殼型態導電粒子，並利用聚苯乙烯-聚苯胺核殼乳膠粒子以加熱至高於核心玻璃轉移溫度的方式製備導電薄膜。導電薄膜經過UV曝光之後其導電率並無太大的變化，而在添加光起始劑的情況下，曝光後的薄膜導電率則顯著地降低。探討未曝光、曝光後以及加光起始劑曝光後導電薄膜於氮氣及空氣環境下高溫劣化情形，以加光起始劑曝光後的導電薄膜因曝光而產生的交聯結構使其具有較佳的熱穩定性。最後藉由導電薄膜之導電率與劣化時間、量測溫度之關係，無論是未曝光、曝光後以及加光起始劑曝光後之導電薄膜，均符合σ/σ0＝exp[-(T0/T)0.5]，其傳導模式類似於粒狀金屬之跳躍傳導(hopping)，經過UV曝光對薄膜的導電機制並無影響。

The purpose of the study is to discuss the effect of UV irradiation on the conductivity of conductive films based on polystyrene(PS)-polyaniline (PANI) core-shell latexes. Furthermore, conduction mechanism and aging effect on conductivity of conductive films after UV irradiation were investigated. The PS-PANI core-shell latexes were synthesized; conductive films were made by casting and heating the PS-PANI core-shell latex particles above the glass transition temperature of polystyrene. After exposure to UV irradiation, the conductivity of conductive films decreased slightly. In contrast, the conductivity decreased obviously after UV irradiation when photoinitiator was added to the PS-PANI film. The aging effect on conductivity of conductive films in different atmosphere was investigated. Among three types of conductive films (unexposed, exposed, and exposed with photoinitiator), the exposed conductive film with photoinitiator has the best thermal stability due to crosslinked structures formed during UV irradiation. Moreover, for all the conductive films, the temperature dependence of conductivity follows the law: σ/σ0＝exp[-(T0/T)0.5]. It indicated the conduction proceeds through hopping between small conducting grains separated by insulating barriers.