The blue thin polyaniline base film changes its color to green after immersion of the film into dibutyl phosphonate. The green color of the film converts to a greenish-blue after heating to 200 °C in air, which is characteristic for the protonated conducting form of polyaniline. This is in contrast to the “standard” polyaniline hydrochloride, which is transformed into a cross-linked polyaniline base under such conditions. To explain this unexpected observation, the interaction of polyaniline base with dibutyl phosphonate at ambient conditions and after heating to 200 °C was studied using UV–visible, FTIR and Raman spectroscopies. On the basis of these studies, we propose that the dibutyl phosphite tautomeric form of dibutyl phosphonate, which interacts with polyaniline base at 20 °C, converts to the oxidized form, dibutyl phosphate, at 200 °C and subsequently protonates the film. Quantum-chemical modeling of the interaction of polyaniline base with dibutyl phosphite and dibutyl phosphate supports this explanation.

中文翻译：

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亚磷酸二丁酯转化为磷酸酯对聚苯胺薄膜的热诱导质子化作用

将薄膜浸入膦酸二丁酯后，蓝色的薄聚苯胺薄膜变色为绿色。在空气中加热到200°C后，薄膜的绿色转换为绿蓝色，这是聚苯胺的质子化导电形式的特征。这与“标准”聚苯胺盐酸盐相反，后者在这种条件下转化为交联的聚苯胺碱。为了解释这一意想不到的发现，使用紫外可见光，FTIR和拉曼光谱研究了在环境条件下以及加热至200°C后聚苯胺碱与膦酸二丁酯的相互作用。根据这些研究，我们建议在20°C下与聚苯胺碱相互作用的亚磷酸二丁酯的亚磷酸二丁酯互变异构形式转化为氧化形式，磷酸二丁酯，在200°C的温度下，随后使薄膜质子化。聚苯胺碱与亚磷酸二丁酯和磷酸二丁酯相互作用的量子化学模型支持了这一解释。