Khatun Rijia, Majhi Koushik, Meriga Venkanna, Chakraborty Amit K, Sinha Subrata
Integrated Science Education and Research Centre, Siksha Bhavana , Visva-Bharati , Santiniketan 731 235 , India.
Carbon Nanotechnology Laboratory, Department of Physics , National Institute of Technology Durgapur , M. G. Avenue , Durgapur 713 209 , India.
J Phys Chem A. 2018 Sep 6;122(35):7089-7098. doi: 10.1021/acs.jpca.8b06640. Epub 2018 Aug 23.
Sulfonated polyaniline (SPANI) has emerged as a promising polymer in the past few decades due to its solubility in water and relatively moderate conductivity. However, to date, literature data on the optical characterization of SPANI are very limited and preliminary in nature. In the present work, SPANI is synthesized by direct sulfonation of emeraldine salt form of polyaniline with chlorosulfonic acid in an inert solvent. Detail photophysical properties of SPANI are investigated in aqueous medium by using steady state (concentration, temperature, pH, and excitation wavelength dependence) and time-resolved spectroscopic techniques. The steady state fluorescence emission measurements are carried out carefully to avoid inner filter effect (especially secondary inner filter effect or reabsorption effect) as well as scattering. Two ground state conformations of SPANI are suggested to exist in aqueous medium. Excitation wavelength dependence of the fluorescence emission spectra is attributed to red-edge effect. All these observations are nicely corroborated by the fluorescence lifetime data of SPANI obtained from time-resolved measurements. All these new findings are extremely important in view of the potential applications of SPANI in polymer optoelectronics.
在过去几十年中，磺化聚苯胺（SPANI）因其在水中的溶解性和相对适中的导电性而成为一种很有前景的聚合物。然而，迄今为止，关于SPANI光学特性的文献数据非常有限且本质上较为初步。在本工作中，通过在惰性溶剂中用氯磺酸对聚苯胺的翡翠盐形式进行直接磺化来合成SPANI。利用稳态（浓度、温度、pH值和激发波长依赖性）和时间分辨光谱技术在水介质中研究了SPANI的详细光物理性质。为避免内滤效应（特别是二次内滤效应或重吸收效应）以及散射，仔细进行了稳态荧光发射测量。有人提出在水介质中存在SPANI的两种基态构象。荧光发射光谱的激发波长依赖性归因于红边效应。从时间分辨测量获得的SPANI荧光寿命数据很好地证实了所有这些观察结果。鉴于SPANI在聚合物光电子学中的潜在应用，所有这些新发现都极其重要。
