A new insight into the mechanism of influence of different inorganic salts on optical properties of water-soluble cationic conjugated polymers

• Published in: Polymer international Vol. 60; no. 10; pp. 1514 - 1520
• Main Authors: Liu, Qianqian, Lü, Xiaodan, Geng, Lei, Lü, Changli
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.10.2011; Wiley
• Subjects: Applied sciences; Cationic; Doppler effect; electrochemical properties; Exact sciences and technology; Inorganic salts; Optical properties; Organic polymers; Physicochemistry of polymers; polycation; Polyelectrolytes; Polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Red shift; Spectra; water-soluble conjugated polymer; polycation; Photoluminescence; Fluorescence; Phenylenevinylene derivative polymer; Experimental study; Polyelectrolyte; Conjugated polymer; Electrochemical properties; inorganic salts; Medium effect; Optical properties; Concentration effect; Counter ion; Quaternary ammonium polymer; water-soluble conjugated polymer
• ISSN: 0959-8103; 1097-0126
• DOI: 10.1002/pi.3110

The water‐soluble conjugated polyelectrolyte poly{2,5‐bis[3‐(N,N,N‐triethylammoniumbromide)‐1‐oxapropyl]‐1,4‐phenylenevinylene} (P2) was synthesized and the influences of different inorganic salts on the optical properties of the polyelectrolyte were studied. New absorption and emission peaks at longer wavelength can be observed in the case of P2 with addition of different concentrations of Cl− or NO3−, whereas addition of I− or ClO4− only induces a red shift. Interestingly, addition of SO42− or F− does not result in considerable changes in optical spectra. Through UV‐visible spectrometry, photoluminescence, 1H NMR and cyclic voltammetry, we showed that the nature of the inorganic salts brings these different changes. The special structure of the $\prod{_{4}}^{6}$ bond of NO3− and the large electronegativity of chlorine lead to an electron transfer between the conjugated polymer and the negative ions. The large radius of I− and the weak electron withdrawing ability of ClO4− only bring a red shift of optical spectra. In addition, SO42− and F− do not affect the spectra significantly, except that the fluorescence intensity falls slightly indicating that P2 is not sensitive to these ions. Copyright © 2011 Society of Chemical Industry The influences and possible mechanism of inorganic salts on the optical properties of P2 were studied. Different nature of the ions induced the changes of the optical behavior of P2.