Nano Archive

A water-soluble polythiophene–Au nanoparticle composite for pH sensing

Panda, Biswa Ranjan and Chattopadhyay, Arun (2007) A water-soluble polythiophene–Au nanoparticle composite for pH sensing. Journal of Colloid and Interface Science, 316 (2). pp. 962-967.

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Abstract

In this paper, we report the development of a reversible pH sensor in aqueous medium based on the fluorescence properties of a polythiophene–gold nanoparticle (Au NP) composite. The composite was synthesized in water by simultaneous reduction of HAuCl4 to Au NPs and polymerization of thiophene in the presence of no additional reagents. It was stable for weeks and had characteristic emissions, which changed in the pH range of 3.0 to 6.0, thus providing a mean for probing the pH of an aqueous solution. Measurement of the pH could be performed over several cycles of titrations, pointing to the robustness of the materials for such sensing applications. The mass spectra of the composite at two extreme pH values were identical, indicating that the primary structure of the polymer was not affected due to changes in pH of the medium. Transmission electron microscopic (TEM) measurements indicated the presence of small sized Au NPs with the polymer in the milieu. The composite could be titrated by acid (or base) and considering the acid–base equilibria at different pHs, we have been able to calculate the pKeq of the composite, which was further used in calculating the pH of an aqueous solution from the emission spectrum of the composite. Our approach took advantage of redox chemistry in synthesizing the water-soluble composite and the optical behavior of a conjugated polymer in developing an important pH sensor, which may form the basis of further development of versatile pH or other sensors by suitably modifying the backbone of the monomer.

Item Type:Article
Subjects:Material Science > Nanochemistry
Divisions:Faculty of Engineering, Science and Mathematics > School of Chemistry
ID Code:4360
Deposited By:JNCASR
Deposited On:03 Apr 2009 05:16
Last Modified:03 Apr 2009 05:16

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