Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 Investigation of nucleation and growth mechanism during formation of poly(azure A) Emrah Kalyoncu, Kader Dacı, brahim Hakkı Kaplan, Ezgi Topçu, Murat Alanyalıolu* Department of Chemistry, Sciences Faculty, Atatürk University, Erzurum 25240, Turkey Abstract—Nucleation and growth mechanism during formation of poly(AA) films on gold substrates was intestigated. Repeated potential cycling by using cyclic voltammetry and potential controlled electrolysis techniques have been performed to synthesize poly(AA) thin films on gold working electrodes in the solution containing 0.1 mM AA and 0.1 M phosphate solution (pH:6.2). Chronoamperometry, STM (Scanning Tunneling Microscopy), AFM (Atomic Force Microscopy), and UV-vis. absorption spectroscopy techniques were applied for the characterization of prepared polymeric films. Dye polymer films show excellent catalytic and photoelectrochemical properties and have been applied for batteries and electrodes, electrochromic devices, light emitting diodes, and immobilizitaion of enzymes [1,2]. Dye polymer films must have a well-ordered surface to be used in these technological applications. Electropolymerization is one of the simple and useful method to obtain dye polymer films. In the electropolymerization process, deposition of polymeric dye film on the electrode surface is achieved by constant or cycled potential oxidation of a dye-containing solution. Azure A is a derivative of phenothiazine dye material (Figure 1). for progressive case. Growth of nuclei is slow for instantaneous nucleation and fast for progressive nucleation [7,8]. According to Li and Albery [9], two possible mechanisms are possible for polymer films: Progressive twodimensional layer-by-layer nucleation and instantaneous threedimensional nucleation and growth. In this study, chronoamperometry data (Figure 2) that is obtained during potential controlled electrolysis has been compared with theoretical data to determine the nucleation and growth mechanism of poly(AA). . Figure 1. Chemical structure of azure A The redox behaviour of dyes has been under study for nearly 65 years [3-7]. Chen et al. [6] prepared poly(AA) films in different pH’s and found that the optimum pH of the electrolysis solution is 6.0. It is known that the film growth of polymeric films of dyes is related to the upper potential limit besides pH value of the solution [4,5]. In this study, we have investigated nucleation and growth mechanism during the formation of poly(AA) films on gold substrates. Repeated potential cycling by using cyclic voltammetry and potential controlled electrolysis techniques have been performed to synthesize the thin films of poly(AA) on gold working electrodes. In all cases, an Ag/AgCl (3M NaCl) electrode served as reference electrode, and a Pt wire electrode was used as counter electrode. In the solution containing 0.1 mM AA and 0.1 M phosphate solution (pH:6.2), the potential of working electrode was kept at different upper potential limit of 0,90, 0.95, and 1.00 V. We have investigated nucleation and growth mechanism of poly(AA) film by using chronoamperometry technique. Nucleation and growth term can be described as either instantaneous or progressive. The current densities for these two cases are 2 J ins = at exp( −bt) for the instantaneous case and 2 3 = ct exp( −dt) J prog Figure 2. Experimental current-time transients for different electrooxidation potential values. The non-faradaic charging currents in the absense of AA have been subtracted from these data STM (Scanning Tunneling Microscopy), and AFM (Atomic Force Microscopy) techniques was applied to investigate poly(AA) film surface structure. We have also studied the optical properties of the prepared polymeric films by using UV-vis. absorption spectroscopy. This work was partially supported by Atatürk University under Project No. BAP-2009/245. * Corresponding author: malanya@atauni.edu.tr [1] K. Naoi, H. Sakai, S. Ogano, J. Power Sources 20, 237 (1987) [2] G. Yu, J. Gao, J. C. Hummelen, F. Wudl, A. J. Heeger, Science 270, 1789 (1995) [3] R. Brdicka, Z. Elektrochem. 48, 278 (1942) [4] A. A. Karyakin, A. K. Strakhova, E. E. Karyakina, S. D. Varfolomeyev, A. K. Yatsimirsky, Bioelectrochem. Bioenergetics 32, 35 (1993) [5] J. Liu, S. Mu, Synthetic Metals 107, 159 (1999) [6] C. Chen, S. Mu J. Appl. Polym. Sci. 88, 1218 (2003) [7] M. Alanyalioglu, M. Arik, J. Appl. Polym. Sci. 111, 94 (2009) [8] A. Bewick, M. Fleiscmann, H. R. Thirsk, H. R. Trans Faraday Soc. 58, 2200 (1962) [9] F. Li, W. Albery, J. Electrochim Acta 37, 393 (1992) 6th Nanoscience and Nanotechnology Conference, zmir, 2010 250
Poster Session, Tuesday, June 15 Theme A1 - B702 6th Nanoscience and Nanotechnology Conference, zmir, 2010 251
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