Photonic crystals in biology

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
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