Enzymatic Synthesis of Polyaniline/Graphite Oxide Nanocomposites
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Enzymatic Synthesis of Polyaniline/Graphite Oxide Nanocomposites
C. Guerrero-Bermea1, S. Sepulveda-Guzman1, R. Cruz-Silva2 1
FIME-CIIDIT Universidad Autónoma de Nuevo León, Monterrey NL, MX
2
Research Center for Exotic Nanocarbons, Shinshu University, Nagano, JP
ABSTRACT In this work, we prepared graphite oxide (GO)/polyaniline nanocomposites by enzymatic polymerization of aniline in an aqueous dispersion of graphite oxide. Two GO dispersions with sheets having an average lateral size of 12.50 µm and 247 nm were used. The enzymatic polymerization was carried out in aqueous acidic medium using toluenesulfonic acid (TSA) as doping agent, horseradish peroxide (HRP) as catalyst, and hydrogen peroxide as oxidizer. The polymerization reaction was studied using 1.0, 2.5 and 5 wt % of GO and nGO dispersions. No changes were observed in the catalytic activity of the peroxidase during the enzymatic synthesis due to the additionof GO sheets. Scanning electron microscopy images show that PANI colloids were attached on GO sheets. The PANI-GO colloids were characterized by ultraviolet–visible spectroscopy and Fourier transformed infrared spectroscopy, whereas their colloidal stability was evaluated at different pHs. The UV-vis spectroscopy study revealed that GO affects the electronic conjugation of PANI modifying its absorption spectrum.
INTRODUCTION In the last 35 years conducting polymers have attracted great interest due to their special characteristics such as light weight, organic functionality, and distinctive electronic behavior [1]. Polyaniline (PANI) [2,3] is among the most interesting conductive polymers due to its chemical stability, tunable conductivity, and interesting electrochromic behavior [7]. This conductive polymer can be successfully synthesized by electrochemical [8], chemical [9], or enzymatic [2] oxidation of aniline. The enzymatic synthesis of PANI is very attractive because the enzyme is biodegradable, non-toxic, energy efficient and obtained from renewable resources [10]. The combination of polyaniline with carbon nanomaterials might improve its electrical and mechanical properties. Wu et al. studied polyaniline/graphite nanosheets composites and found their electrical conductivity improved because the graphite nanosheets built a conductive network within the PANI matrix [11]. Recently, graphene oxide (GO), has gained attention as a graphene precursor. Graphene oxide is electrically insulator with a surface area greater than most carbon nanomaterials, which favors the formation of composites [9]. In addition GO is highly water dispersable. Nevertheless, due to its high aspect ratio, viscosity of GO dispersion is high
even at low concentration. To overcome this issue, the preparation of GO nanosheets has been studied resulting in very stable dispersions [12]. Nanocomposites based on conductive polymers and GO might combine properties from both materials resulting materials with potential application in biological sciences [9], organic electronics [13], sensors [14], actuators [15], separation tec
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