Conductive surface via graft polymerization of aniline on a modified glass surface
Introduction
Owing to its unique electro-optical properties, polyaniline (PANI) has been extensively investigated in the field of conductive polymers [1]. Among the research directions, the chemical deposition of PANI as a thin layer on various materials, such as plastics, glass, metals, as well as on micro- and nano-porous materials generated a new area of applications [2]. The coating of various materials with a layer of conductive polymer was achieved by using several methods, such as the spreading of a solution of conductive polymer on the surface of the material followed by the evaporation of the solvent, the electropolymerization of the monomers on an electrode, or the chemical polymerization and deposition on the surfaces of various materials immersed in the polymerization solution.
In recent years, a great deal of attention was paid to coating the surface of glass and related inorganic substrates with a layer of conductive polymers to prepare electrochromic displays, liquid crystal displays and “smart windows” [3]. On a smooth surface of glass, the adhesion of a conductive polymer is usually poor. The increase of the surface adhesion was achieved through a chemical pre-treatment, by spraying SOCl2 on the surface of glass at 400 °C, thus binding Cl to the glass surface; this was followed by the grafting of a polymer [3]. This method generated a strong chemical bond between glass and PANI. Some attempts have been also made to generate a self assembly (SAM) monolayer or a patterned SAM monolayer, using an alkoxysilane containing an aniline or a pyrrole group, followed by the physical, chemical or electrochemical deposition of conductive PANI or polypyrrol [4], [5], [6], [7]. However, the above SAM methods provided incomplete coverage, and there were even difficulties in the preparation and purification of the silane compounds bearing an aniline or a pyrrole group [8], [9].
In this paper, we employed the aniline monomer substitution reaction on a SAM silane monolayer, followed by the grafting of PANI on the surface. The method involves the initial formation of a stable silane monolayer through its reaction with the hydroxyl groups of the glass surface. This was followed by the functionalization of the SAM monolayer through aniline substitution, and further, by the surface oxidative graft polymerization of aniline on the modified glass surface via the covalently immobilized aniline sites. This method offers the advantage that one can select a suitable silane coupling agent which can yield a homogenous, reproducible, stable monolayer, using only commercially available, high purity reagents, that are free of the side reactions [9], [10] encountered with other more exotic silane monolayers. Furthermore, the method can be used for SAM monolayers that can be photo-patterned with high resolution, thus, allowing the patterning with conductive polymers after the photolithographic process.
Section snippets
Materials
The microscopic glass slides were purchased from Aldrich/Sigma Chemical Co., and were sliced into rectangular strips of about cm in size. Aniline monomers, 3-bromopropyltrichlorosilane, ammonium persulfate and hydrazine were obtained also from Aldrich/Sigma and were used as received. The anhydrous toluene was dried over 4 Å molecular sieves prior to use. The solvents, such as acetone, ethanol, and N-methylpyrrolidinone (NMP), and other chemicals were of reagent grade and were also
Results and discussion
The strategy for the PANI functionalization of glass hydroxyl-terminated surfaces consists of three basic steps, depicted in Scheme 1: (1) the formation of a well-defined SAM through the reaction of 3-bromopropyltrichlorosilane with the hydroxyls of the glass surface; (2) the debromolization of this monolayer by substitution with aniline, resulting in the formation of an aniline-glass substrate; and (3) the reaction of the aniline sites with an aniline-oxidant solution to produce the desired
Conclusion
A SAM of a 3-bromopropylsilane monolayer can be formed under an inert atmosphere on a glass substrate by the reaction between 3-bromopropyltrichlorosilane and the hydroxyl groups of the surface. It can be further functionalized by the substitution of the brom atoms at the end of silane chains with aniline molecules. The aniline molecules chemically tethered to the glass surface can act as active sites for surface grafting of PANI. The microstructure of the aniline monolayer and grafted PANI
References (19)
- et al.
Synth. Met.
(1990) Polymer
(2001)- et al.
Synth. Met.
(1996) - et al.
J. Electroanalytical Chem.
(2000) - et al.
Synth. Met.
(1997) - et al.
Chem. Mater.
(1998) - et al.
Chem. Mater.
(1997) - et al.
Langmuir
(1997) Chem. Rev.
(1996)
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Application of polyaniline and multiwalled carbon nanotube magnetic composites for removal of Pb(II)
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