Electropolymerization structural control

Electrochemical polymerization of pyrrole on an SWNT electrode using an aqueous HCl 0.5 M solution as electrolyte, resulted in deposition of a PPy film onto the SWNT layer leading to a composite with a bilayer structure, as demonstrated by Raman spectroscopy [112]. Anew method was developed by S.Cosner eta/, in 2008 [111] SWNTs were functionalized by electropolymerizable pyrrole groups following covalent and noncova-lent strategies. The covalent pyrrole grafting was carried out by ester formation between pyrrole alcohol and chemically oxidized SWNTs. The strong Ti-interactions between pyrene and SWNTs were exploited for the noncovalent adsorption of a new pyrene-pyrrole derivative on the pristine CNT surface. The pyrrole-ester-SWNTs were solubilized in THE and electropolymerized by controlled potential electrolysis at 0.95 V. The PPy/SWNT... 

Most suitable for electrically conducting materials such as carbon fibers, the electrochemical processes involve deposition of polymer coatings on the fiber surface through electrodeposition or electropolymerization techniques. The major advantage of these processes is that a uniform layer of controlled thickness and variable polymer structure and properties can be obtained by controlling the current and the solution concentration. 

As already pointed out above, electropolymerization has many variables which are difficult to control, and thus the structural parameters of the materials obtained tend to be variable. For example, depending on the electrochemical procedures used for the preparation of polythiophene, the conductivity can vary from 0.1 to 1000 S cm-1. This may be due to chain defects, the orientation of chains and the molecular weight the shorter the chain length, then the lower the conductivity is expected to be, since the conjugation is broken. 

The design of subtle specific methods for depositing metal NPs, e.g. [144,145] is another way to control the location of the metal deposit within the CP layer. One proposed approach involves the deposition of a thin, sacrificial Au layer on a Pt substrate, electropolymerization of PANI on the Au-plated substrate, gold oxidation in chloride solution, and finally reduction of the AuCU eomplexes entrapped in the PANI structure. Thus gold/ polyaniline free-standing eomposite films are produced [144,145]. 

Electropolymerization method is one of the most interesting method to control the copolymer composition in molecular sequence or chain sequence, drastically. Accordingly, in the case that the property of the electropolymerized material is electro-conductive and insoluble, a heterolayer structure and/or a sloped structure with conducting polymers are constructed on the electrode. 

Electrodeposition and electropolymerization methods are convenient direct procedures for preparing modifying layers. The thickness and frequently the permeation and charge transport characteristics of the polymer films can be controlled by the applied potential. Lack of knowledge of the precise structure of the electropolymerized or electrodeposited polymer films however represents a problem. 

CP nanomaterials can be synthesized by chemical or electrochemical methods. In chemical reactions generally powdery nanomaterials are produced and can be scaled up. Nanostructures of CP deposited on the electrode surface as films by electropolymerization have limited surfaces compared to the materials obtained by chemical synthesis. Nanostructures generally grow along the direction of the electric field to form oriented structures. The electrochemical polymerization reaction rate can be controlled through the applied potential or current density, and controlled amount of product can also be obtained. The morphology of the nanomaterials may also be modulated by the conditions of electropolymerization. Electrochemical polymerization is an... 

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