Electroless deposition of polyaniline: synthesis and characterization

Abstract

Polyaniline (PANi), as conductive polymer, constitutes an attractive material for electronic and optical applications. Different from electropolymerization and chemical oxidative polymerization, electroless deposition is another method for synthesizing PANi. Aniline can polymerize slowly and spontaneously on platinum or palladium surface in an aqueous acid solution of the monomer. This reaction proceeds via an electrochemical mechanism that involves the reduction of dissolved oxygen as cathodic and oxidation of aniline as anodic half-reactions at the metal/solution interface. PANi, obtained by electroless synthesis, was compared to chemical oxidative and electropolymerized ones by XPS and SEM. The product of electroless deposition is found to be chemically similar to the others but its morphology is different. The PANi film growth and morphology are studied as a function of time and temperature.

Femtogram‐Controlled Synthesis and Self‐Aligned Fabrication of Polyaniline Micro‐ and Nanostructures

“…The method is also known as electroless polymerization 15. This approach is rather poorly studied and has been limited to the use of bulk or thin‐film catalyst coatings to investigate the physicochemistry of the growth16 and more recently to the fabrication of PANI composites with 3D structural control 17. Herein, we develop a device‐oriented process, via miniaturized polymerization reactors, to manipulate and integrate minute quantities of PANI.…”

Technological and Material Related Challenges for Large Area, High Aspect-Ratio, Near Teradot/Inch<SUP>2</SUP> Areal Density and Three-Dimensional Structuring of Polyaniline

“…This behavior is explained by the dissolution of the oxygen from the aqueous media upon heating and hence, the reaction slows down. 23 It has been also reported that the thickness of platinum has an influence upon the polymerization rate. 25 Other key parameters in the aniline electroless polymerization are the catalyst surface cleanliness and reactivity.…”

“…[23][24][25] In electroless polymerization, aniline molecules are oxidized to polyaniline by soluble oxygen on a platinum or palladium substrate (in a first approximation; as it will be shown further the polymerization is not limited only to these substrates). The reaction is initiated by catalysis of the substrate and proceeds continuously with presumably the autocatalysis of the polyaniline film being deposited.…”

Nanowire-templated microelectrodes for high-sensitivity pH detection

“…[9][10][11] The choice of PANI is motivated by its electrochemical properties that are strongly affected by the proton doping and/or the redox activity that take place during immersing in an analyzing environment. [12][13][14] Pt facilitates the PANI polymerization, [15][16][17] acts as an oxidation barrier during the electrochemical synthesis of the template, and not in the least has the necessary electrical properties for the entire fabrication process and measurements. We highlight the advantages of using vertically aligned NWs on top of micro-IDEs.…”

“…At the end, PANI layers of 5-30 nm are polymerized on the entire active surface of the structures by an electroless synthesis, with the Pt NWs brush structure acting as catalyst. The process was performed in an oxygen-saturated solution of aniline ͑0.4 M͒ and H 2 SO 4 ͑0.4 M͒ at 15°C for immersion timings of up to 3 h. 17 Next, the PANI covered samples were thoroughly washed with Milli-Q water and then undoped with a 1 M NH 4 OH solution for 30 min. A final look of the NW based structure ͑after the AAO membrane removal͒ can be seen in the scanning electron microscopy ͑SEM͒ images shown in Fig.…”