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Chemistry International
Vol. 24, No. 5
September 2002

 

IUPAC Projects


Conducting Polymer Colloids and Nanofilms

Conducting polymers, polyaniline being a typical example, are the object of numerous studies because of their scientific challenge and potential applications. These proposed uses range from micro-electronics, sensors, electronic noses, electromagnetic shielding, and military camouflage, to intelligent materials and anti-corrosion protection. The results of an IUPAC project on the preparation of polyaniline have been recently reported in Pure and Applied Chemistry 74, 857-867 (2002); see highlights in this CI issue.

Polyaniline (PANI) exists in a variety of forms that differ in chemical and physical properties; the most common green protonated emeraldine has conductivity on a semiconductor level of the order of 1-10 S cm-1, many orders of magnitude higher than that of common polymers (<10-9 S cm-1) but lower than that of typical metals (>104 S cm-1).

While the synthesis of many conducting polymers is easy, their poor processibility presents a serious obstacle to application. A new IUPAC project (#2002-019-1-400) addresses this problem by studying two types of processible forms, polyaniline colloids and in-situ-polymerized polyaniline nanofilms. The colloids are produced during the oxidation of aniline with ammonium peroxydisulfate in acidic aqueous medium in the presence of a suitable polymeric stabilizer; polyaniline films grow under reaction conditions of this kind on virtually any surface or interface. The nanofilms are of particular interest because of the brush-like ordering of polymer chains in them.

Members of the task-group from six countries will follow the same preparative protocol in various laboratories, and the properties of the resulting materials will be compared at the international level. For the colloidal forms, the particle size and polydispersity determined by dynamic light scattering will be the main criterion. The films will be characterized with respect to their thickness, assessed by optical absorption measurements after calibration. The results of the project will contribute to the development of reproducible procedures for forming conducting polymers. Various macroscopic and microscopic substrates coated with conducting polymer overlayer can find uses in analytical chemistry, separation science, the catalysis of organic reactions, conducting composite materials and in the development of micro-electronics.

Jaroslav Stejskal <stejskal@imc.cas.cz>

www.iupac.org/projects/2002/2002-019-1-400.html

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