Vol. 24, No. 5
Polymer Colloids and Nanofilms
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
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.
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.