Langmuir-Schaefer films of
poly (o-anisidine) conducting polymer
for sensors and displays
This is an abstract
for a poster to be presented at the
Fifth
Foresight Conference on Molecular Nanotechnology.
The full paper is available here.
Ultrathin films of polyanilines play an important role for the
application of this class of polymer in nanotechnology. The
nature of the surface properties is critical for the function of
electronics products which may be determined by the layers of
nanometers thickness of polyanilines. In this regards, the
Langmuir-Blodgett (LB) films of polyanilines have been fabricated
at the molecular level [1]. The deposition of quasi ordered and
ordered LB films of polyaniline were also reported, where
emeraldine base dissolved in N-methyl 2-pyrrolidinone
(NMP)/chloroform (CHCl3) could be used to cast LB films using an
aqueous subphase containing neutral or acidic water [1]. The
deposited LB films of polyaniline is used to give rise to an
irregular surface after 10-20 monolayers due to the presence of
NMP. Considering that poly (o-anisidine) (POAS) conducting
polymer is directly soluble in CHCl3, the horizontal lifting
technique [Langmuir-Schaefer (LS)] was employed for the
manufacture of ultra-thin films of the substituted polyanilines,
where each successive deposited monolayer was dried by blowing
nitrogen flux [2,3]. The Langmuir-Schaefer (LS) films of POAS
conducting polymer were then investigated by using UV-visible
absorption, Brewster microscopy, X-ray low angle scattering
ellipsometric, electrochemical and nanogravimetric techniques.
The obtained results revealed a regular deposition during at
least 40 monolayers of POAS LS films. The development of surface
irregularities beyond 40 monolayers of LS films resulted in an
electrochemical kinetics similar to the electrodeposited films.
The electrochemical kinetics in fewer number of monolayers was
shown to be the first electron transfer process. The influence of
the doping anion concentration on the redox properties of POAS LS
films were determined by cyclic voltammetry. The nature of anions
caused significant changes in the redox properties of POAS LS
films. An exploitation of POAS ultra-thin films as sensing
elements in a sensor system or as active layer in an
electrochromic display is in progress in our laboratories.
Namely, the POAS films used for the detection of HCl in water by
conductimmetric measurements revealed a detection limit better
than 0.1 ppm of HCl.
References
[1] M.K.Ram, N.S. Sundaresan, and B.D. Malhotra. J. Phys. Chem.
97, 11580 (1993)
[2] M.K.Ram, S. Carrara, S. Paddeu, E. Maccioni, and C. Nicolini.
Langmuir. 13, 2760 (1997).
[3] S. Paddeu, M.K. Ram, and C. Nicolini. J. Phys. Chem., in
press (1997)
*Corresponding Address:
Claudio Nicolini, Fondazione EL.B.A., Via Medaglie d'Oro 305 -
00136 Rome, Italy, ph: +39 6 35410728, fax: +39 6 35451637,
email: [email protected]
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