Abstract:
Plasma polymerized o-methoxyaniline (PPOMA) thin lms of di erent thicknesses
were synthesized at room temperature on to glass substrates using a capacitively
coupled plasma polymerization reactor. The thicknesses of the PPOMA lms were
measured by multiple-beam interferometric method. A smooth and
awless surface
of PPOMA thin lms was observed from the surface morphology observation
through the Field Emission Scanning Electron Microscopy. The topological information
through the Atomic Force Microscopy analyses revealed that the surface roughnesses
of PPOMA thin lms were reasonably low ( 1 nm). The chemical analyses
through the Energy dispersive X-ray Spectroscopy report con rmed that the PPOMA
thin lms consisted of a dominant proportion of carbon along with a small portion of
oxygen and nitrogen. The structural analyses through the Attenuated Total Re
ectance
Fourier Transform Infrared analyses showed changes in the chemical structure
(bonds) of PPOMA thin lms compared to those in o-methoxyaniline. Di erential
Thermal Analyzer (DTA) and Thermogravimetric Analyzer (TGA) were used for the
thermal analyses of the PPOMA thin lms in oxygen and nitrogen environments. The
DTA curve showed the two-stage degradation reaction in oxygen environment indicating
the maximum weight loss at the temperature of 790 K, whereas a single-step
reaction in nitrogen environment showed the maximum weight loss at the temperature
of 683 K. The TGA curves showed that the PPOMA was thermally stabler up to
the temperature of around 507 K in both the environments. It also revealed that the
weight loss (around 70%) of PPOMA is signi cantly larger in oxygen environment
compared to that (around 27%) in nitrogen environment, up to the temperature of
823 K. The optical analyses were carried out through the Ultraviolet-visible spectroscopic
analyses. The average values of direct and indirect transition energies were
obtained as 3.25 ( 0:10) eV and 1.70 ( 0:20) eV respectively. The direct current
electrical measurements of PPOMA thin lms indicated that the conduction current
obeys Ohm's law in the low voltage region (< 10 V) while it shows non-ohmic nature
at the high voltage region (> 10 V). The dominant type of conduction mechanism
was found as the space charge limited conduction type through the analysis of the
dependence of current densities on thicknesses of the PPOMA thin lms. The activation
energies were calculated for low and high applied voltages, at low and high
temperatures in both cases. Finally, the possible applications of the PPOMA thin
lms are brie
y suggested.
