Transcript Slajd 1 - Uniwersytet Warszawski

The study of dependence of polymeric film morphology on polymerization conditions
K. Bieńkowski, kierownik pracy dr hab. Marek Szklarczyk
Department of Chemistry, Warsaw University
ul. Pasteura 1, 02-093 Warsaw, Poland
Abstract
Experimental
The influence of the supporting electrolyte on the morphological properties of poly(o- metoxyaniline)
(POMA) thin films has been investigated. The POMA films were synthesized electrochemically on the
polycrystalline platinum disks under cyclic voltammetric conditions in aqueous solutions of HCl, H2SO4 and
HClO4, at room temperature.
These films were characterized by Atomic Force Microscopy in tapping mode (TM-AFM). The film thickness
as been investigated by scratching polymer layer.It was found that polymers’ structures received in HClO4 are the
largest and exhibit regular edges. The structures produced in HCl are smaller, and structures received in H2SO4
are the smallest. Structures obtained in HCl and H2SO4 are sphere-shaped.
The working electrodes were made of a polycrystaline platinum
disk. The surface of the electrode was polished with alumina, down to
0,05m, and then it was cleaned with Milipore-Q water in an
ultrasonic bath (Fig.1.).
A Nanoscope III microscope, Digital Instruments, was used to
monitor the surface of the samples, in the electrochemical
experiments a programmed potentiostat was used (EG&G 263A).
b)
a)
Fig.1 Polished platinum electrode
a)
e)
Fig.2. Polymer film a) before scratching b)after scratching
i)
Polymer depth was measured by scratching. Polymer film
before and after this procedure is show in fig. 2. Scratching
allows defining thickness of polymers (as shown in fig.3.).
Thickness of polymer depending on kind of anion and monomer
contentrations is shown in table.1.
The thickest film was for perchloric acid and the thinest
for sulphuric acid. The thicknes of film was growing with
increasing monomer concetration.
b)
f)
Fig.3. Polymer film Crosssection picture after scratching
j)
Table.1. Film polymer depth meausured with scratching
c)
Monomer
concetration
[mol / dm3]
H2SO4
HCl
HClO4
0,01
islands
islands
10 nm
0,03
110 nm
250 nm
340 nm
0,06
400 nm
850 nm
> 2 m
g)
k)
d)
h)
Typical TM-AFM images of polymeric films are shown in Fig. 4.
In H2SO4 and HCl solutions, at monomer concentration 0,01 mol/dm3 the observed
polymer structure is like islands. The surface of electrode seems to be still visible. The
diameter of structures obtained in H2SO4 solution is larger, but their number is smaller than in
HCl solution (Fig. 4 a ,b). The shape of the POMA deposits obtained in HClO4 solution is the
most regular (Fig. 4 c, d).
For monomer concentration 0,03 mol/dm3 (Fig. 4 e-h) structures obtained in H2SO4
solution are smaller than those obtained in HCl solution, but their height is twice as big. For
polymer film obtained in HClO4 solution the two types of structures can be distinguished:
trapezium like and spherical (like for in HCl and H2SO4 solutions).
For monomer concentration 0,06 mol/dm3 in H2SO4 solution fluffy spherical structure
are observed. The chain like structures are obtained in HCl. These kind of structures had
been observed by us earlier [1]. The crystalline like structures are monitored in HClO4
solution, Fig. 4 i-k.
References:
Fig.3. a) b) c) d) monomer concentration 0,01 [mol/dm3] e) f) g) h) monomer concentration 0,03 [mol/dm3] i) j) k) monomer concentration 0,06 [mol/dm3],
a) e) i) H2SO4 b) f) j) HCl c) d) g) h) k) HClO4 left picture present height, right picture present amplitude.
1. Marek Szklarczyk , Emil Wierzbiński, Krzysztof Bieńkowski, Marcin Strawski
Electrochimica Acta 51 (2005) 1036–1043