INVESTIGADORES
SANCHEZ Rodolfo Daniel
artículos
Título:
Preparation and characterization of polyaniline-containing Na-AlMCM-41 as composite material with semiconductor behavior
Autor/es:
OSCAR A. ANUNZIATA; MARCOS B. GÓMEZ COSTA; RODOLFO D. SÁNCHEZ
Revista:
JOURNAL OF COLLOID AND INTERFACE SCIENCE
Editorial:
Elsevier
Referencias:
Lugar: Amsterdam; Año: 2005 vol. 292 p. 506 - 519
ISSN:
0021-9797
Resumen:
Composite material formed from a mesoporous aluminosilicate,
Na-AlMCM-41, with conducting polyaniline (PANI) has been synthesized by
an in situ polymerization technique. Studies of aniline adsorption over
mesoporous Na-AlMCM-41 synthesized in our laboratory allowed us to find
the modes in which aniline interacts with the active sites of
Na-AlMCM-41. In order to obtain the best reaction conditions to
polymerize aniline onto Na-AlMCM-41, aniline was first polymerized to
produce pure PANI. Hence, the oxidative in situ polymerization was
carried out by two procedures, differing in the polymerization time and
in static or stirring conditions. Studies of infrared spectroscopy and
UV?vis spectroscopy indicated that higher polymerization time and
static conditions allowed us to obtain mainly polyaniline in emeraldine
form on the host. The N2 isotherm of the
polyaniline/Na-AlMCM-41 composite (PANI/MCM) indicated that the shape
was similar to that of MCM, but the shift to saturation transition to
lower partial pressure shows that the channels are occupied by PANI and
they are now narrowed. The thermal properties of PANI, Na-AlMCM-41, and
composite were investigated by TGA analyses and we found that the
polymer shows higher thermal stability when it is forming the
composite. Scanning electron microscopy indicated that PANI is not on
the outer surface of the host. Conductivity studies show that
PANI/Na-AlMCM-41 exhibits semiconductor behavior at room temperature
and its conductivity was 7.0×10−5 S/cm,
smaller than that of pure polyaniline. PANI/Na-AlMCM-41 conductivity
shows an increase as temperature increases. Magnetic measurements at
room temperature confirmed that the composite has paramagnetic
behavior; at lower temperatures the composite became diamagnetic.