Microgravimetric study of electrochemically controlled nucleophilic addition of sulfite to polyaniline.
The sulfonation of polyaniline (PANI) films by nucleophilic addition of sulfite ion has been controlled through the polymer oxidation state under electrochemical control. The process was monitored by in situ electrochemical quartz crystal microbalance (EQCM), and the polymer oxidation was accomplished by electrode potential steps in sulfite aqueous solutions. The nucleophilic addition of sulfite to PANI only takes place on the oxidized polymer. From the ratio of added mass to the injected charge, the degree of sulfonation has been obtained with a yield as high as 50%. It has been observed that the ion-exchange mechanism during the oxidation-reduction process in the resulting sulfonated polymer is analogous to the polymer produced by electrophilic sulfonation of polyaniline or by copolymerization of aniline with aminosulfonic acids, unlike the ionic exchange observed for unmodified PANI.
Grumelli
Doris E
DE
INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, AR-1428 Buenos Aires, Argentina.
Forzani
Erica S
ES
Morales
Gustavo M
GM
Miras
Maria C
MC
Barbero
Cesar A
CA
Calvo
Ernesto J
EJ