1 H NMR Study of the Kinetics of Substituted Aniline Polymerization. II. Copolymerization of 2-Methoxyaniline and 3-Aminobenzenesulfonic Acid IDA MAV, MAJDA Z ˇ IGON National Institute of Chemistry, Laboratory for Polymer Chemistry and Technology, Hajdrihova 19, POB 3430, 1000 Ljubljana, Slovenia Received 2 January 2001; accepted 30 April 2001 Published online 00 Month 2001 ABSTRACT: We investigated the kinetics of the oxidative chemical copolymerization of 2-methoxyaniline (OMA) and 3-aminobenzenesulfonic acid (MA) by monitoring mono- mer depletion with 1 H NMR spectroscopy. We adapted a semiempirical kinetic model, previously used for OMA homopolymerization, for the consumption of both OMA and MA monomers with a large difference in their reactivities. The OMA polymerization rate and end conversion showed a similar dependence on the reaction conditions, as described in the first part of this series, for its homopolymerization. Generally, the MA comonomer had an inhibition effect on the OMA polymerization rate. However, an increase in the initial MA concentration resulted in an increased OMA initiation rate. Because of the higher reactivity of OMA compared with that of MA, the OMA conver- sion began before the MA conversion, and both the initiation and propagation rates were higher than those for MA. The molar ratios of the converted monomers (MA/OMA) were always significantly lower than the corresponding MA/OMA feed fractions. They depended on the reaction conditions used for the copolymerization. In particular, higher oxidant or MA concentrations, higher temperatures, and a 1 M DCl concentration favored MA conversion, that is, its insertion into the copolymer. The MA end conversion was much smaller than that of OMA, only up to 23%; for a low oxidant concentration (oxidant/monomer-deficient molar ratio), it was only 6%. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2482–2493, 2001 Keywords: polyaniline derivatives; 2-methoxyaniline; 3-aminobenzenesulfonic acid; chemical copolymerization; reaction conditions; kinetics; 1 H NMR INTRODUCTION The polymerization mechanisms of aniline (ANI) and its derivatives have been studied by many groups employing various techniques. 1–12 It has been suggested that thermodynamic and kinetic factors might be important for polymerization. 6,7 The thermodynamic factor is associated with the monomer oxidation potential 6,7 and has been re- ported to be lower for ANI derivatives than for ANI itself, despite the inductive effect implied by the pendant group on the ring in the ANI deriv- atives. 13 Thus, the oxidation of ANI derivatives and substituted polymers is easier than the oxi- dation of ANI or the parent polyaniline (PANI). The kinetic factor is related to the polymerization time, which is dependent on the steric and elec- tronic effects of substituents. The steric hin- drance to coupling means that the polymerization time increases with the increasing bulkiness of the substituents. However, the electronic effects of the substituents also play an important role: Correspondence to: I. Mav (E-mail: ida.mav@ki.si) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 39, 2482–2493 (2001) © 2001 John Wiley & Sons, Inc. 2482