Microwave-assisted simultaneous synthesis of conducting, non-conducting and cross-linked polymers from sodium 2,4,6-tribromophenolate and LiOH

Abstract

Poly(dibromophenylene oxide) (P) and conducting polymer (CP) and/or cross-linked polymer (CLP) were synthesized simultaneously from sodium 2,4,6-tribromophenolate and LiOH by microwave energy in a very short time interval. Polymerizations were carried out (i) under constant microwave energy and constant amount of water with different time intervals ranging from 1 to 20 min, or (ii) at constant time intervals and constant amount of water with variation of microwave energy ranging from 90 to 900 W, or (iii) at constant time intervals and constant microwave energy with changing amount of water ranging from 1 to 5 ml. Polymers P and CLP were synthesized in 1 ml water. As the amount of water was increased to 3 ml and 5 ml, only the synthesis of CP and CLP were achieved respectively. The synthesized polymers were characterized by elemental analysis, FT-IR, 1H- and 13C-NMR, X-ray diffraction spectroscopy, SEM, DSC, TGA, ESR, light scattering and conductivity measurement. The direct synthesis of highly conducting polymer, with a conductivity of 4 × 10−2 S/cm2 was achieved in the absence of an applied doping process in a very short time sequence. The optimum conditions for synthesis of P, CP and CLP were for (i) 180 W for 2 min in 1 ml water, for (ii) 900 W for 5 min in 3 ml water and for (iii) 900 W for 10 min in 5 ml water, with maximum values of 24.5, 53.1 and 80.8%, respectively.