SYNTHESIS OF HIGH-MOLECULAR-WEIGHT POLYANILINE AT LOW-TEMPERATURES

The oxidative chemical polymerization of aniline in hydrochloric acid solution has been extensively studied at low temperatures. The resulti ng polyaniline has a molecular weight up to ten times higher than that prepared at room temperature. Polyaniline of high molecular weight ma y be obtained by carrying out the polymerization at low temperatures, typically between -25 and -30 degrees C. This requires the use of an i nert solute (lithium chloride is the preferred choice) to keep the aqu eous reaction medium mobile. Among the reaction parameters studied whi ch affected the molecular weight of the polymer were: (a) reaction tem perature; (b) solution pH at the start of the reaction; (c) molar rati o of oxidant:aniline; (d) oxidant addition time; (e) total reaction ti me.