Separation and spectroscopic/molecular weight analysis of crude and purified polyaniline(s)

Inherently conducting polymers have gained increased attention due to the many unique optoelectronic properties they exhibit. The properties of polymers vary depending on the purity, molecular weight distribution, and synthetic conditions; all of these are important for widespread use in many touted applications. These studies have been undertaken in order to separate the low molecular weight and high molecular weight fractions from the crude product. The results demonstrate an efficient separation of different molecular weights of polyaniline (PANI) by the soxhlet extraction procedure with a series of solvents (methanol, chloroform, tetrahydrofuran and benzyl alcohol). The purified products and extracts were characterized by gel permeation chromatography (GPC) to determine their molecular weight distributions. UV-visible, infrared, and nuclear magnetic resonance (NMR) spectroscopy were performed for structural analysis of the polyanilines. Low molecular weight polyanilines can promote the aggregation in polyaniline chains and increase the solubility of polyanilines.