Enhanced Microwave Synthesis: Fine-Tuning of Polyaniline Polymerization

A series of energy- and time-efficient enhanced microwave syntheses (EMS) of polyaniline (PANI) have been performed and are discussed herein. The syntheses were performed at different microwave power levels while keeping the reaction system at a constant temperature of 24 ± 1 °C, with the samples extracted after 10 min of reaction. Molecular weights were determined with GPC (gel permeation chromatography) and showed that the molecular weight of the microwave-generated materials depends on applied power: the higher the power level, the greater the molecular weight. The chemical structure was investigated by FTIR and UV–vis spectroscopy, while the morphology was imaged using scanning electron microscopy (SEM). FTIR and UV–vis spectroscopy confirmed the formation of PANI, and SEM indicated the presence of a mixed morphology, with a prevalence of nanofibers with different aspect ratios. The conductivity of the samples (ca. 3–3.5 S cm^–1) was found to be relatively independent of microwave power levels. Surface area measurements were carried out using Brunauer–Emmett–Teller (BET) method, with samples synthesized using EMS showing higher surface areas when compared with conventionally synthesized PANI. The fact that molecular weight depends on applied power implies that microwave-enhanced synthesis can be used to fine-tune PANI reaction conditions, directing it toward specific properties