Composition tuning of scalable antibacterial polyaniline/chitosan composites through rapid enhanced microwave synthesis

Abstract

Biopolymers such as chitosan (Ch) can be included with the conducting polymer polyaniline (PANI) to improve mechanical properties and processability to allow the benefits of this multifunctional material to be realised. However, scalable processes for fabrication of these materials are lacking. We present a facile and rapid method based on enhanced microwave synthesis of PANI and PANI/Ch composites using 1.25 M aqueous hydrochloric acid (HCl) media at 93 W applied microwave power for the duration of 10 min at room temperature. Potassium iodate (KIO3) was chosen for aniline (An) polymerisation as a well-suited oxidising agent for scalable production of high quality PANI over a broad range of synthesis conditions. FTIR spectra of PANI/Ch samples confirm integration of PANI in the composite structure with the presence of all characteristic PANI bands. SEM analysis of PANI/Ch composites exhibited different morphologies from pure PANI fiber-like nanoporous morphology and these differences are more pronounced with the increase of molecular weight of Ch in the PANI/Ch composites. A comparative study of PANI/Ch composites prepared by chemical and enhanced microwave approaches with different Ch molecular weights and a mole ratio of An:Ch 1:1 demonstrated differences in morphology based on the method of synthesis for the same molecular weight of Ch, although control PANI sample has similar nanoporous morphology for both methods of preparation. Antibacterial evaluation results of all PANI/Ch composite samples against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria showed greater bactericidal efficacy against both type of bacteria than pure Chs and PANI samples. Our comprehensive study suggests that the eco-friendly enhanced microwave method can be used to fine-tune the morphology and structure of the antibacterial PANI/Ch composites toward specific applications and as a favourable alternative method for large-scale industrial production of these polymer composites.