The potential of chitosan-polygonum minus leaf mediated silver-nanoparticles composite as green conductive biofilm

Silver-nanoparticles (AgNPs) from leaf extract have gained considerable interest from years ago until recently. However, the potential of green-synthesised AgNPs as a conductive filler in polymer biocomposites has not been widely investigated. Herein, a series of biopolymer-silver nanoparticle films were prepared by dispersing the suspension of Polygonum minus leaf mediated AgNPs into chitosan (CS) matrix via solution casting. In this work, the physicochemical properties of the composite films were evaluated, and structural property was analysed by Fourier transform infrared (FTIR) spectroscopy. The electrical conductivity and surface morphology were investigated by two-point probe and scanning electron microscopy (SEM), respectively. From the evaluation of moisture uptake, solubility and degradation tests, the rate of moisture uptake reduced as AgNPs concentration increased whereas the solubility and degradation rate increased with increasing addition of AgNPs. The FTIR analysis confirmed that there was no new covalent bond formed and suggested that AgNPs interact non-covalently with amine and hydroxyl groups of chitosan matrix. The conductivity of the CS-AgNPs films increased with one-order magnitude from 10-8 to 10-7 S/cm compared to pristine CS film. The percolation threshold was achieved at 20 wt% of AgNPs and the highest conductivity was achieved at 30 wt% AgNPs with the conductivity value of 3.20 x 10-7 S/cm. SEM micrographs revealed that the composite film with 30 wt% AgNPs exhibited smooth and homogeneous surface which agrees well with the conductivity results. This CS-Polygonum minus leaf mediated AgNPs composite film shows potential as an alternative for biodegradable biomedical implants, smart packaging and wearable electronics applications.