Abstract:
: Lignin isolated from agricultural residues is a promising alternative for petroleum-based
polymers as feedstocks in development of antimicrobial materials. A polymer blend based on silver
nanoparticles and lignin–toluene diisocyanate film (AgNPs–Lg–TDIs) was generated from organosolv
lignin and silver nanoparticles (AgNPs). Lignin was isolated from Parthenium hysterophorus using
acidified methanol and used to synthesize lignin capped silver nanoparticles. Lignin–toluene diisocyanate film (Lg–TDI) was prepared by treating lignin (Lg) with toluene diisocyanate (TDI) followed
by solvent casting to form films. Functional groups present and thermal properties of the films
were evaluated using Fourier-transform infrared spectrophotometry (FT–IR), thermal gravimetry
(TGA), and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM), UV–visible
spectrophotometry (UV–Vis), and Powder X-ray diffractometry (XRD) were used to assess the morphology, optical properties, and crystallinity of the films. Embedding AgNPs in the Lg–TDI films
increased the thermal stability and the residual ash during thermal analysis, and the presence of
powder diffraction peaks at 2θ = 20, 38, 44, 55, and 580
in the films correspond to lignin and silver
crystal planes (111). SEM micrographs of the films revealed the presence of AgNPs in the TDI matrix
with variable sizes of between 50 to 250 nm. The doped films had a UV radiation cut-off at 400 nm as
compared to that of undoped films, but they did not exhibit significant antimicrobial activity against
selected microorganisms.
