Enhancement of physico-chemical, optical, dielectric and antimicrobial properties of polyvinyl alcohol/carboxymethyl cellulose blend films by addition of silver doped hydroxyapatite nanoparticles

Abstract

Hydroxyapatite nanoparticles doped with silver AgHA-NPs were synthesized successfully then added with various mass fractions to a mixed solution of polyvinyl alcohol (PVA)/ carboxymethyl cellulose (CMC) using the casting technique. Experimentally, the influence of silver doped hydroxyapatite nanoparticles on the structural, optical, dielectric and antimicrobial properties of nanocomposite films was investigated. X-ray diffraction and Fourier transformation infrared spectroscopy were used to explore the structural features of these films. The XRD analysis revealed the amorphous nature of PVA/CMC blend and the intensity of the characteristic peak of the virgin polymers in the nanocomposite spectrum being much reduced as the doping level was increased. The FT-IR spectra indicated that the blend components were miscible by revealing the functional groups of two polymers that interacted through the formation of a hydrogen bond while, the FT-IR spectra of nanocomposite confirmed the good interaction between the blend chains and AgHA-NPs. The morphological graphs of the prepared blend were formed as hexagonal grains with size distribution around 18.36–24.11 μm. The addition of AgHA-NPs changed the surface morphology of the blend significantly. The optical properties of PVA/ CMC blend and nanocomposites films were measured in the 200–800 nm wavelength range. Optical measurements showed that the optical transmittance for pure blend was nearly 90% while it decreased to 50% with increasing AgHA-NPs contents up to 40 wt.%. The energy gap values calculated by Tauc's model and those determined by ASF model are consistent, where their values reduced by AgHA-NPs incorporation. The dielectric constant of all samples were studied in range of temperatures (303–405 K) and from100 kHz to 1.0 MHz, range of frequencies. The Correlated Barrier Hopping (CBH) is the most appropriate conduction mechanism based on the frequency dependence of the ac conductivity. Silver ion release was examined showed that he film loaded with 10 wt.% AgHA-NPs has a small release of silver ion, while the amount of the Ag+ released from the samples increased slowly with increasing the content of AgHA-NPs. PVA/CMC/AgHA films were tested for antibacterial activity against both (Bacillus subtilis) and (Escherichia coli) as well as the anti-fungal activity against (Candida albicans),their results showing an increase in the activity index as the filling level of AgHA-NPs increases. The study confirmed that doping of AgHA-NPs into PVA/CMC improves both electrical conductivity and antimicrobial efficiency and these nanocomposites might be recommended for further work in biomedical applications such as wound dressing and infection control.