Effect of TiO2 nano‐filler on the electrical conductivity and free volume parameters of PSAN/TiO2 nanocomposites

To explore the effect of filler on the electrical conductivity of polymer nanocomposites, polystyrene co‐acrylonitrile and TiO2 (PSAN/TiO2) nanocomposites of different TiO2 wt% have been prepared. The microstructural characterization has been performed by positron annihilation lifetime spectroscopy (PALS). Positron lifetime parameters viz. o‐Ps lifetime (τ3) and free volume size (Vf) decreases up to 0.6 wt% suggests the filling of the cavities by Ti3+ and O− ions as well as complex formation. The increased free volume size (Vf) after 0.6 wt% of TiO2 was attributed to the o‐Ps annihilation at the interface of PSAN and TiO2 nanoclusters. The variation of electrical conductivity at lower and higher concentration of TiO2 is attributed to the blocking effect and space charge effect, respectively. The electrical conductivity decreases along with the free volume sizes at lower concentration of TiO2 due to the hindrance of the ions mobility. The increased conductivity with the increased free volume sizes indicates the formation of more void space at the interface due to the formation of TiO2 nanoclusters. The surface morphology of the nanocomposites studied by scanning electron microscopy (SEM) shows uniform dispersion at the lower wt% of TiO2 and increased size of nanocluster formation at the higher concentration of TiO2 nanoparticles in PSAN matrix. The crystallinity evaluated by X‐ray diffraction (XRD) results also indicates the formation of TiO2 nanoclusters between 0.6 and 1.0 wt% of TiO2. Fourier transform infrared spectroscopy (FTIR) suggests the improved chemical and physical interaction between the functional groups of TiO2 and polymer side chain. POLYM. COMPOS., 39:1403–1412, 2018. © 2016 Society of Plastics Engineer

Ionic and electronic transport in PSF/NiO and PSF/TiO2 polymer nanocomposites: a positron lifetime study

Polymer nanocomposites of PSF/NiO and PSF/TiO2 with different wt of nanofiller have been prepared and subjected to SEM, FTIR, X-ray diffraction, DSC, PALS and electrical conductivity measurements. The relationship between crystallinity, surface morphology, glass transition temperature, free volume and the electrical conductivity of these polymer nanocomposites was systematically investigated. The increased AC and DC electrical conductivity at the lower concentration of NiO suggests the increased number of mobile ions and electrical charge carriers due to the increased crystallinity of PSF/NiO composites. The decreased conductivity at higher concentration of NiO indicates the reduced conducting pathways for the mobility of ions and the electrical charge carriers due to the decreased crystallinity by the nanoparticles aggregations. The increased AC and DC electrical conductivity with increasing the concentration of TiO2 indicates more and more positive charges in front of the cathode, resulting proper polymer-nanofiller interface due to the conductivity chain formation through the nanoparticles aggregation. The surface morphology of PSF/NiO and PSF/TiO2 nanocomposites show dispersion of nanoparticles over the surface of PSF matrix and the formation of filler aggregates at higher wt of nanofiller incorporation. The increased glass transition temperature (Tg) and decreased o-Ps lifetime (τ3) at the lower concentration of NiO and TiO2 indicates the improved interfacial interaction between the surface of NiO and TiO2 nanoparticles with the side chains of PSF polymer matrix. This is evident from Fourier Transform Infrared Spectroscopy (FTIR) studies. The increased o-Ps lifetime (τ3) at higher concentration of NiO and TiO2 suggests the increased interfacial space for o-Ps to annihilate at the interface of PSF and NiO and TiO2 nanoclusters

Green Synthesis of Gold Nanoparticles from Vitex negundo Leaf Extract to Inhibit Lipopolysaccharide-Induced Inflammation Through In Vitro and In Vivo

Gold nanoparticles (AuNPs) have wide applications in the field of diagnosis and treatment of diseases which are attributed to their compatibility and high efficiency of drug delivery, because of their eco-friendly nature and easy handling. In the current study, we have used an extract of Vitex negundo, a traditional anti-inflammatory folk medicine in India and synthesized gold nanoparticles (VnAuNPs), to know the effects of anti-bacterial, antioxidant, and anti-inflammatory properties both in vivo and in vitro. V. negundo leaf extracts (VnLE) per se yielded high flavonoids, saponins, tannins, alkaloids, glycosides, phenols, terpenoids. The synthesized VnAuNPs in leaf extracts was confirmed by UV-vis spectra at 543 nm and further by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM) and through Dynamic light scattering (DLS). The FTIR showed the peaks at 3345, 1638, 692, 683, 662 cm(-1) which are responsible for the reduction and capping of gold nanoparticles. The size and shape of the AuNPs were determined by SEM. DLS study analysed the particle size distribution of AuNPs. The VnAuNPs showed significant antibacterial activity on both gram positive and negative bacteria. VnAuNPs also showed strong antioxidant (DPPH, H2O2 scavenging, Nitric oxide scavenging power and reducing power) activities when compared to VnLE extract. The VnAuNPs exhibited strong anti-inflammatory activities (COX-2, lipoxygenase and xanthine oxidase inhibitory activity) in in vitro (HeLa cell model) and in vivo study of carrageenan induced paw edema model in Swiss albino mice (paw edema and acetic acid-induced writhing test). Results suggested that the synthesized VnAuNPs are potential candidates for treating inflammatory diseases and may find application in clinical studies