Synthesis and properties of polyimide/silver nanocomposite containing dibenzalacetone moiety in the main chain

Trithiocarbonate-Functionalized PNiPAAm-Based Nanocomposites for Antimicrobial Properties

In this study, four trithiocarbonate-functionalized PNiPAAms with different molecular weights were synthesized and used as a matrix to form composites with silver nanoparticles. Nanocomposites with several polymer-to-silver ratios P:Ag⁺ were prepared in order to evaluate the influence of silver loading. UV studies showed a thermoresponsive behavior of the nanocomposites with a thermo-reversibility according to cooling-heating cycles. Release kinetics demonstrated that the release of silver ions is mainly influenced by the size of the silver nanoparticles (AgNPs), which themselves depend on the polymer length. Antimicrobial tests against E. coli and S. aureus showed that some of the nanocomposites are antimicrobial and even full killing could be induced.

Characterization and Antibiofouling Performance Investigation of Hydrophobic Silver Nanocomposite Membranes: A Comparative Study

Biofouling is one of the drawbacks restricting the industrial applications of membranes. In this study, different thicknesses of silver nanoparticles with proper adhesion were deposited on poly(vinylidenefluoride) (PVDF) and polyethersulfone (PES) surfaces by physical vapor deposition (PVD). The crystalline and structural properties of modified and pure membranes were investigated by carrying out X-ray diffraction (XRD) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Scanning electron microscope (SEM) and atomic force microscopy (AFM) analyses were employed to examine the surface morphology and the bacteria anti-adhesion property of the membranes. The morphology measurements confirmed that even though after silver grafting the surface became more hydrophobic, the homogeneity increased and the flux reduction decreased after coating. Moreover a comparison between PVDF and PES revealed that CFU (colony forming units) reduced 64.5% on PVDF surface and 31.1% on PES surface after modification. In conclusion, PVD improved the performance of the membrane antibiofouling, and it is more promising to be used for PVDF rather than PES.

Spectral anion sensing and γ-radiation induced magnetic modifications of polyphenol generated Ag-nanoparticles

A fast one step bio-synthesis for in situ preparation of silver nanoparticles is proposed. The method involves reduction of AgNO3 with an aqueous extract of peanut skin, which is a good source of polyphenols. The silver nanoparticles thus synthesized were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-Vis absorption spectroscopy, Fourier Transform infrared (FTIR) spectroscopy and magnetic measurements. Effect of low dose γ irradiation during the synthesis was studied and their physico-chemical properties were compared with those produced without irradiation. On the contrary to the diamagnetic behavior of bulk silver, the silver nanoparticles thus prepared show a significant ferromagnetic moment component. Variable time exposure to γ-irradiation results in an exponential decay of ferromagnetic component. A freshly prepared solution of silver nanoparticles shows selective spectral changes towards iodide ions at trace concentration (below 50 μM) among a series of 16 other competing anions. The prepared nanoparticles are therefore suitable for anion sensing application.