Preparation of Surface Adsorbed and Impregnated Multi-walled Carbon Nanotube/Nylon-6 Nanofiber Composites and Investigation of their Gas Sensing Ability.

We have prepared electrospun Nylon-6 nanofibers via electrospinning, and adsorbed multi-walled carbon nanotubes (MWCNTs) onto the surface of Nylon-6 fibers using Triton(®) X-100 to form a MWCNTs/Nylon-6 nanofiber composite. The dispersed MWCNTs have been found to be stable in hexafluoroisopropanol for several months without precipitation. A MWCNTs/Nylon-6 nanofiber composite based chemical sensor has demonstrated its responsiveness towards a wide range of solvent vapours at room temperature and only mg quantities of MWCNTs were expended. The large surface area and porous nature of the electrospun Nylon-6/MWCNT nanofibers facilitates greater analyte permeability. The experimental analysis has indicated that the dipole moment, functional group and vapour pressure of the analytes determine the magnitude of the responsiveness.

Fabrication of nanofibers with antimicrobial functionality used as filters: protection against bacterial contaminants.

A comparative study of antimicrobial activity is done using three different electrospun nanofibers namely-CA, PAN, and PVC used as control and with various amounts of AgNO(3) being treated with UV-irradiation leading to the enhancement of silver nanoparticles. DMF is used as the common solvent which helps to undergo spontaneous slow reduction at room temperature to form silver nanoparticles followed by UV-irradiation using a 400 W source. The time required for the formation of silver nanoparticles is short and they are more or less well dispersed with few such aggregates. The presence of silver nanoparticles is confirmed using various characterization techniques. The antimicrobial activity is studied using nanofibers with fabricated functionality.

Solvent-induced shape evolution of PVP protected spherical silver nanoparticles into triangular nanoplates and nanorods.

The reaction between silver nitrate and poly(N-vinyl-2-pyrrolidone) (PVP) in pyridine at ambient conditions could lead to the formation of spherical nanoparticles or quadrilateral and triangular silver nanoplates, depending on the silver-to-PVP ratio used. It is proposed that the spherical Ag nanoparticles, which were formed early in the reaction, were transformed into nanoplates through an Ostwald ripening process driven by the bridging flocculation of small spherical Ag nanoparticles. This unique and hitherto unreported shape evolution process was carefully followed by a combination of techniques, viz., UV-visible spectroscopy, TEM, and powder X-ray diffraction.