Olcay Eren

Synergistic effect of polyaniline, nanosilver, and carbon nanotube mixtures on the structure and properties of polyacrylonitrile composite nanofiber

In this study, various amounts of carbon nanotubes (CNTs), nanosilver (AgNPs), and polyaniline (PANI) were incorporated at the same pot into the structure of composite polyacrylonitrile (PAN) nanofibers, which were produced by electrospinning process in order to see synergistic effect of the additives on the final properties of the composite materials. Performance and characteristic properties of composite nanofibers were analyzed by tensile tester, electrical conductivity meter, Fourier Transform Infrared Spectroscopy, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and antimicrobial activity test. Statistical analysis (analysis of variance) was performed to see whether the differences were statistically significant or not. It was seen that samples with AgNPs had higher breaking strength and electrical conductivity than the samples with CNTs. Generally, PANI improved the crystallinity of the composite material more than the nanoparticles (CNTs and AgNPs). Even though each of the nanoparticles was used in low concentrations, the composite materials (PAN–1CNT–1AgNO3–R and PAN–PANI–1AgNO3–R) gained antimicrobial properties due to the synergistic effect of additives. The results suggested that PAN composite nanofibers with 3 wt% PANI and 1 wt% AgNO3 generally presented better performance than the other samples in terms of electrical conductivity, antimicrobial activity, mechanical strength, crystallization, and thermal stability.

Polyacrylonitrile-polyaniline composite nanofiber webs: Effects of solvents, redoping process and dispersion technique

This study was carried out to examine the effect of different solvents (DMSO, NMP, DMF) and solvent mixtures, application of dispersion and mixing techniques during solution preparation and redoping process on polyacrylonitrile (PAN) and camphorsulfonic acid (CSA) doped polyaniline (PANI) composite nanofibers. It was observed that nanofibers produced from DMSO and NMP solvents had larger fiber diameters than nanofibers produced from DMF. When the crystallinity of the 100 % PAN nanofibers were compared, the nanofibers electrospun from DMSO had the lowest crystallinity values. The tensile breaking stress values of the nanowebs produced from DMSO and NMP were higher than nanowebs produced from DMF while the breaking elongation values of the nanowebs produced from DMF was higher. Mechanical dispersion technique resulted in higher tensile breaking stress values than corresponding magnetic stirring. The redoping process also affected the tensile properties of the nanowebs by increasing the breaking stress values and decreasing the breaking elongation values. When DMSO was used as a solvent for the production of composite nanofibers, the electrical conductivity values at around 10−6 S/cm were obtained corresponding to the semiconductive material range. The use of solvent mixtures resulted in better conductivity values than their counterparts. When CSA-NMP and CSA-NMP/DMF were compared, the nanofibers produced from the solvent mixture had higher conductivity values. On redoping, the conductivity increased 10 times and reached 1.2×10−5 S/cm. The reference samples with DMSO had the lowest cyclization temperature and enthalpy. Addition of PANI increased the thermal stability of the composite nanofibers in comparison with pure PAN.

The effect of dispersion technique, silver particle loading, and reduction method on the properties of polyacrylonitrile–silver composite nanofiber

The effect of dispersion technique, reduction method, and the amount of silver nanoparticles on the properties of composite polyacrylonitrile nanofiber containing silver nanoparticles is analyzed using differential scanning calorimetry, scanning electron microscopy, electrical conductivity, tensile testing, X-ray diffraction, and antimicrobial efficiency measurements. Composite nanofibers reduced by hydrazine hydroxide result in smaller diameter, higher electrical conductivity, higher breaking strength, higher cyclization enthalpy than the samples reduced by xenon arc method. Reduction process results in smaller diameter and higher breaking strength than those of non-reduced nanofiber web containing AgNO3 nanoparticles. Dispersion by ultrasonic homogenizer/bath provides higher breaking strength, electrical conductivity than the samples dispersed by only magnetic stirrer. An increase of silver nanoparticle generally results in an increase of enthalpy, a decrease of both cyclization temperatures and crystallinity. While 1 wt% AgNO3 loading is suitable for high breaking strength, 3 wt% AgNO3 loading is suitable for both high electrical conductivity and antimicrobial properties. Insulator polyacrylonitrile polymer becomes a semiconducting material.