Effects of RF plasma modification on the thermal and mechanical properties of electrospun chitosan/poly(vinyl alcohol) nanofiber mats

Abstract

On the design and fabrication of biomedical devices, the mechanical integrity and the thermal stability of the materials used are of paramount consideration. In this study, the effects of 13.56 MHz radio frequency plasma modification using argon (Ar) and oxygen (O2) discharges on the morphology, thermal properties, and tensile properties of the nonwoven electrospun chitosan/poly(vinyl alcohol) nanofiber mats were investigated. The scanning electron microscope images showed a significant change in the morphology of the nanofiber mats due to the Ar and O2 plasma treatment. The thermogravimetric-differential thermogravimetry data revealed two major degradation steps for both the pristine samples and the Ar plasma-treated samples due to the molecular backbone degradation and decomposition of polyene and carbonyl residues. However, a third peak was observed for O2 plasma-treated samples which may be due to the oxygen functionalities imparted by the discharge as seen from the Fourier-transform infrared spectroscopy data. Differential scanning calorimetry (DSC) results have shown the glass transition temperature at 65–68 °C and a melting temperature at around 200–220 °C. Also, a decrease in the crystallinity of the plasma-treated samples were noted from the DSC thermograms. A significant (p < 0.05) decrease in the tensile strength, yield strength, Young's modulus, and elongation at break were noted for the plasma-treated samples due to the etching and ablation effects induced by energetic particle interactions. However, the mechanical properties are still comparable with the tensile properties of human tissues such as the skin. These nonwoven mats with tunable properties have potential use in biomedical engineering, particularly as tissue scaffolds, wound dressings, sutures, and antibacterial gauzes.

Effect of Cold Plasma Treatment on Electrospun Nanofibers Properties: A Review

“…In another study, Latag et al studied the impact of Ar or O 2 cold plasma treatments of CS/PVA nanofibers on their mechanical properties. 171 Results showed that Young's modulus was significantly more influenced by O 2 plasma treatment than by Ar plasma treatment. Indeed, the decrease of Young's Modulus was 2.1-times higher after O 2 plasma treatment compared to Ar one.…”

“…In terms of elongation at break, cold plasma treatment of polymer nanofibers tends to lead to a decrease of this parameter, which means an increase in stiffness, in each case of plasma surface modification such as formation of plasma polymer, 1 1 8 cross-linking, 1 2 4 , 1 4 2 or surface etching. 87,88,99,118,171 For example, as for Young's modulus, the decrease of elongation at break of low-pressure cold plasma treated CS/PVA nanofibers was 1.6-times higher for O 2 plasma treatment compared to Ar one. 171 This was again explained by the increase in friability of the materials.…”

“…87,88,99,118,171 For example, as for Young's modulus, the decrease of elongation at break of low-pressure cold plasma treated CS/PVA nanofibers was 1.6-times higher for O 2 plasma treatment compared to Ar one. 171 This was again explained by the increase in friability of the materials. However, only one study demonstrated a nonsignificant increase of this mechanical parameter for an He atmospheric plasma treatment of PCL nanofibers, in opposition with the literature dealing with other polymers.…”

“…In parallel, the effect of plasma treatment in low-pressure conditions leads to a totally different response on the Young's modulus with also an important effect of the gases used on this parameter. Indeed, cold O 2 -containing gas low- pressure plasma treatment of polymer nanofibers led to a decrease in the Young's modulus, 89,100,118,171 whereas nitrogen-containing gas plasma treatment caused its increase. 87,118 Similar results were observed in the case of plasma polymerization onto nanofibers surface.…”

Current Trends in Biomedical Hydrogels: From Traditional Crosslinking to Plasma-Assisted Synthesis

“…The exposed particles and photons in the polymer surface can be modulated by factors such as the plasma operating parameters, polymer substrate, gas chemistry, and the reactor design [117]. The excited plasma species continuously bombard the polymer surface, resulting to the change in the chemistry and characteristics of the surface structure and/or morphology [118,119]. The plasma and surface interaction may result to different processes such as functionalization, crosslinking, and etching.…”