Green Electrospinning and Crosslinking of Polyvinyl Alcohol/Citric Acid

Abstract

The present study reports green electrospinning of polyvinyl alcohol (PVA) / citric acid nanofiber membranes, and the membranes were then crosslinked by heat treatment. The electric conductivity of the PVA aqueous solution increases rapidly and the growth slows down along with the increase of citric acid content. The viscosity of 13 wt% PVA aqueous solutions with citric acid had a small increase and remained stable in one week, which was suitable for electrospinning fibers. Porous, interconnected nonwoven nanofiber membranes were electrospun from a thoroughly mixing of PVA/ citric acid aqueous solution. The membranes were then heat treated at 140 °C for 2 h. The postelectrospinning crosslinked nanofiber membranes were insoluble in water, while the non-crosslinked electrospun nanofiber membranes dissolved instantaneously. FT-IR spectrum, X-ray diffraction, and DSC thermograms reveal that crosslinking of PVA nanofiber membranes occurred through esterfication reaction during heat treatment.

An electrospun citric acid modified polyvinyl alcohol scaffold for vascular tissue engineering

“…Citric acid modification of PVA provided polyesters with good biocompatibility and anticoagulant properties. Jingjing Shi and Yang 28 report the electrospinning of PVA/citric acid and the crosslinking of the same using heat treatment. Similarly, the approach of citric acid crosslinking has been studied by Stone et al, 29 where a blend of alginate/PVA/citric acid was electrospun and then crosslinked at 140°C for 2 h. To avoid the heating process after the spinning is complete which may alter the fibre structural properties, we have used the prepolymer solution for the preparation of the spun membranes.…”

Applying different techniques for evaluating the resistance to moisture of electrospun PVA nanofibers

“…The mixture was agitated for 1 h, under stirring at 1150 rpm and 80ºC. Crosslinking agent citric acid (5.0 wt.% based on the PVA mass, according to Esparza et al, 2017;López-Córdoba et al, 2016;Lv et al, 2019;Yang, 2015;Stone et al, 2013) was then added for further stirring (30 min). The solutions were then left to degas overnight.…”

“…The humidity and temperature of the room were maintained respectively in 48% R.H. and 25ºC in average. The spun fibers were maintained in a vacuum oven at 140ºC for 2 h, following previous researches that crosslinked PVA fibers with citric acid (Esparza et al, 2017;Lv et al, 2019;Yang, 2015;Stone et al, 2013). Fourier Transform Infrared spectroscopy (ATR-FTIR, Model Tensor 27, Bruker) was used to confirm the occurrence of crosslinking between PVA and citric acid.…”

“…However, the presence of the surfactant also could lead to decreasing resistance of the nanofibers in relation to humidity. Although the mass loss after immersion in water (Esparza et al, 2017;López-Córdoba et al, 2016;Lv et al, 2019;Miraftab et al, 2015;Yang, 2015;Stone et al, 2013) and water contact angle measurements (Fang et al, 2018;Lee et al, 2016) are traditionally used to evaluate the resistance to water, these methodologies seem not attesting the usefulness of the PVA filter media in air filtration, a process in which water could be present as moisture in the air stream, but there is no severe condition like immersion in pure water.…”

Use of Ultrasound to Prepare Permeable Crosslinked PVA Membranes

“…However, crosslinking process reduces the hydrophilicity of PVA membranes as well as their permeability. Although several alternative modifications have been used to address the reduced hydrophilicity and permeability of c-PVA membranes, e.g., grafting [2,5,13,14], blending [5,8,14] and filling with fine inorganic particles [1,[15][16][17][18][19][20][21], the use of efficient, eco-friendly green methods for the preparation of c-PVA membranes to minimize or eliminate undesired chemicals [22][23][24][25][26][27] is important, since in the last decade, increasing environmental awaerness needs to use eco-friendly methods.…”