Reversible swelling as a strategy in the development of smart membranes from electrospun polyvinyl alcohol nanofiber mats

Abstract

This work presents an electrospun nanofibrous membrane for water treatment, designed to reduce its pores through polymer swelling to retain contaminants, and after that, reopening them for easy cleaning. It consists of a polyvinyl alcohol (PVA) mat crosslinked with a natural agent to avoid water solubility but allow a high swelling of its nanofibers. Then, when the membrane is brought into contact with water, a transitory state occurs during which nanofibers increase their diameter 68%, closing the pores between them. For studying the swelling reversal effect, distilled water filtering was used observing a decrease in the permeate flow over time until a steady state is reached. This phenomenon is explained by the closure of pores, and it is described with a fouling model widely used in the literature. Thanks to this decrease in the pore size, the membrane achieves a rejection rate much higher than conventional PVA electrospun membranes, being capable to retain 20 nm nanoparticles with a rejection rate up to 99%. Swelling is reversible through a simple drying process, which allows reopening the pores and cleaning the fouling easily. Both the membrane and its use strategy extend the capacity of electrospun mats in a sustainable way.

Preliminary Evaluation of 3D Printed Chitosan/Pectin Constructs for Biomedical Applications

“…An important characteristic of polymeric scaffolds for skin regeneration applications is their dehydration ability which is also referred as swelling reversibility. Swelling reversibility is interlaced to the reusability of the scaffolds [ 66 ]. Figure 8 c shows the relative water content of the samples and their behavior through the dehydration process.…”

A Highly Efficient Nanostructured Sorbent of Sulfuric Acid from Ecofriendly Electrospun Poly(vinyl alcohol) Mats

“…The possibility of reuse was confirmed for at least five cycles, and although the efficiency in the acid uptake decreased over the cycles, the lower achieved value is comparable to the one of commercial acid absorbent pads of sole use. 30 This decrease in the acid uptake efficiency over time until a steady state is reached (Figure 10), is the result of swelling reversal of a material's fibers as stated by Cimadoro et al 31 They found that a PVA membrane reversed its swelling 72% after the first cycle. 31 The possibility to completely regenerate the material through a desulfonation procedure was also explored.…”

“…30 This decrease in the acid uptake efficiency over time until a steady state is reached (Figure 10), is the result of swelling reversal of a material's fibers as stated by Cimadoro et al 31 They found that a PVA membrane reversed its swelling 72% after the first cycle. 31 The possibility to completely regenerate the material through a desulfonation procedure was also explored. The sulfonic acid group (−SO 3 H) can be removed from a cyclic substrate by heating the sulfonated product in the presence of diluted aqueous sulfuric acid.…”

“…The as-spun PVA mat (material A) was exposed to three different heat treatments (HTs) as shown in Figure . In all cases, mats were exposed for at least 5 min at 195 °C to ensure water stability …”

“…In all cases, mats were exposed for at least 5 min at 195 °C to ensure water stability. 18 The morphology of developed materials was observed by SEM using a field emission gun (Zeiss DSM982 Gemini, Germany). The ATR-FTIR (model 4100, Jasco, Japan) spectra were recorded in a range from 4000 to 600 cm −1 with a resolution of 4 cm −1 .…”