Search

The global spread of COVID-19 as well as the worsening air pollution throughout the world have brought tremendous attention to the development of materials that can efficiently capture particulate matter. We suggest that the high porosity of electrospun filters composed of nanofibers could provide minimal obstruction to air flow, while their high tortuosity and surface area-to-volume ratio present an excellent platform to capture particulates. In this study, the removal of nanoscale particles via in-house fabricated cellulose nanofilters is significantly enhanced by chemically functionalizing the fibers' surface via the deposition of the bioinspired glue polydopamine (PDA) or the polycation poly(diallyldimethylammonium chloride) (PDADMAC). The effects of filter packing density, layering thickness, and chemistry on their performance, i.e., their filtration efficiency, most penetrating particle size (MPPS), particle fractional penetration percent, and performance in a high relative humidity environment, were investigated. When evaluated in an extremely hazardous environment (PM concentration ∼2000 μg m-3), the filtration efficiency, pressure drop, and quality factor for the cellulose nanofilters were measured to be >98.0%

Epoxy-based powder coatings are an attractive alternative to solvent-borne coatings. Here, in-house synthesized low glass transition temperature (Tg) particles containing epoxy resin and polymethyl methacrylate formed coatings at room temperature upon impact with a surface. Suspension polymerization was used to prepare particles as a function of diglycidyl ether of bisphenol A (DGEBA) and methyl methacrylate ratios. Higher incorporation of DGEBA decreased the Tg to below ~20°C and eliminated the need to heat the particles and/or aluminum substrates to form coatings. Using an electrostatic powder coating apparatus, a ~70% particle deposition efficiency was achieved on aluminum substrates heated to 200°C. Whereas, at room temperature, high-speed single particle impact experiments proved that particle bonding occurred at a critical velocity of 438 m/s, comparable to commercial cold spray technologies. The in-house synthesized particles used in this study hold potential in traditional and emerging additive manufacturing applications.

In this study, we have improved membrane performance by enhancing ultrafiltration membranes with electrospun nanofibers. The high-porosity nanofiber layer provides a tailorable platform that does not affect the base membrane structure. To decouple the effects that nanofiber chemistry and morphology have on membrane performance, two polymers commonly used in the membrane industry, cellulose and polysulfone, were electrospun into a layer that was 50 μm thick and consisted of randomly accumulated 1-μm-diameter fibers. Fouling resistance was improved and selectivity was retained by ultrafiltration membranes enhanced with a layer of either cellulose or polysulfone nanofibers. Potentially because of their better mechanical integrity, the polysulfone nanofiber-membranes demonstrated a higher pure-water permeance across a greater range of transmembrane pressures than the cellulose nanofiber-membranes and control membranes. This work demonstrates that nanofiber-enhanced membranes hold potential as versatile materials platforms for improving the performance of ultrafiltration membranes.