Multi-layered micro/nanofibrous nonwovens for functional face mask filter

Abstract

The worldwide COVID-19 pandemic has led to an attention on the usage of personal protective face masks. However, the longevity and safety of the commercial face masks are limited due to the charge dissipation of the electret meltblown nonwovens, which are dominate in the face mask filters. Herein, we design a type of multi-layer structured nonwovens using meltblowing and electrospinning technologies. The complex nonwovens involving meltblown and electrospun fibers are designed to possess multilevel fiber diameters and pore sizes. The micro/nanofibers with porous and wrinkled surface morphologies can well capture particulate matters (PMs), and the multilevel pore sizes contribute to low air resistance under high filtration efficiency. Airflow field simulation was carried out to understand the pressure distribution within the nonwovens in the filtration process. Meanwhile, by adding Ag nanoparticles (AgNPs) as additives, the nonwovens exhibit excellent antibacterial performance. The resultant nonwovens exhibit filtration efficiency of 99.1% for PM 0.3 and low pressure drop of 105 Pa under the 10.67 cm/s inlet air velocity, and antibacterial rate of > 99.99% for Escherichia coli . These performances and functions make the designed complex nonwovens a promising filter core for face masks. Electronic Supplementary Material Supplementary material (Fig. S1. The filtration efficiencies of a brand of surgical mask changes with the storage time under the condition of 100% humidity. Fig. S2. The FE-SEM images of the fibers after blocking PMs. Fig. S3. Illustration of 3D structure models of the nonwovens. Fig. S4. Diameter distribution of AgNPs. Table S1. The structure parameters and filtration performances of the PP-M fibers with and without pores and wrinkles. Table S2. Filtration performance of PP-M/PLA-M/PLA-N nonwovens and commercial face masks. Table S3. The structural parameters for the nonwovens. Table S4. The filtration efficiencies and pressure drops of the PP, PE spunbonded nonwovens, and PP-M/PLA-M/PLA-N@AgNPs nonwovens) is available in the online version of this article at 10.1007/s12274-022-4350-2.

Recent advances and future perspectives in engineering biodegradable face masks

“…Silver nanoparticles incorporated in PLA nonwoven face mask filters exhibited antibacterial activity up to 99.99% against E. coli while maintaining the pressure drop at 105 Pa and high filtration efficiency (99.1% for PM 0.3 ). 122 NanoLayr Ltd, a filter manufacturer in New Zealand has fabricated a three-layered face mask for which the middle layer is composed of electrospun PLA nanofibers and manuka triketone as the antimicrobial agent source, sandwiched between two outer layers of PLA spun-bonded non-woven fabric counterparts. 123 The PLA/manuka triketone filter media showed a virus reduction of 99%, 99.82% and 99.69% against influenza A, human coronavirus 229E and SARS-CoV-2 respectively after two hours of contact time, ≥98% filtration efficiency and pressure drop of 48–59 Pa (air velocities = 8 L min −1 ).…”

Electrospun nanofibers for medical face mask with protection capabilities against viruses: State of the art and perspective for industrial scale-up

“…where a higher capture of fine particles with size below 0.5 μm was attributed to the addition of electrospun nanofiber with smaller inter-fiber space on MB-based PE membrane, which was made instead of larger pores [ 160 ]. Furthermore, experimental evidence based on water vapor transmission rate (WVT) revealed that multilayer membranes based on electrospun and MB fabric provided higher values of WVT compared to that observed in commercial face masks, thus proving a better passage of moisture air during exhalation, and therefore a less human discomfort in wearing the mask [ 150 , 160 ] ( Fig. 6 k).…”

Fabrication of Laminated Micro/Nano Filter and Its Application for Inhalable PM Removal

“…However, there are still many drawbacks with pure electrospun membrane for air filtration, such as high cost, low dust holding capacity [ 20 , 21 ]. To overcome these drawbacks, a lot of research has been done such as surface structure design [ 22 ], fiber and pore size optimization [ 23 , 24 ] and fiber surface modification [ 25 ]. PVDF (Polyvinylidene fluoride) nano fibers were widely studied for energy harvesters and tactile sensors due to its piezoelectric property [ 26 , 27 , 28 , 29 ].…”