Note: Descriptions are shown in the official language in which they were submitted.
WO 2023/060027
PCT/US2022/077443
ELECTROSPU.N NANOFIBROUS POLYMER MEMBRANE
FOR USE IN AIR FILTRATION .APPLICATIONS
CROSS-RE..FERENCE TO RELATED APPL1C-.ATIONS
1-00-01]
This .application claims, the benefit of U.S. Pro-visional Patent
.AppliCatiOn Serial
No. 631262,246, filed on October 7,2021, .and 63/267,877, filed on February
11, 2022; the
disclosures of ....vhich are hereby incorporated in theirentireties herein by
reference.
-BACKGROUND
-Field. of the Invention
100021
The present disclosure re kites to materials for use in air filtration
applications
Description of the Related Art
10003]
Clean air is .:..!enerally deemed a basic requirement for promoting
human health and
-well-hcing. Air pollution
__________________________________________________________ including
particulate matter (PM) and chemical and biological
-contaminants---Vises a significant threat to health worldwide. The World
Health Organization
-reported that air pollution led to 4..2. million .premature. deaths.
worldwide in 2016..= See World.
Realth Organization, -Ambient (Outdoor) Air Pollution," .2021 (available at:
intos:ilwww.who. int/mine ws-roornitaet-stieetside ta Fa tribient- outdoor)-a
(y-an d-
health). Poor air quality, including hazardous pollutants and pathogens,
increases, the risk, of a
variety of diseases, including respiratory infeetiQr1S.õ cardiovascular
disease, chronic
obstructive pulmonary disease and various., types of cancer id.
100041
The use of air filters to reduce human exposure to hazardous pollutants
and
pathogens is highly desirable. However, currently available commercial air
filters are
frequently = composed of multiple layers of thick .fibrous materials. to
achieve high filtration
efficieriey, which results in significant airflow resistance. See, e.g., Wang
C., ei 'al.. "Silk
Nano-fibers as High Efficient and Lightweight. Aix Filter,"' Nano Rex. 2016,
9, 2590-97: There
has been an interest in the use of nanofibers in air filtration to generate
high efficiency, low
.airflow resistance, lightweight air filters. See,
Wang, C.-g., et al. "Removal of
Nanoparticles from Gas Streams hy Fibrous Filters; A Review." id.. Eng.
0.7ern. Res, 2013,
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52, 5-17; Peng, L., et al. "Air Filtration in the Free Molecular Flow .Regime:
A Review of
High-Efficiency Particulate Air Filters Based on Carbon Nanotubes," Small,
2014, 10, 4543--
61. In addition, due to the large surface area of nanofiber surfaces, ills
possible to modify
nanofiber surfaces to achieve multi-functionality.
100051 Air filtratiOn is an important tool for enhancing indoor
air quality. Thus, air filters
incorporating .nanofibers may be very useful in .HVAC applications.
100061 It is also desirable to remove volatile organic compounds
(VOCs) in air filtration
applications, as various VOCs have a number of well-established detrimental
health effects.
On account of various shortcoming of conventional methods of removing VOCs
from indoor
air, a number of recent efforts have fbcused on the use of photocatalytic
degradation of VOCs.
See. e.g., Singh, P., et al. "A Review on Biodegradation and Photocatalytic
Degradation of
Organic Pollutants: A Bibliometric and Comparative Analysis," J. Clean. Prod.
2018, 196,
1669-80; Malayeri, M., et at "Modeling of Volatile Organic Compounds
Degradation by
Photocatalytic Oxidation Reactor in Indoor Air: A Review," Bitikt Environ.
2019,154, 309-
23.
100071 Photodegradation of VOCs may generate carbon dioxide (COO.
Global climate
change caused by the emission of massive amounts of greenhouse gases,
including carbon
dioxide (CO2), is causing alarming threats to the environment and public
health. Thus, CO2
capture technologies have drawn tremendous attention. See, e.g., Qi, G., et at
'High
Efficiency .Nanocomposite Sorbents for C0.2. Capture Based on Amine-
Funetionalized
Mesoporous Capsules," Energy Environ. Sc!, 2011, 4, 444-52; Zainab, G., et at
"Electrospurt
Carbon Nanofibers with Multi-Aperture/Opening Porous Hierarchical Structure
for Efficient
C.02 Adsorption," .1. Colloid Intel:Mee Sc!. 2020, 561, 659-67; Wang, X., et
al
"Polyetheramine Improves the CO2 Adsorption Behavior of Tetraethylenepentamine-
Functionalized Sorbents," Chem. Eng. J. 2019, 364, 475-84. Coupling
photodegradation
processes with CO2 removal will thus reduce .the impact of phOtocatalytic VOC
removal
processes on global climate change.
100081 In addition, it may be desirable in various applications
to functionally modify air
filters to facilitate pathogen removal. Infectious respiratory pathogens are
typically transmitted
by droplet, aerosol,. or airborne transmission of particles expelled, from the
respiratory tract of
an infected person by coughing or sneezing, or in some cases by simple
exhalation. To prevent
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this fornt of transmission, air filters may be used both to remove pathogens
from ambient air
and to protect individuals from inhaling any pathogens present in ambient air.
[00091
For applications focused on protecting individuals from pathogens
present in.
ambient air, facemasks and respirators have been developed that either
mechanically intercept
the infectious particles or that disarm the infectious particles using a
variety of mechanisms.
Therefore, many research and development etThrts have been made to enhance the
filtering
efficiency of facemasks and respirators.
100101
The COV1D-19 pandemic has highlighted the need for functional
protective textiles
for a variety of applications. Functional protective textiles are particularly
important for use
in protective clothing for medical professionals, field workers, and soldiers.
See, e.g.., au, Q.,
et al. "AQC Functionalized CNes/INA-co-PE Composite Nanofibrous Membrane with
Flower-Like Microstructures for Photo-Induced Multi-Functional Protective
Clothing,"
Cellulose, 2018, 25, 481.9-30, doi 10.10071s10570-018-1881-5; Liu, Y., et al
"LIV
Crosslinked Solution Blown. PVDF Nanofiber Mats f.or Protective Applications,"
Fibers
Polym. 2020, 21, 489-97, doi: 10.10071s12221-020-9666-5.
NOM
To limit dermal exposure to airborne solid particles, health and safety
regulatory
agencies have published good practice guidelines, and wearing personal
protective equipment
(PPE) has been recommended to minimize exposure to a variety of hazards.
Chemical and
biological protective clothing (C.BPC.1) are widely used and are considered
the most economical
among PPE options. For airborne nanomaterials, type 5 CRPC is considered the
last line of
defense against such dangers, as it provides full body protection against
airborne solid
particulates according. to the ISO 13982-1 and ISO 13982-2 standards. See
International
Organization fOr Standardization (ISO) 13982-1:2004; International
Organization for
Standardization (ISO) 13982-2:2004.
100121
Nonwoven and woven materials commonly used as the base for type 5 CBPC
have
several disadvantages, such as poor permeability and filterability. See. e.g.,
Liu, Y., et al.,
supra; Wingert, L., et al. "Filtering Performances of 20 Protective Fabrics
Against Solid
Aerosols," J. Occup. Erwirort. Itig. 2019, 16, 592-606.
100131
Current commercially available facemasks and respirators either do not
have
adequate filtering efficiency to intercept the infectious particles or have
insufficient air
permeability to allow frequent and convenient. use.
Lee, S., et at 'Reusable
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PoiybenzimidazOie .Nanofiber Membrane Filter for Highly Breathable PM2.5 Dust
Proof
Mask," AG? App!. Mater. Intekfaees, 2019, 11, .2750-57,
doi:10,102.1/acsami.8b19741.
Moreover, the recent COVED-19 pandemic, has increased interest in antiviral
membrane
development for facemasks and respirators which will exterminate pathogens
contacting the
facemask or respirator. 'I'his will prevent infectious particles to be
transferred to another
surface by inadvertent, contact of the mask with other surfaces or by the
wearer touching the
exterior surface of the mask by hand.
I0014) Numerous antiviral agents are known that may be suitable
for use in coatings or
that may otherwise be integrated, into personal protective equipment. See,
e.g., Tran, DN., et
"Silver Nanoparticles as Potential Antiviral Agents against African Swine
Fever Virus,"
Mater. Res. &preys, 2020, 6(12), doi: 10.1088/2053-1591/ab6ad8; Moreno, MA.,
et al
"Active Properties of Edible Marine Polysaccharide-.Based Coatings Containing
Larrea "thick,
Polyphenols Enriched Extract," Food HydrocolL 2020. 102, 1055958 doi:
10.1016/j .foodhyd.2019.105595; Husen, A. "Naomi Product-Based Fabrication of
Zinc-
Oxide Nanoparticles and Their Applications," in .Netnontaterials and Plant
Potential, 2019,
193-219, Springer; Cheng. C., et al. "Functional Graphene. Nanomaterials
Based.
Architectures:Illiointeractions, Fabrications, and Emerging Biological
Applications," Chem.
Rev. 2017, 117, 1826-1914; Zhang, D.-h., et at "In Sine() Screening of Chinese
Herbal
Medicines with the Potential to Directly Inhibit 2019 Novel Coronavirus," I.
1ntegr. Med.
2020, 18, 1524, doi: 10.101641.jo1m.2020.02.005; U.S. Patent Nos. 9,963,611
and 8,678,002.
[00151 Widespread use of thcemasks, such as during the COVID-19
pandemic, has also
highlighted a need for transparent materials for producing .facemasks and
other personal
protective equipment. For example, children who are on the autism spectrum,
elderly persons
with limited hearing, and deaf-mute persons may have difficulty with
communication and
social interactions which do not allow such persons to observe facial
expressions and would
thereby significantly benefit from widespread use of transparent facemasks.
Transparent
facemasks would also be compatible with facial recognition technologies, such
as technologies
used for identity authentication. The use of nanofiber membranes also offers
promise in
addressing this need. See, e.g., Wang, C., etal. "Highly Transparent
Nanofibrous Membranes
Used as Transparent Masks for Efficient PMa3 Removal," ACS Maw, 2022, 16(1),
119-28;
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Xiao, Y., et at "Preparation and Applications of Electrospun Optically
Transparent Fibrous
Membrane,"Poolnerv, 2021, 13(4), 506.
[0016I Various techniques for producing nanofiber membranes are
known, including
electrospinning, phase inversion, interfacial polymerization, stretching, and
track-etching.
Electrospinning is a very useful technique that provides efficiency and
unitbrtnity of pore size.
See. e.gõ Ray, S.S., et al. "A Comprehensive Review: Electrospinning Technique
for
Fabrication and Surface Modification of Membranes for Water Treatment
Application," RSC
Adv. 2016,6(88), 85495-85514, doi: 10,1039/C6RA14952A. Electrospinning is a
process that
uses an electric field to generate continuous fibers on a micrometer or
nanometer scale.
Electrospinning enables direct control of the microstructure of a scaffold,
including
characteristics such as the fiber diameter, orientation, pore size, and
porosity.
[00171 Electrospun nanofibers have a wide range of applications.
These include
antibacterial food packaging, biomedical applications, and environmental
applications. See,
eg., Lh, E, et al. "Cold Plasma Treated Thyme Essential Oil/Silk Fibroin.
Nanofibers against
Salmonella Typhimurium in Poultry Meat," Food Packag. Shelf Life, 2019, 2.1,
100337; Zhu,
Y., et al. "A Novel Polyethylene. OxidelDendrobium eleinale Nanofiber:
Preparation,
Characterization and Application in Pork Packaging," Food Packag. Shelf Ly-
e.., 2019, 21,
100329; Surendhiran, D., et at "Encapsulation of .Phlorotatinin in
Alginate/PEO Blended
=Nanofibers to:Preserve Chicken Meat from Salmonella Contaminations," Food
Packag.. Shelf
Lffr, 2019, 21, 100346; Khan, M.Q., et al. "The Development of Nanofiber Tubes
Based on
Nanocomposites of Polyvinylpyrrolidone Incorporated Gold Nanoparticles as
Scull-bids for
Neuroscience Application in Axons," Teri. Res. .1. 2019, 89, 2713-20, doi:
10.1177/0040517518801185; 1.111ab, S., etal. "Antibacterial Properties of In
Situ and Surfice
Funetionalized Impregnation of Silver Sulfadiazine in Polyacrylonitrile
Nanofiber Mats," hit
J. Nanomedicine, 2019, 14, 2693-2703, doi: 10.2147/UN.S197665; Khan, M.Q., et
at
"Fabrication of Antibacterial Electrospun Cellulose Acetate/Silver-
Sulfadiazine .Nanofibers
Composites for Wound Dressings Applications," Polym. Test. 2019, 74, 39-44.
:Doi:
10. 10161 .polymertesti ng.2018.12.01.5; Ray, S.S., et al., supra.
100181 Electrospun nanofiber textiles have been considered
promising candidates for
CDPC.õ See, e.g., Lee, S., et al. "Transport Properties of Layered Fabric
Systems Based on.
Electrospun 1.1anofibers," Fibers Polym. 2007, 8, 501-06; Bagherzadeh, .R., et
al. "Transport
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Properties of Multi-Layer Fabric Based on Electrospun Nanofiber Mats as a
Breathable Barrier
Textile Material," Text. Res. J. 2012, 82, 70-76.
100191 Electrospun polymeric nanofibers may exhibit very high
external surface area,
excellent water vapor transport properties, and good mechanical strength. See.
e.g., Huang,
Z., et al. "A Review on Polymer Nartofibers by Electrospinning and Their
Applications in
Nanocomposites," Compos. Mama 2003, 63, 2223-53.
100201 Fabrication of textiles from electrospun polymeric
nanofibers generates ultra thin,
lightweight, and high tensile strength textiles. See. e.g., Lee, S., e at,
supra; Dhineshbabu,
N. R., et "Electrospun MgO/Nylon 6 Hybrid Nano fibers for Protective
Clothing," Nano-
Micro Lett. 2014, 6, 46-54; Han, Y., et al. "Reactivity and Reusability of
Immobilized Zinc
Oxide Nanoparticles in Fibers on Methyl Parathion Decontamination," 'Text.
Res. .7..2013, 86,
339-49.
100211 Electrostatic attraction causes small particles to be
attracted to nanofibers.
However, such electrostatic attraction tends to wear off relatively quickly.
Integrating
pt-inciples of electrostatic interaction with a triboelectric nanogenerator
(TING) may be used
to harvest mechanical energy from routine activities (e.g., respiration,
talking, making facial
expressions) and thereby generate charges on nanofiber filter media and
prolong the duration
of electrostatic attractions. This prolongs the useful life of filters that.
rely at least in part on
electrostatic attractions for filtration.
100221 Peng, et al. disclose a breathable, biodegradable,
antibacterial, and self-powered
electronic skin by sandwiching a silver nanowire electrode between a
polylactic-co-glycolic
acid (PLGA) niboelectric layer and a polyvinyl .alcohol (PVA) substrate. Peng,
X, et al. "A
Breathable, Biodegradable, Antibacterial, and Self-Powered Electronic Skin
Based on All-
Nanofiber Triboelectrie Natiogenerators," Sc!. Adv. 2020, 6(26), eaba9624.
100231 Sun, et at disclose an all-fiber breathable and waterproof
wearable device with a
multilayer structure consisting of a PA66/carbon nanotubes nanofiber layer, a
poly (vinybdene
fluoride) (PV.DF) layer, and a conductive fabric layer. Sun, N., et al.
"Waterproof, Breathable
and Washable Triboelectrie Nanogenerator Based on Electrospun =Nanoliber Films
fOr
Wearable Electronics," Nano Energy, 2021, 90, 106639.
10024) Jiang, et al. disclose electrospinning nanofibers to
develop a multifunctional all-
nanofiber-based TING with UV-protective, water-repellent, antibacterial, self-
cleaning, and
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self-powered properties. Jiang, Y., et at "UV-Protective, Self-Cleaning, and
Antibacterial
Nanofiber-Based Triboelectric Nanogenerators for Self-Powered Human Motion
Monitoring,"
ACSAppl. Mater. Wet:Awes, 2021,13(9), 11.205-14.
100251
Chen, e at disclose functionalized nanofiber mats generated by
integrating
nucleophilic oxime moieties through electrospirming of polyacrylamidoxime
(PA.A0) and
PAN. These functionaiized nanofiber mas exhibited a substantial ability to
hydrolyze chemical
nerve agents. Chen, L., et at "Multifunctional Electrospun Fabrics via Layer-
by-Layer
Electrostatic Assembly for Chemical and Biological Protection," Chem. Maier.
2010, 22,
1429-36.
100261
Choi, et at disclose fabricated polyurethane nanofibers functionalized
by N-chloro
hydantoin (NCH-PLI). These nanofibers suecessfully decontaminated a simulant
for V-type
nerve gas (demeton-S-methyl).Choi, j., et at, "N-Chloro Elydantoin
Functionalized
Polyurethane Fibers Toward Protective Cloth Against Chemical Warfare Agents,"
Polymer,
2018, 138, .146-55.
100271
Various metal nanoparticles integrated nanofibers have been disclosed
that have
been proposed for use in protective clothing and face masks for shielding
against harmful
chemicals and biological agents. See, e.g., Ramaseshan, R., et al. "Zinc
Titanate ofibers
for the Detoxification of Chemical Warfare Simulants, J. Am. Ceram. Sac, 2007,
90, 1836-42.
100281
Lee, etal. disclose functional PAN nanofiber webs to protect users from
a simulant
of a chemical warfare. agent (CWA). Lee, J., ei al. "Preparation of Non-Woven
Nanofiber
Webs for Detoxifieation of Nerve Gases," Polymer, 2019,179, 121664.
100291
Zhao, et al. disclose metal--organie frameworks (MOB) integrated into
polyamide-
6 nanotibers. The MOF-nanofiber composites exhibited extraordinary reactivity
tbr
detoxifying CWAs. Zhao, L, et al. "Ultra-Fast Degradation of Chemical Warfare
Agents
Using MOF--Nanofiber Kebabs," Angew. Chem. In!, Ed. 2016 55, 13224-28.
100301
Zhao, et at disclose a step-by-step dip-coating and heat curing method
of
fabricating fluorine-free, efficient, and biodegradable waterproof and
breathable menibnuies.
Zhao, .1., et a/. "Fluorine-Free Waterborne Coating for Environmentally
Friendly, Robustly
Water-Resistant, and. Highly Breathable Fibrous Textiles," ACS Nano, 2020,
14(1), 1045-54.
100311
Mang, eta!, disclose a moisture pump with multilayer wood-like cellular
networks
and interconnected open Channels based on an electrospun nanofibrous membrane
for solar-
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driven continuous indoor dehumidification. Zhang, Y., et al., "Super
Hygroscopic
Nanofibrous Membrane-Based Moisture Pump for Solar-Driven Indoor
Dehumidification,"
Nat. Commun, 2020, I ), 3.302-
100321 On account of challenges related to scale-up of nanofiber
production processes,
nanofiber-based air filters are still currently rare. Thus, it remains a need
to develop a sealable
nanofiber platform to produce nanofiber membranes for use in air filtration
applications.
SUMMARY
100331 An electrospun polymer mmofibrous membrane that provides
high filtering
efficiency and excellent porosity is disclosed. herein.
100341 The membrane may be treated with one or more antimicrobial
or antiviral agents.
In some embodiments, the membrane may be treated with an antiviral agent
selected from the
group consisting of graphene, nanoparticles, nanocomposites; multivalent
metallic ions, and
medicinal or other extracts from natural products. The treatment may
preferably be a coating
of one or more antiviral agents on the surface of the membrane. Alternatively,
one or more
antiviral agents may be impregnated into the nanofibrous membrane.
100351 The membrane may additionally or alternatively be
impregnated with one or more
metal-organic frameworks (MOFs). The one or more MOT's may, for example, be
one or more
zirconium MOFs. The MOFs may provide filtration of chemical warfare agents
(CWAs) and
other toxic chemical agents and, in some embodiments, may also provide
additional or
alternate filtration of small particulates and pathogens.
100361 The membrane may additionally or alternatively incorporate
one or more
photocatalytie agents for the removal of volatile organic compounds (VOC:s).
100371 The disclosed membrane may preferably have a high
filtering efficiency.
(00381 In some embodiments, the porosity of the disclosed
membrane may be sufficient to
provide breathability characteristics suitable for use as a facemask or
respirator. The disclosed
membrane is suitable for use in making facemasks and respirators that are
highly resistant to
infectious pathogens and/or other small particulates.
100391 In some embodiments, the disclosed membrane may be
suitable for use in making
air filters for use in indoor air filtration applications, such as use in air
filters for II VAC
systems.
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100401 In some embodiments, the disclosed metribrane may be used
in conjunction with a
separate membrane that facilitates removal of carbon dioxide, such as a carbon
nanofiber
membrane.
100411 in some embodiments, the disclosed membrane may be
substantially transparent.
BRIEF DESCRIPTION OF THE DRAWINGS
100421 FIG. I shows representative scanning electron microscopy
(SEM) images of
embodiments of the disclosed nanofibrous polymer membranes.
100431 FIG. 2 shows fiber diameter measurements and distribution
for .representative
samples of an embodiment of the disclosed .nanofibrous polymer membrane.
100441 FIG:3 shows pore size distribution for representative
samples of an embodiment
of the disclosed nanofibrous polymer membrane as determined by mercury
porosimeter
analysis.
100451 FIG. 4 shows average porosity and the distribution of mean
porosity for
representative samples of an embodiment of the disclosed nanofibrous polymer
membrane.
100461 FIG. 5 shows mechanical tensile strength test results for
representative samples of
an embodiment of the disclosed nanofibrous polymer membrane.
100471 FIG. 6 shows filtration efficiency test. results for
representative samples of an
embodiment of the disclosed nanofibrous polymer membrane..
100481 FIG. 7 shows latex filtration test results for
representative samples of an
embodiment of the disclosed nanofibrous polymer membrane.
100491 FIG. 8 shows viral filtration efficiency test results for
representative samples of an
embodiment of the disclosed nanofibrous polymer membrane.
100501 FIG. 9 shows bacteria filtration efficiency test results
for representative samples of
an embodiment of' the disclosed nanofibrous polymer membrane.
100511 FM. 10 shows flammability test results for a
representative sample of an.
embodiment of the disclosed nanofibrous polymer membrane.
100521 FIG. 11 shows antiviral properties test results for
representative samples of an
embodiment of the disclosed nanofibrous polymer membrane.
100531 FIG. 12 shows antibacterial properties test results fbr
representative samples of an.
embodiment of the disclosed nanofibrous polymer membrane.
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100541 FIG. 13 shows how filtration efficiency is affected by the
flow rate of aerosols
through the membrane.
[00551 FIG. 14 shows how the pressure drop across the membrane is
affected by the flow
rate of aerosols through the membrane.
100561 FIG. 15 shows an embodiment of a system for removing
volatile organic
compounds and carbon dioxide.
100571 FIG. 16 shows the basic repeat units of rectangular.
hexagonal, and triftexagonal
opening patterns for mesh substrates.
100581 FIG. 17 shows a. schematic representation or a. flexible,
breathable, and
antimicrobial facemask based on an alkianoliber TEN() (NF-TING) platform.
DETAILED DESCRIPTION
[00591 An electrospun polymer nanofibrous membrane that provides
high filtering
efficiency and excellent porosity is disclosed' herein.
100601 The membrane may be treated with one or more antimicrobial
or antiviral agents.
In some embodiments, the membrane may be treated with an antiviral agent
selected from the
group consisting of graphene, nanoparticles, nanocomposites, multivalent
metallic ions, and
medicinal or other extracts from natural products. The treatment may
preferably be a coating
of one or more antiviral agents on the surface of the membrane. Alternatively,
one or more
antiviral agents may be impregnated into the nanofibrom membrane.
[00611 The membrane may additionally or alternatively be
impregnated with one or more
metal-organic frameworks (MOB). The one or more MOFs may, for example, be one
or more
zirconium IVIOFs. The MOFs may provide filtration of chemical warfare agents
(CWAs) and
other toxic chemical agents and, in some embodiments, may also provide
additional or
alternate filtration of small particulates and pathogens.
100621 The membrane may additionally or alternatively incorporate
:one or more
photocatalytic agents for the removal of volatile organic compounds (VOCs).
100631 The disclosed membrane may preferably have a high
filtering efficiency.
[00641 In some embodiments, the porosity of the disclosed
membrane may be sufficient to
provide breathability characteristics suitable for use as a facemask or
respirator. The disclosed
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membrane is suitable for use in making facemasks and respirators that are
highly resistant to
infectious pathogens and/or other small particulates.
100651 in. some embodiments, the disclosed membrane may be
suitable for use in making
air filters for use in indoor air filtration applications, such as use in air
filters for HVAC
systems.
100661 In some embodiments, the disclosed membrane may be used in
conjunction with a
separate membrane that facilitates removal of carbon dioxide, such as a.
carbon nanofiber
membrane.
100671 The disclosed membrane may preferably have a filtering
efficiency of at least 95%,
more preferably at least 98%, even more preferably at least 99%, and most
preferably at least
99.5%.
100681 in some embodiments, the disclosed membrane may be
substantially transparent.
The transparency may preferably be at least 80%.
100691 The disclosed membrane may preferably be capable of
intercepting and
exterminating infectious pathogens on its surfaces.
100701 In some preferred embodiments, the disclosed membrane is
non-flammable.
100711 The disclosed membrane may be suitable for the production
a non-flammable
high-performance textiles.
100721 In some preferred embodiments, the disclosed membrane is
ultrathin and
lightweight.
100731 in some preferred embodiments, the disclosed membrane does
not degrade upon.
exposure to water or selected organic solvents such as ethanol or acetone.
Thus, products:made
using the membrane may be washed and reused.
100741 In some embodiments, the nanofibrous polymer membrane may
be made. fr01.11
.polyvinylidene. fluoride (PVDP). In some alternate embodiments, the
nanofibrous polymer
membrane may be made from one or more Tecophiliem thermoplastic polyurethanes
(711>1.is).
In other alternate embodiments, the nanofibrous polymer membrane may be made
from one or
more polyeaprolactams. in some additional alternate embodiments, the
nanofibrous polymer
membrane may be made from polyvinylpyrrolidone (PVP). In some additional
alternate
embodiments, the nanofibrous polymer membrane may be made from
poly(vinyliderte
fluoride-co-hexafluoro propylene) (PVDF-HFP). In some additional alternate
embodiments.
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the nanofibrous polymer membrane may be made from polylactic acid (PIA). In
some other
alternate embodiments, the nanofibrous polymer membrane may be made from a
blend of two
or more of polyvinylidene fluoride, one or more Tecophilierm thermoplastic
polyurethanes,
one or more polycaprolactams, polyvinylpyrrolidone, poly(vinylidene fluoride-
co-hexafluoro
propylene), and polylactic acid.
100751 'the nanofibrous polymer membrane may be made using
electrospinning
techniques. .A polymer is dissolved in a solvent prior to electrospinning. In
some
embodiments, the solvent may preferably be selected from the group consisting
of
dimethyllonnamide (DMI7), dimethylacetamide (DMA), ethanol, hexa
fluoroisopropanol
(IMP), acetone, ethyl acetate, dichloromethane (DCNI), formic acid, water, or
a combination
thereof. In some preferred embodiments, the solvent may be
hexafluoroisopropanol (11FIP).
[00761 In some embodiments, a surfactant may be added to the
polymer solution. .Adding
a surfactant to the polymer solution may promote a smaller fiber diameter and
thus yield a
membrane which has a smaller pore size and thus higher filtration efficiency.
En some
preferred embodiments, the surfactant may be one or more surfactants selected
from the group
consisting of cetrimonium bromide (CTAB), lauramidopropyl betaine (LAPB), and
alpha.
olefin sulfonate (AOS).
100771 In some embodiments, a salt or salt solution may be added
to the polymer solution.
Adding a salt or salt solution to the polymer solution. may promote formation
of thinner and
more uniform fibers, may reduce bead formation, and/or may increase branching
within the
fibers. By increasing charge density and conductivity, the presence of salts
in the polymer
solution. promotes elongation of the spinning jet, which leads to the
generation of thinner fibers.
In some preferred embodiments, the salt or salt solution may be one or more
salts or salt
solutions selected from the group consisting of alkali metal halides,
substituted or unsubstituted
ammonium halides, and phosphate-buffered saline (PBS). In some more preferred
embodiments, the salt or salt solution may be one or more salts selected from
the. group
consisting of sodium chloride (NaCI), lithium chloride (Lin), and potassium
chloride (KCI).
100781 The nanofibrous polymer membrane may be a single layer
membrane or may
alternatively be an integrated multi-layer membrane. In some embodiments, the
membrane
may be composed of multiple integrated layers with distinguishable
microstructure
characteristics. .A membrane that is composed of multiple integrated layers
may provide
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enhanced .filtration efficiency and low airflow resistance. Low airflow
resistance corresponds
to high breathability in applications where this is relevant. The enhanced
filtration efficiency
of an integrated multi-layer membrane may result from superior barrier
protection against
small pathogen particles and small diameter particulate matter.
100791 In some embodiments, the integrated multi-layer membrane
is composed Of two
layers with different pore sizes. In some alternate embodiments, the
integrated multi-layer
membrane is composed of three layers with two layers of equal pore size
separated by a layer
with a different pore size. The pore size may preferably be between 1 and 20
inn for the
layer(s) with smaller pore size and between 20 and 200 pm for the layer(s)
with larger pore
size.
100801 In embodiments with three layers having two layers of
equal pore sizesepanited by
a layer with a different pore size, the layers of equal size may preferably
have a larger pore
size and the layer in between these two layers may preferably have a smaller
pore Size. This
configuration decreases the likelihood of delamination, and also decreases the
pressure drop
that is generated as a gas passes through the multi-layer membrane, which
corresponds to
increased breathability, without appreciably reducing the -filtration
efficiency of the membrane.
1001411 In some other alternate embodiments, the integrated multi-
layer membrane is
composed of three layers with three different pore sizes.
100821 The pore size of the layers in integrated multi-layer
membranes may he adjusted by
adjusting the viscosity of the polymer solution and the eleetrospinning
process conditions.
I?Jectrospiiming process conditions may be adjusted to further stabilize the
spinning jet used in
the electrospinning setup. Solutions with lower viscosity will, typically
generate smaller pore.
size layers, and solutions with higher viscosity will typically generate
larger pore size layers.
100831 in some embodiments, the mechanical integrity and binding
forces between layers
of the membrane may be enhanced by electrospraying short fibers prior to
electrospitming the
subsequent layer. In some other embodiments, the mechanical integrity and
binding forces
between layers of the membrane may be enhanced by electrospirming wet fibers
by decreasing
the screen distance to generate a "tacky surface" prior to electmspinning the
subsequent layer.
100841 In some embodiments, the disclosed nanofibrous polymer
membrane may be
Laminated onto a textile material. Alternatively, the nanofibers may be
directly electrospun on.
nonwoven fabrics such as polyethylene terephthalate.(PE1), polypropylene (PP),
.polyamides
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such as PA6, PET copolymers, and spunbond Rico materials. Transparent nonwoven
-fabrics
may be used for applications where transparency of the. electrospun
nanofibrous polymer
membranes is desirable. The use of .Pla copolymers or spunbond Bico materials
results in.
enhanced adhesion between the nanofibers and textile, which thereby reduces
peeling.
100851 In some embodiments, the disclOsed nanofibrous polymer
membrane is directly
electrospun onto a. mesh substrate. The mesh substrate may have an opening
pattern
specifically designed to be suitable for eleetrospinning nanofibers thereon.
The opening
'pattern of the mesh substrate may, for example, be a: rectangular, hexagonal,
or trihexagonal
opening pattern, as shown in FIG. 16. Electrospinning onto a mesh substrate
may allow the
production of a transparent or substantially transparent nanofibrous polymer
membrane.
100861 In some embodiments, the disclosed nanofibrous polymer
membrane is
triboelectrically charged using a triboelectric nanogenerator (TENG). This
yields a membrane
that is self-charging. In some embodiments, the nanofibrous tribo-negative
layer may be
composed of polyvinylidene fluoride (1)VDF). In some embodiments, the
nanofibrous tribo-
positive layer may be composed of polyamide (PA66) nanofibers.
100871 In some embodiments, the conductive electrode layer may be
composed of a
polypyrrole-coated nanofibrous membrane. In some alternate embodiments, the
conductive
electrode layer may be composed of silver nanofibers. In some other alternate
embodiments,
the conductive electrode layer may be composed of conductive fabrics
100881 In some, embodiments, a cellulose-based adhesive is
applied to an electrospinning
substrate prior to electrospioning to enhance the mechanical integrity of the
nanofibrous
membrane layers under high air flow conditions.
100891 In some embodiments, a polyvinylacetate (PVAc) layer is
electmspun onto an
electrospinning substrate at the same time as electrospinnhig of the target
polymer:
100901 The disclosed nanofibrous polymer membrane may be treated
with an anti-
pathogenic agent such as an antiviral agent selected from the group consisting
of graphene,
nanoparticles, nanocoMposites, multivalent metallic ions, and medicinal or
other extracts from
natural products. The graphene may be functionalized or non-functionalized.
The
nanoparticles may preferably be metal nanopartieles such as silver
nanopartieles or zinc
nanoparticles. The nanocomposites may preferably be silver-doped titanium
dioxide
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nanomaterials, 'Ile multivalent metallic ions may preferably be metal ions
such as eu2* or
Zn2''' cations. The extracts from natural products may preferably be licorice
extracts.
[00911 The anti-pthogenic agent(s) may be physically coated on
the surface of the
membrane. The coating may be applied using chemical or electrochemical methods
such as
atomic layer deposition, vapor deposition methods such as physical vapor
deposition (PVD)
or chemical vapor deposition (CM, spray coating methods such as plasma
spraying or spray
painting, or physical coating methods such dip-coating Or spin-coating.
100921 The anti-pathogenic agent(s) may alternatively be
incorporated into the membrane
by blending the anti-pathogenic agent(s) into the polymer solution prior to
electrospinning,
thereby generating a membrane impregnated with the. anti-pathogenic agent(s).
100931 In some embodiments, the disclosed nanofibrous polymer
membrane may be
Impregnated with one or more metal-organic frameworks (MOFs), such as
zirconium MOFs.
The MOFs may be incorporated into the membrane by blending the .MOFs into the
polymer
solution prior to electrospinning, thereby generating a membrane impregnated
with the MON.
100941 In some embodiments, MOF-impregnation into the membrane
may be in addition
to coating with or impregnation of anti-pathogenic agent(s). In other
embodiments, MOF-
impregnation into the membrane may be an alternative to coating with or
impregnation of anti-
pathogenic agent(s). Membranes impregnated with MOFs may provide filtration of
chemical
warfare agents (CWAs) and other toxic chemical agents. In some embodiments,
membranes
impregnated with MOFs may also exhibit antiviral, antibacterial, or other anti-
pathogenic
properties.
100951 Thus, it is not intended that the MOB described herein are
necessarily distinct from
the anti-pathogenic agents, such as antiviral or antibacterial agents,
described herein. Rather,
the anti-pathogenic agent may be a MOF or may alternatively be one of the
other anti-
pathogenic agents described herein. It is also not intended that the MOFs
described herein will
necessarily exhibit antiviral, antibacterial, mother anti-pathogenic
properties. MOFs that are
impregnated in the disclosed membranes may provide filtration of chemical
warfare agents
(MAO and other toxic chemical agents but,. in some embodiments, may not
exhibit antiviral,
antibacterial, or other anti-pathogenic properties or provide filtration of
small particulates.
100961 In some embodiments, the disclosed nanofibrous polymer
membrane may be
impregnated with one or more photocatalysts, such as Ti02, N-doped 1'i02, Ag-
doped =T102,
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or A1203-1102. The photocatalyst may be incorporated into the membrane by
blending the
photocatalyst into the polymer solution prior to electrospinning, thereby
generating a
membrane impregnated with the photocatalyst.
100971 in some embodiments, photocatalyst-impregnation into the
membrane may be in
addition to coating with or impregnation of anti-pathogenic agent(s). In other
embodiments.
photocatalyst-impregnation into the membrane may be an alternative to coating
with or
impregnation of anti-pathogenic agent(s). Membranes impregnated with
photocatalysts may
facilitate degradation of VOCs. In some embodiments, membranes impregnated,
with
photocatalysts may also exhibit antiviral, antibacterial, or other anti-
pathogenic properties.
100981 Thus, it is not intended that the. photocatalysts
described herein are necessarily
distinct from the anti-pathogenic agents, such as antiviral or antibacterial
agents, described
herein. Rather, the anti-pathogenic agent may be a photocatalyst or may
alternatively be one
of the other anti-pathogenic agents described herein. It is also not intended
that the
photocatalysts described herein will, necessarily exhibit antiviral,
antibacterial, or other anti-
pathogenic properties. Photocatalysts that are impregnated in the disclosed
membranes may
facilitate degradation of VOC.'s but, in some embodiments, may not. exhibit
antiviral,
antibacterial, or other anti-pathogenic properties.
100991 In some embodiments, the photocatalyst-impregnated
nanofibrous polymer
membrane may be used in conjunction with a carbon nanofiber (CNF) membrane for
removal
of CO2. In some alternate embodiments, themembrane may have one or more
photocatalyst-
impregnated layers and one or more CNIF layers.
101001 The photocatalyst-impregnated membrane preferably exhibits
high filtration
efficiency, thermal insulation, and photodegradation capability, and allows
tor efficient VOC
degradation and small particle filtration. The use of an additional esIF
membrane in the system
allows effective in situ CO2 capture. during pbotocatalytic degradation. The
rate of VOC
degradation is preferably greater than 95%, and the CO2 adsorption rate is
preferably greater
than 20 mmollm2s.
101.011 In some embodiments, .a yttria-stabilized zirconia (VSZ) I
silica nanolibrous
membrane may be additionally or alternatively be used in the applications
described herein,
particularly in. applications that include photocatalytic removal of VOCs.
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101.021 To increase the breathability of textile materials coated
with the disclosed
nanofibrous polymer membranes, multiple nanofiber layers of differing
thicknesses may be
electrospun on the same or opposite sides of .textile materials. A. textile
material that is in the
form of a textile material roll may be coated with one or more nanofiber
layers by
electrospirming. In some embodiments, one or more first nanofiber layers are
electrospun on
a first side of a textile material at a first winding speed, the textile
material roll is flipped, and
one or more second nanofiber layers are eleetrospun on a second side of the
textile material at
a second winding speed, where the first winding speed is different from the
second winding
speed. In other embodiments, one or more first nanofiber layers are
electrospun on a first, side
of a textile material at a first winding speed, and one or more second
nanofiber layers are then
electrospun on the first side of the textile material at a second winding
speed, where the first
winding speed is different from. the second winding speed. In yet other
embodiments, one or
more first nanofiber layers are electrospun on a first side of a textile
material at a first winding
speed, one or more Second nanofiber layers are then electrospun on the first
side of the textile
material at a second winding speed, the textile material roll is then flipped,
and one or more
third nanotiber layers are electrospun on a second side of the textile
material at a third winding
speed., where the first winding speed is different from the second winding
speed. in yet other
embodiments, additional elmtrospinning steps may be added to include
additional nanofiber
layers of different thicknesses on one or both sides Odle textile material.
101031 A facemask or respirator made from the disclosed
nanofibrous polymer membrane
is also disclosed. herein. The facemask or respirator may preferably have a
.high filtration.
capacity and suitable breathability characteristics for comfortable use by a
wearer. The
disclosed facemask or respirator may preferably have a filtering efficiency of
at least 95%,
more preferably at least 98%, even more preferably at least 99%, and most
preferably at least
99.9%.
101041 In. some embodiments, a facemask made from the disclosed
nanofibrous polymer
membrane is a flexible, breathable, and antimicrobial facemask based on an all-
nanoliber
TUNG (417-TENG) platffirm. In some embodiments, the facemask comprises
multiple layers.
In some embodiments, the muitilayer facemask. includes a tribo-positive layer
of polyamide
(PA66) nanofibers, a tribe-negative layer of poly (vinylidene fluoride) (INDY)
nanofibers, and
a conductive electrode layer with polypyTrole, silver nanowires, or a
conductive fabric.
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101.051 A method of making a facemask or respirator from the
disclosed nanofibrous
polymer membrane is also disclosed. herein. The method may preferably allow
the anti-
pathogenic, physical, chemical, and mechanical properties to be fine4uned
according to the
requirements of the specific application.
101.061 A method of making an air filter fbr use in an HVAC system
from the disclosed
nanofihrous polymer membrane is also disclosed herein.
101071 A method of making an air filter for use in the removal of
VOC:s and COz from the
disclosed nanofibrous polymer membrane and a carbon nanoliber membrane is also
disclosed
herein.
Sample Prei ation
[0108] The following sample preparation materials and methods are
exemplary. Other
suitable materials and methods may be used within the scope of the invention.
[01.091 Materials. Multiple Tecophilierm thermoplastic
polyurethanes (Tpu) were
purchased from Lubrizol. Knyar 2801 .polyvinylidene fluoride (PVD17) was
purchased from
Arkema. Zytel 7301 polycaprolactam was provided by DuPont.
Hexafluoroisopropartol
(11FIP) was purchased fmm Oakwood Products Inc. Dimethylacetamide (DMAc),
acetone,
formic acid, eetrimonium bromide (CTAB), lithium chloride (LICI), and
tetrabutylammonium
chloride (TBAC) were purchased from Fisher Scientific. Silver nanoparteies (15
tim) were
purchased from Skyspring Nanomaterials. ZnO and Cut) (Zn-Cu) were purchased
from Sigma
Aldrich. A.g-doped TiO2 (Ag-T102).nanoparticles were provided by IM Material
Technology
Inc. Licorice extracts were provided by XSI., USA Inc.
[01.101 Solution Preparation. TP1.1 polymers were added to IMP to
create 7 and 15 w/v
solutions. 16.5% wt MTH: was dissolved in 3:1 DivlAc/acetone containing 0.85%
CTAB and
0.04% Lia, Nan, or TBAC. All of the solutions were mixed on a stirring plate
until the
polymer pellets/powder completely dissolved.
[01111 Antiviral Treatment. Two antiviral treatment methods were
used: (I) the
membranes were submerged in an aqueous dispersion containing antiviral
particles, or (2) the
antiviral agents were added to the polymer solutions to directly fabricate
antiviral nanofibrous
membranes. The antiviral agents used. were 2% citric acid and silver. Ag-1102
and Zn-Cu
nanoparticles, and licorice extracts.
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101.121 Membrane Fabrication. The membrane fabrication process was
a roll-to-roll
system, where a textilematerial was wound from one side to the other side and
the nanofiber
layer was laminated on the textile during thewinding process. The thickness of
the nanofiber
layers was controlled by controlling the winding speed.
101131 The eleetrospinning process was performed in a single step
or alternatively in at
least three separate steps.
101141 In the one-step process, one syringe was tilled with a
polyvinylacetate (PVAC)
solution and one or more additional syringes were filled with the target
polymer solution. The
PVAc and target polymer solutions were electrospun simultaneously. The
layereontacting the
substrate was formed of .VVAc and thereby provided increased adhesion between
the substrate
and the rianolibrous membrane layers.
101151 in the three-step process, the substrate was first coated
with a celhdose-based
adhesive using a sponge coating process. Then electrospun nanofibers were
coated onto the
substrate. Finally, the -coated substrates were dried by heating.
1011.61 Funetionalization. The membrane was functionalized either
by adding the desired
ftwictionalizing agents to the electrospinning solution or by suspending the
electrospun
membrane in a dispersion of the desired timetionalizing agent in a solvent,
such as 2%
zirconium MOF, 2% citric acid and silver, Ag-TiO2, ZnO or CuO nanoparticles,
or licorice
extract.
101171 Photacatalyst-Impregnated Membrane Preparation. A
photocatalyst precursor
is prepared with 2.5 ml. of a 1-100 mglml, solution of a .photocatalytie
material or
photocatalytic material precursor selected from. the group consisting of
titanium
tetraisopropoxide. Al(acae)3, and AgNO3, 0.3 g of a surfactant selected from
the. group
consisting of polyvinylpyrrolidone (I)VP), laniumidopropyl betaine (LAPB),
alpha olefin
sulfonate (AOS), and cetrimonium bromide (CTAB), 4.5 rid. of ethanol, and 3.0
triL of acetic
acid. The solution is subsequently stirred ma stirring plate for over 12 h.
101181 Nanofibers carriers for the photocatalyst are fabricated
using an electrospinning
apparatus. The process parameters used for elect-rot:pinning are a -now rate
of 0.5 MLA, a
vertical distance from the needle to grounded aluminum foil of 10-15 cm, and
an applied
voltage of 15-20 kV. The electrospun nanofibers are calcined at 600 C for 2 h
in air, with a
ramping rate of 1-3 Cimin.
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101.191 The nanofiber carriers are submerged in the prepared
photocatalyst precursor for 5
min under vacuum and then rinsed thrice with 2-propanol. The photocatalyst-
impregnated
nanofibers are dried overnight under ambient conditions, and are then calcined
at 500 C for I
h in air, with a ramping rate of 5 C/min.
101201 Carbon Nenonber Membrane Preparation. A carbon nano tiber
membrane is
prepared by treating an eletrospun nanotiber mat. The prepared eletrospun
nanofiber mat is
chemically dehydrofluorinated at 70 '3C for I h in a 4 M aqueous NaOH solution
containing
12.5 m.M of tetrabutylammonium bromide (TBAB). After chemical
dehydrofluorination is
complete, the mat is washed with water and ethanol several times, and is then
dried under
reduced pressure at 60 'C. Finally, the mat is treated by a carbonization
process: the mat is
heated at a rate of 3 C /min up to 1000 C. under an argon atmosphere and
maintained at this
temperature for 1 h.
Characterization of Representative Samples
101.211 To investigate the feasibility of using the disclosed
nanofibrous polymer
membranes in tacemasks and respirators or in HVAC or other air filtration
applications, the
morphology, fiber diameter, filtering efficiency, porosity, wettability,
mechanical strength, and
optionally antiviral activity and particulate-retention capacity of
representative samples of
embodiments of the disclosed nanofibrous polymer membrane were characterized.
101221 Nanofibrous polymer membranes were characterized using
scanning electron
microscopy (SEM) imaging. FIG. 1 shows representative SEM images of an
embodiment of
the disclosed nanofibrous polymer membrane. The larger images show 2000X
magnification,
while each inset shows the respective 5000X magnification image. As shown in
FIG. I , the
internal and external surfaces of each nanofiber membrane display consistent
morphology
between samples. In addition, the nanofibrous membranes show good orientation
and are free
of breading, splitting, and other undesirable morphological features.
Rani FIG. 2 shows fiber diameter measurements and distribution
for representative
samples of an embodiment of the disclosed nanofibrous polymer membrane. The
average fiber
diameter of representative samples was 0.224 m, with a median fiber diameter
of 0.210
and a standard deviation of 0.106. The average orientation was 79 , and the
area coverage was
16%.
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101.241 FIG. 3 shows pore size distribution for representative
samples of an embodiment
of the disclosed nanotibrous polymer membrane as determined by mercury
porosimeter
analysis. The mean pore diameter was tbund to be 0.0025 um.
101251 Fla 4 shows average porosity and the distribution of mean
porosity for
representative samples of an embodiment of the disclosed nanolibrous polymer
membrane.
The average porosity as determined by gravimetxic measurements was shown to be
distributed
around a center point of 78.5%. As shown in FIG. 4, all samples showed
consistent porosity
in the range of 75% to 83%. :High porosity of the membrane is a critical
requirement to increase
the breathability of a ficemask or filter made from the membrane.
191.261 FIG. 5 shows mechanical tensile strength test results for
representative samples of
an embodiment of the disclosed nanofibrous polymer membrane.
101271 A representative sample of an embodiment of the disclosed
nanofibrous polymer
membrane was also tested for filtration efficiency. The observed efficiency
was 99.61% for
30 Umin, with a pressure loss of 1.265 mbar, and 99.85% for 95 Limin, with a
pressure loss
of 4.3 Mbar.
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101281 Table I shows a summary of test results for representative
samples of an
embodiment of the membrane.
TABLE 1
Laboratory Test Standard Results
ATI International Filtration Efficiency >99% mean
filtration effieleney
Nelson Labs Synthetic Blood Penetnition ASTM F2100 no
penetration
Nelson Labs Flammability Test A: .. . ..
FM P101 Class I
= .
Nelson Labs CytOtoxieity ASTM F7 102 Grade 0
Nelson Labs Particle: Fiftra. tin*Elficiency .ASTKE7.103
average 99%
Nel3CM Labs Virus Filtration Efficiency ASTM F2104 average
99.5%
Nelson Labs Bacterial filtration Efficiency ASTM 12105
average. 99.5%
MicroChem MS2 .Bacteriophage AATCC 100 >99% reduction
-.MititChem .:-Hurrian Comnavirus 221E: AATCC:100- -
99.9%reduction
=
Mairegenix E con ASTM E23 IS >99.9%
reduction
:MWegettis -,C114)1 eritivirtis . . >90%
reducti0o,
: =
SEM
fiber diameter analysis
Matregenix Membrane Microstructure NIA
porosity measurements
contact angle measurements
101291 Representative samples of an embodiment of the membrane
did not degrade after
washing with water or ethanol. By contrast; a sample of a melt-blown membrane
showed a
significant decrease in filtration efficiency Wier washing with ethanol.
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101301 A comparison between. a representative sample of an
embodiment of the disclosed
nanotibrous polymer membrane and a typical melt-blown membrane is shown in
Table 2.
TABLE 2
Parameter Melt-Blown Membrane Nanorther
Membrane
Thickness (s.,,sn) 35
0.8
Fil.-)er Diameter (lim't
Ø15
Pt;re Size 6
0,05
Filtratim " (7)5 , õ
Etrielcitcy
944
Witter \ .1-rinrnission Rate (WVTR) 142
155
WL Contact Angie (') 19
.153
Cytocompatibility 105
155
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101311 The filtration efficiency and observed pressure drop for
various membrane samples
for use in personal protective equipment applications is shown in Table 3.
TABLE 3
Sample No. Flow Rate (Limit') Filtration Efficiency (*Ai)
Pressure Drop
(mm wg)
9F-1:17 85 : 97:1Q: :
1.3.8:
QF-104 85 99.58
20.8
Q17-105 85 99.02
. . . . :
OF-108 85 99.49
18.9
:
!IV1Xf011 .20:: :::: : 91$0 x...o : !
! : : '.
: : :
MXF011 32 98.10
4.6
..
, :..MX F011 ::::60: 98.46
:8:8
,
MXF011 80 97.16
11.8
14)0011 :100 0.7:45
10.j.]:
MX1012 20 98.57
2.9
MX 12 ::$2. =:9716
MXF012 60 97.65
8.9
101XF012 ::40 91:789 ;
:12 I:
.MXF012 100 98.18
16.6
i:::::::::::::::::::::::::::::::::::::::2::::::::
::MXF013 :"20 6i 95, I:
:::2:4 1
141XFO IS 32 96.22
4.0
.:::::::::::
NIVQ13 60 9198:
8.6
: , ,
114XF013 80 97.62
.11.8
NIXF013 100 96;0
154!
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101321
The filtration efficiency and observed pressure drop for various
membrane samples
for use in IIVAC applications is shown in Table 4.
TABLE 4
Flow
Filtration Pressure Filtration Pressure
Sample
Rate Substrate Efficiency Drop E
No. fliciency
Drop
(L/min) (/e) (rim wg) (%)
(mm wg)
cfM,949.- 325. :97000:: .20 70:
0.40
-
QIN1-081 32.5 978/ I 00 20 0.2 66
0.30
=
QIM OM
3.15, ,:s.71V10(J ===*: 77
050
QFM-085 32.5 778/70G 20 0.2 72
0.35
101331
FIGs. 6-12 show test results ibr filtration efficiency, flammability,
and antiviral and
antimicrobial properties for representative samples of an embodiment of the
disclosed
nanolibrous polymer membrane intended for use in personal protective equipment
applications.
[01341
FIG. 13 shows how filtration efficiency is affected by the flow rate of
aerosols
through the membrane.
[01351
FIG. 14 shows how the pressure drop across the menibrane, which is a
measure of
breathability of the membrane, is affected by the flow rate of aerosols
through the membrane.
101361
FIG. 15 shows an embodiment of a system for removing volatile organic
compounds and carbon dioxide that is composed of a photocatalyst-impregnated
nanofibrous
polymer membrane and a carbon nanofiber membrane.
[01371
FIG. 16 shows the basic repeat unitS of rectangular, hexagonal, and
trihexagonal
opening patterns for mesh substrates.
101381
FIG. 17 shows a schematic representation of a flexible, breathable,
and.
antimicrobial facemask based on an all-nanofiber TENG (NF-TENG) platform.
(0139)
The previous description of the disclosed embodiments is provided to
enable any
person skilled in the art to make or use the invention, disclosed herein,
Although the various
inventive aspects arc = disclosed in the context of one or more illustrated
embodiments,
implementations, and examples, it should be understood by those skilled in the
art that the
invention extends beyond the specifically disclosed embodiments to other
alternative
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PCT/US2022/077443
embodiments and/or uses of the invention and obvious modifications and
equivalents thereof
It should bealso understood that the scope of this disclosure includes the
various combinati ons
or .sub-combinations of the specific 'features and aspeetsof the embodiments
diselOsed herein,
Such that the various features, .modes of implementatiOn, and aspects of the
disclosed subject
matter.intly be combined with or sub.i.4itoled 'for one another. The generic
principles defined
herein may be applied to other embodiments-without departing from the spirit
or scope of the
disclosure. Thus, the present.diselosure is not intended to be limited to the
embodiments shown
herein but is to be accorded the widest scope- consistent with the principles
and novel features
disclosed herein.
MI 0] All references cited are hereby expressly incorporated
herein by reference.
26
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