Ionic liquid-based coatings and methods for producing articles coated therewith - Patent Application 20070122997

Abstract

To provide: a surface coating, and particularly an ionic liquid-based coating for forming antimicrobial and self-disinfecting surfaces on both porous and nonporous articles; and a method of making articles coated with the coating.SOLUTION: An ionic liquid-based coating comprises: at least one ionic liquid; an adhesive; and at least one additive selected from the group consisting of a disinfectant, a viscosity modifier, a pH buffer, a fragrance, and combinations thereof. When the ionic liquid-based coating is applied to form a coated substrate, the coated substrate has disinfecting and / or antimicrobial properties. When the ionic liquid-based coating is applied to a porous substrate to form a coated porous substrate, the coated porous substrate has increased filtration efficiency for airborne and / or waterborne particulate matter without increasing flow resistance.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 920,764, filed May 15, 2019.

[0002] The disclosure of this patent application relates to surface coatings, and in particular to ionic liquid-based coatings for forming antimicrobial and self-sanitizing surfaces on both porous and non-porous articles, and for improving the filtration properties of porous filter media. [Background technology]

[0003] Most ionic liquids possess inherent antibacterial properties due to their low vapor pressure, resulting in negligible radiation, making them ideal materials for environmental applications. Furthermore, their favorable solvent properties allow them to absorb and dissolve other disinfectants or air pollutants, thereby enhancing their inherent disinfecting and purifying capabilities. Furthermore, the high chemical and thermal stability of ionic liquids ensures the absence of unwanted decomposition by-products. However, utilizing these desirable properties for surface coatings has been difficult because ionic liquids generally have very high viscosity and poor surface wetting capabilities, making it difficult to prepare uniform and stable ionic liquid-based coatings on porous or non-porous substrates. Therefore, there is a need for a method for producing ionic liquid-based coatings and articles coated therewith that can solve the above problems. Summary of the Invention

[0004] Ionic liquid-based coatings are coatings for both porous and non-porous materials. As a non-limiting example, porous substrates coated with ionic liquid-based coatings may be used to disinfect and remove microorganisms from air and water, provide antimicrobial surfaces to prevent microbial contamination, or improve the filtration efficiency of porous materials against airborne or waterborne particulate matter without increasing flow resistance. As a further non-limiting example, non-porous substrates coated with ionic liquid-based coatings may be used to form surfaces that are self-disinfecting of microorganisms that come into contact with the surface. Ionic liquid-based coatings comprise at least one ionic liquid, an adhesive, at least one additive that may be a disinfectant, a viscosity modifier, a pH buffer, a fragrance, and combinations thereof. When applied to a substrate to form a coated substrate, the coated substrate has disinfecting and / or antimicrobial properties, and when applied to a porous substrate to form a coated porous substrate, the coated porous substrate has improved filtration efficiency against airborne and / or waterborne particulate matter without increasing flow resistance.

[0005] Non-limiting examples of adhesives include sols or dispersions of metal oxides, zeolites, carbonaceous particles, or combinations thereof. As further non-limiting examples, the adhesive may be a silica sol prepared from a water-soluble silica source and silicon alkoxide, colloidal alumina, silica and red-brown sol, activated carbon sol, zeolite sol, or a zeolite-metal oxide mixed sol. Typical water-soluble silica sources include silicic acid solutions, and typical silica alkoxides may include, but are not limited to, tetramethyl orthosilicate, tetraethyl orthosilicate, and tetrapropyl orthosilicate. The sols or dispersions have different pH values, which can create interactions between the at least one ionic liquid and the adhesive to achieve uniform and stable adsorption of the at least one ionic liquid on the adhesive interlayer.

[0006] Non-limiting examples of the at least one ionic liquid include cations selected from imidazolium, pyridinium, ammonium, phosphonium, and combinations thereof. Further non-limiting examples of the at least one ionic liquid include anions selected from chloride, bromide, iodide, nitrate, hydrogen sulfate, acetate, tetrafluoroborate, hexafluorophosphate, thiocyanate, trifluoromethanesulfonate, bis(trifluoromethylsulfonyl)imide, and combinations thereof.

[0007] Non-limiting examples of disinfecting additives include antimicrobial metal salts, antimicrobial metal particles, phytochemicals, essential oils, acid disinfectants, and combinations thereof. Non-limiting examples of viscosity adjusting additives include water, methanol, ethanol, isopropanol, acetonitrile, tetrahydrofuran, and combinations thereof. Non-limiting examples of pH buffers include acetic acid, sodium acetate, citric acid, sodium citrate, potassium dihydrogen phosphate, and combinations thereof. Non-limiting examples of fragrance or perfume additives include aliphatic hydrocarbons, aldehydes, alcohols, esters, aromatic compounds, and combinations thereof.

[0008] To produce an article coated with an ionic liquid-based coating, an adhesive is applied to a substrate to form an adhesive interface layer. A composition is then applied to the adhesive interface layer, where the composition is formed from at least one ionic liquid, at least one additive, which may be a disinfectant as described above, a viscosity modifier, a pH buffer, a fragrance, or a combination thereof. As described above, the substrate may be either a porous substrate or a non-porous substrate. Non-limiting examples of application techniques for applying the adhesive to the substrate include at least one of wiping, brushing, dip-coating, spin-coating, and spraying the adhesive onto the substrate. After applying the adhesive to the substrate, the adhesive may be dried. Non-limiting examples of application techniques for applying the composition to the adhesive interface layer include at least one of wiping, brushing, dip-coating, spin-coating, and spraying the composition onto the adhesive interface layer. After applying the composition to the adhesive interface layer, the composition may be dried.

[0009] Alternatively, to produce an article coated with an ionic liquid-based coating, an alternative composition is applied to a substrate. The composition includes at least one ionic liquid, at least one additive, which may be a disinfectant as described above, a viscosity modifier, a pH buffer, a fragrance, or a combination thereof. As described above, the substrate may be either a porous or non-porous substrate. In this embodiment, the at least one ionic liquid is incorporated into an adhesive to form a composition. Non-limiting examples of incorporation techniques for incorporating the at least one ionic liquid into the adhesive to form the composition include physical mixing, electrostatic adsorption, and chemical functionalization. Non-limiting examples of application techniques for applying the composition to the substrate include at least one of wiping, brushing, dip coating, spin coating, and spraying the adhesive onto the substrate. After applying the composition to the substrate, the composition may be dried. As described above, the sol or dispersion has a different pH value, which can create an interaction between the at least one ionic liquid and the adhesive to stabilize the composition without precipitation.

[0010] These and other features of the present subject matter will become readily apparent from further review of the specification that follows. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 shows a schematic of a method for producing an article coated with an ionic liquid-based coating.

[0012] [Figure 2] FIG. 2 shows a schematic of an alternative method for producing an article coated with an ionic liquid-based coating.

[0013] [Figure 3A] FIG. 3A is a scanning electron microscope (SEM) image of a cellulose paper sample.

[0014] [Figure 3B]FIG. 3B is an SEM image of the cellulose paper with the adhesive interlayer formed thereon, shown at a magnification of X200.

[0015] [Figure 3C] FIG. 3C is an SEM image of the cellulose paper with the adhesive interlayer formed thereon, shown at a magnification of X2500.

[0016] [Figure 3D] Figure 3D shows an SEM image of cellulose paper with an ionic liquid-based coating.

[0017] [Figure 4A] FIG. 4A is an SEM image of a high efficiency particulate air (HEPA) filter surface.

[0018] [Figure 4B] FIG. 4B is an SEM image of the HEPA filter surface with the adhesive interlayer formed thereon.

[0019] [Figure 4C] FIG. 4C is an SEM image of the HEPA filter surface on which the ionic liquid-based coating was formed.

[0020] [Figure 5] Figure 5 is a graph comparing the Fourier transform infrared (FTIR) spectra of a HEPA filter, a pure ionic liquid sample (IL), a HEPA filter with a metal oxide interlayer (HEPA / MO), and a HEPA filter with an ionic liquid-based coating (HEPA / MO / IL).

[0021] [Figure 6A] FIG. 6A is a photograph showing the inhibition zone of deionized distilled water (DDI) for E. coli samples.

[0022] [Figure 6B] FIG. 6B is a photograph showing the inhibition zone of ethanol for E. coli samples.

[0023] [Figure 6C] FIG. 6C is a photograph showing the inhibition zone of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4) ionic liquid for E. coli samples.

[0024] [Figure 6D] FIG. 6D is a photograph showing the zone of rejection of HEPA filter samples with EMIM-BF4 ionic liquid coatings for E. coli samples.

[0025] [Figure 6E] FIG. 6E is a photograph showing the zone of rejection of a HEPA filter sample with a 1-butyl-3-methylimidazolium iodide (BMIM-I) ionic liquid coating for an E. coli sample.

[0026] [Figure 7A] FIG. 7A is a graph comparing the antibacterial activity against E. coli as a function of ionic liquid loading of HEPA filters with EMIM-BF4, 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4), 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIM-BF4), 1-decyl-3-methylimidazolium tetrafluoroborate (DMIM-BF4), 1-ethyl-3-methylimidazolium tetrafluorophosphate (EMIM-PF6), and 1-butyl-3-methylimidazolium tetrafluorophosphate (BMIM-PF6) ionic liquid coatings.

[0027] [Figure 7B] FIG. 7B is a graph comparing the antibacterial activity against S. aureus as a function of ionic liquid loading of HEPA filters with EMIM-BF4, BMIM-BF4, HMIM-BF4, and DMIM-BF4 ionic liquid coatings.

[0028] [Figure 8A]FIG. 8A is a bar graph comparing the minimum ionic liquid loading for 99.99% reduction of 10 CFU / ml of E. coli on HEPA filters with EMIM-BF, BMIM-BF, HMIM-BF, DMIM-BF, BMIM-I, 1-butyl-3-methylimidazolium tetrafluoroacetate (BMIM-Ac), and Bronsted acidic ionic liquid (1-butyl-3-methylimidazolium hydrogen sulfate, BMIM-HSO) ionic liquid coatings.

[0029] [Figure 8B] FIG. 8B is a bar graph comparing the minimum ionic liquid loading for 99.999% reduction of 10 5 CFU / ml of S. aureus on HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO 4 ionic liquid coatings.

[0030] [Figure 9A] FIG. 9A is a graph comparing the antibacterial activity against methicillin-resistant S. aureus as a function of ionic liquid loading of HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO 4 ionic liquid coatings.

[0031] [Figure 9B] FIG. 9B is a graph comparing the antibacterial activity against S. pneumoniae as a function of ionic liquid loading of HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO 4 ionic liquid coatings.

[0032] [Figure 9C] FIG. 9C is a graph comparing the antibacterial activity against L. pneumophilia as a function of ionic liquid loading of HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO 4 ionic liquid coatings.

[0033] [Figure 9D]FIG. 9D is a graph comparing the antibacterial activity against S. marcescens as a function of ionic liquid loading of HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO 4 ionic liquid coatings.

[0034] [Figure 10] FIG. 10 is a graph comparing the antibacterial activity against H1N1 influenza virus as a function of ionic liquid loading of HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO 4 ionic liquid coatings.

[0035] [Figure 11] Figure 11 is a graph comparing the antibacterial activity against E. coli as a function of ionic liquid loading of HEPA filters with BMIM-PF6, EMIM-BF4, and BMIM-PF6·EMIM-BF4 mixed ionic liquid coatings.

[0036] [Figure 12] FIG. 12 is a bar graph comparing the antibacterial activity against 10 CFU / ml of S. aureus for a 10 minute contact time of BMIM-BF4, BMIM-BF4 and 1 wt% Cu, BMIM-BF4 and 5 wt% Cu, BMIM-BF4 and 1 wt% thymol, and BMIM-BF4 and 1 wt% thymol coatings.

[0037] [Figure 13] FIG. 13 is a plot comparing microbial counts of a commercial HEPA filter and a HEPA filter with an ionic liquid-based coating in a three-week field trial.

[0038] [Figure 14] FIG. 14 is a graph comparing the particulate matter filtration efficiency of pristine uncoated H11 and H13 HEPA filters and H11 and H13 HEPA filters with ionic liquid-based coatings.

[0039] [Figure 15] FIG. 15 is a graph comparing the particulate matter filtration efficiency of an initial uncoated H13 HEPA filter and H13 HEPA filters with a range of BMIM-I coating loads.

[0040] [Figure 16] FIG. 16 is a graph comparing the particulate matter filtration efficiency of H13 HEPA filters with EMIM-BF4, BMIM-BF4, HMIM-BF4, and DMIM-BF4 ionic liquid coatings.

[0041] [Figure 17] FIG. 17 is a graph comparing the particulate matter filtration efficiency of an initial uncoated H13 HEPA filter using TiO sol, NaA zeolite sol, and activated carbon (AC) as an adhesive and an H13 HEPA filter with an ionic liquid coating.

[0042] [Figure 18] FIG. 18 is a graph comparing the particulate matter filtration efficiency of a pristine uncoated H13 HEPA filter, a hydrothermally treated H13 HEPA filter, an H13 HEPA filter with an ionic liquid-based coating, and an H13 HEPA filter with a hydrothermally treated ionic liquid-based coating.

[0043] [Figure 19] FIG. 19 is a graph comparing the inhibition rates of bleach (1:99), ethanol, glycerol, and the ionic liquids BMIM-I, BMIM-BF4, and EMIM-BF4 on A549 lung epithelial cells.

[0044] Like reference characters indicate corresponding features throughout the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION

[0045] Ionic liquid-based coatings are coatings for both porous and non-porous materials. As a non-limiting example, porous substrates coated with ionic liquid-based coatings may be used to disinfect and remove microorganisms from air and water, provide antimicrobial surfaces to prevent microbial contamination, or improve the filtration efficiency of porous materials against airborne or waterborne particulate matter without increasing flow resistance. As a further non-limiting example, non-porous substrates coated with ionic liquid-based coatings may be used to form surfaces capable of self-sanitizing microorganisms that come into contact with the surface. Ionic liquid-based coatings comprise at least one ionic liquid, an adhesive, at least one additive that may be a disinfectant, a viscosity modifier, a pH buffer, a fragrance, and combinations thereof. Non-limiting examples of porous articles and substrates to which ionic liquid-based coatings may be applied include ceramic membranes, cellulose paper, and high-efficiency particulate air (HEPA) filters. Non-limiting examples of non-porous substrates to which ionic liquid-based coatings may be applied include glass surfaces and polyvinyl chloride boards.

[0046] Non-limiting examples of adhesives include sols or dispersions of metal oxides, zeolites, carbonaceous particles, or combinations thereof. As further non-limiting examples, the adhesive may be a silica sol prepared from a water-soluble silica source and silicon alkoxide, colloidal alumina, silica and red-brown sol, activated carbon sol, zeolite sol, or a zeolite-metal oxide mixed sol. Typical water-soluble silica sources include silicic acid solutions, and typical silica alkoxides may include, but are not limited to, tetramethyl orthosilicate, tetraethyl orthosilicate, and tetrapropyl orthosilicate. The sols or dispersions have different pH values, which can tailor the interaction between the at least one ionic liquid and the adhesive to achieve uniform and stable adsorption of the at least one ionic liquid on the adhesive interlayer.

[0047] Non-limiting examples of the at least one ionic liquid include cations selected from imidazolium, pyridinium, ammonium, phosphonium, and combinations thereof. Further non-limiting examples of the at least one ionic liquid include anions selected from chloride, bromide, iodide, nitrate, hydrogen sulfate, acetate, tetrafluoroborate, hexafluorophosphate, thiocyanate, trifluoromethanesulfonate, bis(trifluoromethylsulfonyl)imide, and combinations thereof.

[0048] Non-limiting examples of disinfecting additives include antimicrobial metal salts, antimicrobial metal particles, phytochemicals, essential oils, acid disinfectants, and combinations thereof. Non-limiting examples of viscosity adjusting additives include water, methanol, ethanol, isopropanol, acetonitrile, tetrahydrofuran, and combinations thereof. Non-limiting examples of pH buffers include acetic acid, sodium acetate, citric acid, sodium citrate, potassium dihydrogen phosphate, and combinations thereof. Non-limiting examples of fragrance or perfume additives include aliphatic hydrocarbons, aldehydes, alcohols, esters, aromatic compounds, and combinations thereof.

[0049] As shown schematically in FIG. 1 , to produce an article coated with an ionic liquid-based coating, an adhesive is applied to a substrate to form an adhesive interface layer. A composition is then applied to the adhesive interface layer, where the composition is formed from at least one ionic liquid, at least one additive, which may be a disinfectant as described above, a viscosity modifier, a pH buffer, a fragrance, or a combination thereof. As described above, the substrate may be either a porous substrate or a non-porous substrate. Non-limiting examples of application techniques for applying the adhesive to the substrate include at least one of wiping, brushing, dip-coating, spin-coating, and spraying the adhesive onto the substrate. After applying the adhesive to the substrate, the adhesive may be dried. Non-limiting examples of application techniques for applying the composition to the adhesive interface layer include at least one of wiping, brushing, dip-coating, spin-coating, and spraying the composition onto the adhesive interface layer. After applying the composition to the adhesive interface layer, the composition may be dried.

[0050] Alternatively, to produce an article coated with an ionic liquid-based coating, an alternative composition is applied to a substrate. The composition includes at least one ionic liquid, at least one additive, which may be a disinfectant as described above, a viscosity modifier, a pH buffer, a fragrance, or a combination thereof. As described above, the substrate may be either a porous or non-porous substrate. In this embodiment, the at least one ionic liquid is incorporated into an adhesive to form a composition. Non-limiting examples of incorporation techniques for incorporating the at least one ionic liquid into the adhesive to form the composition include physical mixing, electrostatic adsorption, and chemical functionalization. Non-limiting examples of application techniques for applying the composition to the substrate include at least one of wiping, brushing, dip coating, spin coating, and spraying the adhesive onto the substrate. After applying the composition to the substrate, the composition may be dried. As described above, the sol or dispersion has a different pH value, which can tailor the interaction between the at least one ionic liquid and the adhesive to stabilize the composition without precipitation.

[0051] Figure 3A is a scanning electron microscope (SEM) image of a cellulose paper sample. Figure 3B is an SEM image of the cellulose paper with an adhesive interlayer formed thereon, shown at a magnification of 200x. Figure 3C is an SEM image of the cellulose paper with an adhesive interlayer formed thereon, shown at a magnification of 2500x. Figure 3D is an SEM image of the cellulose paper with an ionic liquid-based coating formed thereon. As shown in Figure 3A, the cellulose paper exhibits an interconnected porous structure made up of cellulose fibers. After applying the metal oxide sol to the cellulose paper, the cellulose fibers are covered with a uniform metal oxide interlayer (shown in Figures 3B and 3C). The metal oxide interlayer aids in the dispersion and adsorption of the ionic liquid onto the cellulose fibers, forming a uniform and stable ionic liquid coating. As shown in Figures 3B-3D, the metal oxide interlayer and ionic liquid coating do not change the interconnected porous structure of the cellulose paper.

[0052] Figure 4A is an SEM image of a high-efficiency particulate air (HEPA) filter surface. Figure 4B is an SEM image of a HEPA filter surface with an adhesive interlayer formed thereon. Figure 4C is an SEM image of a HEPA filter surface with an ionic liquid-based coating formed thereon. Compared to the initial HEPA filter shown in Figure 4A, the polypropylene fibers in the functional layer of the HEPA filter are coated with a thin adhesive interlayer (shown in Figure 4B). After further coating with ionic liquid and drying, the ionic liquid is fixed onto the adhesive interlayer, forming a uniform ionic liquid-based coating (shown in Figure 4B).

[0053] Ionic liquids have poor surface wetting properties for HEPA filters. By adjusting viscosity, surface wetting, and adhesion using additives and adhesives, ionic liquid-based coatings can be formed on HEPA filters. Using Fourier transform infrared spectroscopy (FTIR), Figure 5 compares the FTIR spectra of a pristine HEPA filter, a pure ionic liquid sample (IL), a HEPA filter with a metal oxide interlayer (HEPA / MO), and a HEPA filter with an ionic liquid-based coating (HEPA / MO / IL). Figure 5 shows the 1030 cm peak, which corresponds to the asymmetric vibration of the anion of the ionic liquid. -1 Based on the bands in Fig. 1, it is clear that the ionic liquid was successfully formed on the HEPA filter. By adjusting the adhesive interlayer and ionic liquid, the texture and ionic liquid loading can be easily manipulated to balance flow resistance, antibacterial activity, and filtration efficiency. By optimizing the ratio of adhesive sol to ionic liquid and the surface loading of the sol particles, a homogeneous composition of adhesive and ionic liquid can be formed, enabling the one-step preparation of the above ionic liquid-based coatings.

[0054] Figure 6A is a photograph showing the zone of inhibition of deionized distilled water (DDI) for E. coli samples. Figure 6B is a photograph showing the zone of inhibition of ethanol for E. coli samples. Figure 6C is a photograph showing the zone of inhibition of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4) ionic liquid for E. coli samples. Figure 6D is a photograph showing the zone of inhibition of a HEPA filter sample with an EMIM-BF4 ionic liquid coating for E. coli samples. Figure 6E is a photograph showing the zone of inhibition of a HEPA filter sample with a 1-butyl-3-methylimidazolium iodide (BMIM-I) ionic liquid coating for E. coli samples. As shown in Figures 6A and 6B, there is no clear zone of inhibition due to the promicrobial properties of DDI and the evaporation of ethanol. In Figure 6C, pure ionic liquid (EMIM-BF4) shows a clear zone of inhibition for E. coli in agar medium. 6D and 6E, a larger zone of inhibition appears with increasing ionic liquid loading. The HEPA filter with the BMIM-I coating in FIG. 6E has a stronger inhibition ability against E. coli compared to the HEPA filter with the EMIM-BF4 coating, which is similar to the HEPA filter with the bleach coating.

[0055] Figure 7A is a graph comparing the antibacterial activity against E. coli as a function of ionic liquid loading for HEPA filters with EMIM-BF4, 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4), 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIM-BF4), 1-decyl-3-methylimidazolium tetrafluoroborate (DMIM-BF4), 1-ethyl-3-methylimidazolium tetrafluorophosphate (EMIM-PF6), and 1-butyl-3-methylimidazolium tetrafluorophosphate (BMIM-PF6) ionic liquid coatings. Figure 7B is a graph comparing the antibacterial activity against S. aureus as a function of ionic liquid loading for HEPA filters with EMIM-BF4, BMIM-BF4, HMIM-BF4, and DMIM-BF4 ionic liquid coatings. As shown, ionic liquids with longer alkyl chains exhibit better antibacterial activity, which is due to the hydrophobic properties of the longer alkyl chains. Figure 8A shows the antibacterial activity of 10% EMIM-BF4, BMIM-BF4, HMIM-BF4, DMIM-BF4, BMIM-I, 1-butyl-3-methylimidazolium tetrafluoroacetate (BMIM-Ac), and Brønsted acidic ionic liquid (1-butyl-3-methylimidazolium hydrogen sulfate, BMIM-HSO4) ionic liquid coatings on HEPA filters. 4 1 is a bar graph comparing the minimum ionic liquid loading for a 99.99% reduction of E. coli CFU / ml. - , HSO4 - , CH3COO - The anion of BF4 - Figure 8B shows the antibacterial activity against E. coli at 10% on HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO ionic liquid coatings (i.e., lower minimum ionic liquid loading on HEPA filters). 5 1 is a bar graph comparing the minimum ionic liquid loading for a 99.99% reduction of S. aureus in CFU / ml.

[0056] Figure 9A is a graph comparing the antibacterial activity of HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO4 ionic liquid coatings against methicillin-resistant S. aureus as a function of ionic liquid load. Figure 9B is a graph comparing the antibacterial activity of HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO4 ionic liquid coatings against S. pneumoniae as a function of ionic liquid load. Figure 9C is a graph comparing the antibacterial activity of HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO4 ionic liquid coatings against L. pneumophilia as a function of ionic liquid load. Figure 9D is a graph comparing the antibacterial activity of HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO4 ionic liquid coatings against S. marcescens as a function of ionic liquid load. Figures 9A-9D demonstrate that the coatings exhibit good antibacterial activity against a variety of different microorganisms.

[0057] FIG. 10 is a graph comparing the antibacterial activity against H1N1 influenza virus as a function of ionic liquid loading for HEPA filters with BMIM-I, BMIM-Ac, and BMIM-HSO ionic liquid coatings. As shown, the ionic liquid-based coatings exhibited the highest antibacterial activity against H1N1 influenza virus as a function of ionic liquid loading at 30 g / m 2 The HEPA filter with BMIM-I coating can completely inactivate viruses when the ionic liquid loading reaches 3.5 g / m. 2 Even at concentrations as low as 1000 ppm, it can reduce 99.97% of the H1N1 influenza virus. These results confirm that HEPA filters with ionic liquid-based coatings have broad-spectrum antibacterial activity.

[0058] Figure 11 shows the ionic liquid loading of HEPA filters with BMIM-PF6, EMIM-BF4, and BMIM-PF6·EMIM-BF4 mixed ionic liquid coatings at 10 41 is a graph comparing the antibacterial activity against E. coli in CFU / ml. As shown, the HEPA filter with a mixed coating of BMIM-PF6 and EMIM-BF4 exhibits significantly higher antibacterial activity than the HEPA filters with only BMIM-PF6 and only EMIM-BF4. FIG. 12 shows the synergistic effect of ionic liquid and additives on the antibacterial activity of HEPA filters with BMIM-BF4 ionic liquid-based coating. The addition of other disinfectants, such as metal ions and essential oils, can greatly improve the antibacterial activity of HEPA filters with ionic liquid-based coatings. The HEPA filter with BMIM-BF4 coating could only reduce S. aureus by 70% after 10 minutes of contact time. A small amount of Cu 2+ and thymol were added to the ionic liquid coating, and then the mixed coating (1 wt% Cu 2+ , 1 wt% thymol, and 5 wt% thymol) were able to reduce 99.999% of S. aureus after a 10-minute contact time.

[0059] A commercial HEPA filter and a HEPA filter with an ionic liquid-based coating were assembled into an air purifier and a three-week field test was conducted in a regular university classroom and a wet lab. Figure 13 compares the results of the field test. After one week, the number of microorganisms accumulated on the HEPA filter with the ionic liquid-based coating was 9% of that on the commercial HEPA filter. Even after two weeks, under conditions with a higher number of people (63 people / day vs. 19 people / day), the number of microorganisms accumulated on the HEPA filter with the ionic liquid-based coating was still lower than that on the commercial HEPA filter.

[0060] Figure 14 is a graph comparing the filtration efficiency of particulate matter (i.e., sodium chloride aerosol) between the initial uncoated H11 and H13 HEPA filters and the H11 and H13 HEPA filters with the BMIM-I coating. Generally, both the H11 and H13 HEPA filters with the BMIM-I coating exhibit improved filtration efficiency across the entire particle size distribution range (<0.3 μm, 0.3 μm to 1.0 μm, 1.0 μm to 2.5 μm, 2.5 μm to 10 μm, and 0.02 to 1.0 μm) without an increase in flow resistance (0.2 kPa pressure drop at 2 m / s airflow velocity). It can be seen that the H11 HEPA filter with the BMIM-I coating has a higher filtration efficiency than the H13 HEPA filter, indicating that the ionic liquid-based coating effectively upgrades the HEPA filter's rating. It is believed that the ionic liquid's loading, high viscosity, and good sorption capacity contribute to the improved filtration efficiency.

[0061] Figure 15 compares the particulate matter filtration efficiency of the original H13 HEPA filter and H13 HEPA filters with different loadings of ionic liquid-based coating. 2As the alkyl chain length increases, the filtration efficiency of the corresponding HEPA filter across the entire particle size distribution range gradually increases. Figure 16 compares the particulate filtration efficiency of H13 HEPA filters with different ionic liquid-based coatings. The H13 HEPA filter with the DMIM-BF4 coating, in which the ionic liquid has the longest alkyl chain, exhibits the highest filtration efficiency, while BMIM-BF4 (with a medium alkyl chain length) produces the lowest filtration efficiency. As the alkyl chain length increases, the ionic liquid exhibits higher viscosity, accompanied by lower hydrophilicity. Viscosity governs filtration efficiency, with higher viscosity promoting greater filtration efficiency. For aqueous sodium chloride aerosols, higher hydrophilicity also improves filtration efficiency. Figure 17 compares the particulate filtration efficiency of pristine H13 HEPA filters and H13 HEPA filters with ionic liquid-based coatings prepared using different adhesives. The H13 HEPA filter with ionic liquid-based coating using TiO2 sol as adhesive exhibits the highest filtration efficiency, while those using NaA zeolite sol and activated carbon sol as adhesive exhibit similar filtration efficiency.

[0062] An aging test was designed to study the stability of the ionic liquid-based coating by performing hydrothermal treatment of air filters under harsh conditions (90°C, 85% humidity) in a humidity chamber for 48 hours. As shown in Figure 18, the filtration efficiency of the H13 HEPA filter after hydrothermal treatment decreased to 89% of its initial value, while the filtration efficiency of the H13 HEPA filter with the ionic liquid-based coating after hydrothermal treatment remained above 98% of its initial value. This result indicates that the ionic liquid-based coating is more stable than the HEPA filter, and therefore, the HEPA filter with the ionic liquid-based coating has a longer lifespan compared to the initial uncoated HEPA filter.

[0063] Ionic liquids have been proven to be environmentally friendly and safe solvents. Because ionic liquid-based coatings show potential applications in air disinfection and purification, the cytotoxicity of the ionic liquids to A549 lung epithelial cells was evaluated and shown in Figure 19. EMIM-BF4 has the least cytotoxicity among the three ionic liquids. These ionic liquids, which lie between glycerol as a non-toxic cryoprotectant and ethanol as a common solvent, have very low cytotoxicity even at concentrations reaching 1.0 wt% in cell culture media. Their cytotoxicity is significantly lower than that of bleach (1:99), a common disinfectant. The vapor pressure of most ionic liquids is 10 at room temperature. -10 Because the pressure is on the order of Pa, it is highly unlikely that ionic liquid-based coatings will be released into the air, making them highly safe for large-scale applications.

[0064] Example 1: Silica sol (water-soluble silica raw material) Sodium silicate solution (2.9 g) was diluted to 40 ml with DDI water, and then diluted nitric acid (1 mol / l, 15.6 ml) was added under vigorous stirring to obtain an acidic silica sol with a pH value of 1.

[0065] Example 2: Silica sol (water-soluble silica raw material) Sodium silicate solution (2.9 g) was diluted to 40 ml with DDI water, and then diluted nitric acid (1 mol / l, 8.2 ml) was added under vigorous stirring to obtain an acidic silica sol with a pH value of 4.

[0066] Example 3: Silica sol (silicon alkoxide) Dilute nitric acid (0.14 mol / l, 9.6 ml) was added to tetraethyl orthosilicate (30 ml) under stirring, and then heated at 50° C. for 3 hours to obtain a transparent silica sol.

[0067] Example 4: Colloidal silica sol Commercially available colloidal silica sol (Ludox AS-40) was diluted with water to form colloidal silica sols with concentrations ranging from 5 to 20 wt %.

[0068] Example 5: Colloidal Alumina Sol Commercially available pseudoboehmite powder (3.4 g) was dispersed in DDI water (47 ml) under vigorous stirring, and then heated at 80°C. Dilute nitric acid (1.6 mol / L, 1.8 ml) was added. The resulting mixture was further stirred at 80°C for 6 hours to obtain a transparent alumina sol (1 mol / L).

[0069] Example 6: Colloidal titania sol Tetraisopropyl orthotitanate (10 ml) was dissolved in isopropanol (23.6 ml), and then HNO3 (2 mol / l, 3.4 ml) and DDI water (31.4 ml) were added under vigorous stirring to obtain an opaque suspension. The suspension was further stirred at 80 °C to evaporate the isopropanol and peptize the titania precipitate. The suspension was then cooled to room temperature and stirred overnight to obtain a transparent titania sol (1 mol / l).

[0070] Example 7: Silica-alumina sol Tetraethyl orthosilicate (22 ml) was added to the acidic boehmite sol (0.2 mol / l, 50 ml) under vigorous stirring, followed by stirring at room temperature for 24 h to form a transparent silica-alumina sol with a Si / Al ratio of 10.

[0071] Example 8: Silica-titania sol Tetraethyl orthosilicate (22 ml) was added to titania sol (1 mol / l, 50 ml) under vigorous stirring, followed by stirring at room temperature for 24 h to form a transparent silica-titania sol with a Si / Ti ratio of 2.

[0072] Example 9: Carbonaceous sol Carbonaceous particles were prepared by oxidizing activated carbon or graphite flakes with concentrated H2SO4, which was then dispersed in DDI water to form a carbonaceous sol. In a typical synthesis, graphite flakes (1 g) were slowly added to concentrated H2SO4 at 250 °C for 18 hours. The suspension was cooled to room temperature, washed with DDI water, filtered, and dispersed in DDI water.

[0073] Example 10: Graphene oxide sol Graphene nanosheets prepared from flake graphite by the modified Hummers method were dispersed in DDI water to form graphene oxide sols with concentrations ranging from 1 to 10 mg / ml.

[0074] Example 11: Zeolite sol Zeolite sols were prepared by treating commercially available zeolites with acid or base. NaA zeolite (1.5 g) was treated with HCl solution (5 mol / L, 8.5 g) for 30 minutes to obtain NaA zeolite sol. In another typical synthesis, HBeta zeolite (Si / Al = 37.5, 1 g) was treated with NaOH solution (5 mol / L, 19 g) for 30 minutes to obtain HBeta zeolite sol.

[0075] Example 12: Zeolite-metal oxide sol The zeolite sol prepared by the method of Example 11 and the metal oxide sol prepared by the methods of Examples 1 to 8 were mixed under stirring to form a zeolite-metal oxide sol.

[0076] Example 13: Ionic Liquid Solution (Water as Viscosity Modifier) DDI water may be used as a viscosity modifier to reduce the viscosity of ionic liquids for coating preparation. EMIM-BF4 was dissolved in DDI water to form ionic liquid solutions with concentrations ranging from 0.1 to 2.0 wt%. BMIM-BF4 was dissolved in DDI water to form ionic liquid solutions with concentrations ranging from 0.1 to 2.0 wt%. 1-Butyl-3-methylimidazolium hydrogen sulfate (BMIM-HSO4) was dissolved in DDI water to form ionic liquid solutions with concentrations ranging from 0.1 to 2.0 wt%. EMIM-I was dissolved in DDI water to form ionic liquid solutions with concentrations ranging from 0.1 to 2.5 wt%. 1-Butyl-3-methylimidazolium trifluoromethanesulfonate (BMIM-TFMS) was dissolved in DDI water to form ionic liquid solutions with concentrations ranging from 0.1 to 3.0 wt%.

[0077] Example 14: Ionic Liquid Solution (Alcohol as Viscosity Modifier) Alcohol may be used as a viscosity modifier to reduce the viscosity of the ionic liquid for coating preparation. In a typical synthesis, BMIM-I was dissolved in isopropanol to form an ionic liquid solution with a concentration ranging from 0.1 to 1 wt%.

[0078] Example 15: Ionic Liquid Solution (Acetonitrile as Viscosity Modifier) Acetonitrile may be used as a viscosity modifier to reduce the viscosity of the ionic liquid for coating preparation. In a typical synthesis, EMIM-BF4 was dissolved in acetonitrile to form an ionic liquid solution with a concentration ranging from 0.1 to 1 wt%.

[0079] Example 16: Ionic Liquid Solution (Tetrahydrofuran as Viscosity Modifier) Tetrahydrofuran may be used as a viscosity modifier to reduce the viscosity of the ionic liquid for coating preparation. In a typical synthesis, BMIM-PF6 was dissolved in tetrahydrofuran to form an ionic liquid solution with a concentration ranging from 0.1 to 0.5 wt%.

[0080] Example 17: Ionic Liquids and Metal Ions Metal ions may be used as another type of antiseptic agent to enhance the antimicrobial activity of ionic liquid coatings. The ionic liquid solutions described in Examples 13-15 were prepared using Cu 2+ , Zn 2+ , Ag + The final concentration of the metal ions ranged from 10 ppm to 2000 ppm.

[0081] Example 18: Ionic Liquids and Phytochemicals Phytochemicals, including essential oils and their active ingredients, may be used as another type of disinfectant to enhance the antimicrobial activity of ionic liquid coatings. The ionic liquid solutions described in Examples 14-16 were mixed with essential oils and their active ingredients, including thyme oil or thymol, tea tree oil or terpinen-4-ol, and cinnamon oil or cinnamaldehyde.

[0082] Example 19: Ionic liquid and fragrance Fragrances or perfumes may be added to ionic liquids to prepare pleasant-smelling ionic liquid coatings. The ionic liquid solutions described in Examples 14-16 were mixed with fragrance compounds including aliphatic hydrocarbons, aldehydes, alcohols, esters, and aromatic compounds.

[0083] Example 20: Ionic liquid and adhesive To prepare the ionic liquid coatings using the one-step process described above, the ionic liquid and adhesive may be mixed to form a homogeneous composition free of any precipitate. The ionic liquid solutions described in Examples 13-15 or the ionic liquid solutions described in Examples 17-19 were mixed with the adhesives described in Examples 1-8 to prepare ionic liquid and adhesive compositions.

[0084] Example 21: Adhesive Interlayer The adhesives described in Examples 1-8 may be applied to porous or non-porous substrates to form adhesive interlayers. In a typical preparation for a porous substrate, the adhesive was uniformly distributed onto the functionalized layer of a HEPA filter via a spray nozzle and then allowed to dry overnight at 40° C. In a typical preparation for a non-porous substrate, the adhesive was uniformly brushed onto a glass slide and then allowed to dry overnight at 40° C.

[0085] Example 22: Antibacterial coating (two-step process) Ionic liquids may be applied to porous or non-porous substrates with an adhesive interlayer to form ionic liquid-based antibacterial coatings. The ionic liquid solutions described in Examples 13-16 or the ionic liquid and additive compositions described in Examples 17-19 were uniformly distributed via a spray nozzle onto the adhesive interlayer of the porous or non-porous substrate, followed by drying at 40°C overnight.

[0086] Example 23: Antibacterial coating (one-step process) The ionic liquid and additive composition described in Example 20 may be applied directly to porous or non-porous substrates to form ionic liquid-based antimicrobial coatings. In a typical preparation for a porous substrate, the ionic liquid and additive composition was uniformly distributed onto the functionalized layer of a HEPA filter via a spray nozzle and then dried overnight at 40° C. In a typical preparation for a non-porous substrate, the ionic liquid and additive composition was uniformly brushed onto a glass slide and then dried overnight at 40° C.

[0087] Example 24: Inhibition Zone The bacterial suspension (0.1 ml) was spread onto a trypticase soy agar plate. Small pieces of HEPA filter with an ionic liquid coating were cut and then placed in the center of the plate where the bacteria were spread. The plate was incubated at room temperature for 48 hours.

[0088] Example 25: Antibacterial activity The bacterial suspension (0.1 ml) was evenly spread on the substrates with and without ionic liquid coating for 10 minutes. The substrates were then immersed in neutralizer (20 ml) in a culture tube for 30 minutes to stabilize any remaining bacteria and wash them off the surface. The neutralizer solution containing the collected bacteria was spread onto trypticase soy agar plates for growth culture. The plates were incubated at 37°C for 24 hours. The grown bacteria were counted based on the colony number formed.

[0089] The virus suspension (0.1 ml) was evenly spread on the substrate with or without ionic liquid coating for 10 minutes. The substrate was then immersed in the plate's neutralizing agent (6 ml) for 10 minutes. Next, all the liquid in the plate was removed and diluted to different concentrations, which were then added to a 96-well microplate containing MDCK cells grown in monolayer. The 96-well microplate was placed in a bacterial incubator at 37°C for 2 hours with 5% CO2. The supernatant was removed and further cultured for 48 hours. The virus concentration was measured using a 50% tissue culture infectious dose (TCID 50 ) was expressed as

[0090] Example 26: Field Testing Commercially available HEPA filters and ionic liquid-based coatings (1 g / m 2 TiO2 intermediate layer and 20g / m 2 HEPA filters with BMIM-I coating (of which BMIM-I is the most widely used coating) were collected in an air purifier for field testing. Three regular classrooms and a wet lab were selected for a three-week field test run. An infrared people counter was used to record the number of people, and microbial samples were collected from the commercial HEPA filters and the HEPA filters with the ionic liquid-based coating.

[0091] Example: Filtration efficiency The Sensdar ventilation fan reduces the airborne sodium chloride particles (approximately 10 5 particles / cm 3 The air was transferred from the production side to the filtration side through an air filter (effective area: 5 cm diameter). Air particle concentrations in different particle size distribution ranges were measured using a P-Trak 8525 particle counter and a particle counter sold by Shenzhen Korno Import & Export Co., respectively. Filtration efficiency was calculated based on the ratio of particle concentrations in the air on the filtration side to that on the production side. The flow velocity and pressure drop on the two sides were also recorded to compare the flow resistance of the original air filter and the air filter with the ionic liquid-based coating.

[0092] Example 28: Cytotoxicity test A549 lung epithelial cells were cultured in 25cm cultures with Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum, 100 U / ml streptomycin, and 50 U / ml penicillin at 37°C in a humidified atmosphere of 5% CO . 2Cells were grown in flasks. Subculture of confluent monolayers was performed using 0.05% trypsin and 0.53 mmol / L ethylenediaminetetraacetic acid in calcium- and magnesium-free Hanks' balanced salt solution (HBSS). Phase-contrast microscopy revealed prominent dome formation two days after confluence. For the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cells were grown at 2 × 10 5 Cells / well were placed in a 96-well microplate for 6 hours, after which the medium was gently changed to remove non-adherent cells. The plates were used for testing after 24 hours. After 4 hours of exposure to the ionic liquid diluted in DMEM, the medium was removed and the wells were gently washed with serum-free DMEM. 200 μl of MTT (1 mg / ml in HBSS) was added to each well and incubated for 4 hours. The medium was replaced with 100 μl of dimethyl sulfoxide for 20 minutes, and the absorbance at 595 nm was determined using a microplate reader. Each group consisted of 4 wells, and the experiment was performed in triplicate. The inhibition rate I was calculated as: where C is the absorbance of the control group containing cell solution and MTT, which shows the highest number of viable cells; S is the absorbance of the sample group containing cell solution, ionic liquid, and MTT, which shows the highest number of viable cells in the ionic liquid; and B is the absorbance of the blank group containing only pure culture medium and MTT, which is set to reduce interference from the natural environment.

[0093] It is understood that the methods for making ionic liquid-based coatings and articles coated therewith are not limited to the particular embodiments described above, but rather encompass any and all embodiments within the general language of the following claims that are enabled by the embodiments described herein, or that are shown in the drawings or described above in sufficient terms to enable one of ordinary skill in the art to make and use the claimed subject matter.

Claims

1. At least one ionic liquid selected from the group consisting of 1-hexyl-3-methylimidazolium tetrafluoroborate and 1-decyl-3-methylimidazolium tetrafluoroborate; a sol or dispersion adhesive selected from the group consisting of metal oxide adhesives, zeolite adhesives, carbonaceous particle based adhesives, and combinations thereof; at least one additive selected from the group consisting of a disinfectant, a viscosity modifier, a pH buffer, a fragrance, and combinations thereof; 1. An ionic liquid based coating comprising: when the ionic liquid-based coating is applied to a substrate to form a coated substrate, the coated substrate has disinfecting and / or antibacterial properties; When the ionic liquid-based coating is applied to a porous substrate to form a coated porous substrate, the coated porous substrate exhibits improved filtration efficiency for particulate matter in air and / or water without increasing flow resistance. Ionic liquid based coating.

2. 10. The ionic liquid-based coating of claim 1, wherein the adhesive is selected from the group consisting of a metal oxide adhesive, a zeolite adhesive, a carbonaceous particle-based adhesive, and combinations thereof.

3. the at least one additive comprises the disinfectant; 10. The ionic liquid-based coating of claim 1, wherein the disinfectant is selected from the group consisting of antimicrobial metal salts, antimicrobial metal particles, phytochemicals, essential oils, acid disinfectants, and combinations thereof.

4. the at least one additive comprises the viscosity modifier; 10. The ionic liquid based coating of claim 1, wherein the viscosity modifier is selected from the group consisting of water, methanol, ethanol, isopropanol, acetonitrile, tetrahydrofuran, and combinations thereof.

5. the at least one additive comprises the pH buffer; 10. The ionic liquid based coating of claim 1, wherein the pH buffer is selected from the group consisting of acetic acid, sodium acetate, citric acid, sodium citrate, potassium dihydrogen phosphate, and combinations thereof.

6. the at least one additive comprises the fragrance; 10. The ionic liquid-based coating of claim 1, wherein the fragrance is selected from the group consisting of aliphatic hydrocarbons, aldehydes, alcohols, esters, aromatic compounds, and combinations thereof.

7. applying a sol or dispersion adhesive selected from the group consisting of metal oxide adhesives, zeolite adhesives, carbonaceous particle based adhesives, and combinations thereof to a substrate to form an adhesive interlayer; applying a composition to the adhesive interface layer; Equipped with The composition comprises: at least one ionic liquid selected from the group consisting of 1-hexyl-3-methylimidazolium tetrafluoroborate and 1-decyl-3-methylimidazolium tetrafluoroborate; at least one additive selected from the group consisting of a disinfectant, a viscosity modifier, a pH buffer, a fragrance, and combinations thereof; Equipped with A method for producing an article coated with an ionic liquid-based coating.

8. 8. The method of claim 7, wherein applying the adhesive to the substrate to form the adhesive interface layer comprises applying the adhesive to a porous substrate.

9. 8. The method of claim 7, wherein applying the adhesive to the substrate to form the adhesive interface layer comprises applying the adhesive to a non-porous substrate.

10. 8. The method of claim 7, wherein applying the adhesive to the substrate to form the adhesive interface layer comprises at least one of wiping, brushing, dip coating, spin coating, and spraying the adhesive onto the substrate.

11. further comprising the step of drying the adhesive. A method for producing an article coated with the ionic liquid-based coating of claim 10.

12. 8. The method of claim 7, wherein applying the composition to the adhesive interface layer comprises at least one of wiping, brushing, dip coating, spin coating, and spraying the composition onto the adhesive interface layer.

13. further comprising the step of drying the adhesive. A method for producing an article coated with the ionic liquid-based coating of claim 12.

14. 8. The method of claim 7, wherein the adhesive is selected from the group consisting of a metal oxide adhesive, a zeolite adhesive, a carbonaceous particle based adhesive, and combinations thereof.

15. the at least one additive comprises the disinfectant; 8. The method of claim 7, wherein the disinfectant is selected from the group consisting of antimicrobial metal salts, antimicrobial metal particles, phytochemicals, essential oils, acid disinfectants, and combinations thereof.

16. applying a composition to a substrate; The composition comprises a sol or dispersion adhesive selected from the group consisting of metal oxide adhesives, zeolite adhesives, carbonaceous particle based adhesives, and combinations thereof; at least one ionic liquid selected from the group consisting of 1-hexyl-3-methylimidazolium tetrafluoroborate and 1-decyl-3-methylimidazolium tetrafluoroborate; at least one additive selected from the group consisting of a disinfectant, a viscosity modifier, a pH buffer, a fragrance, and combinations thereof; A method for producing an article coated with an ionic liquid-based coating.

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