Durable water- and oil-repellent polymeric device

Abstract

A durable superomniphobic device is proposed, where the polymeric device has a surface including dual-recessed microcolumns, the dual-recessed microcolumns being located within cavities that are separated within a matrix of interconnected dual-recessed walls. The dual-recessed matrix can be in a pattern where walls that are equal to or greater in height than the microcolumns intersect or otherwise contact to provide protection for the more fragile microcolumns. These durable superomniphobic devices can be formed by injection molding and can repel liquids having a surface tension of from about 18 to about 98 mN m-1 and exhibit a liquid contact angle of greater than or equal to 150°.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of U.S. Patent Application Serial No. 63 / 266,934, filed on January 19, 2022, which is incorporated herein by reference in its entirety, including any tables, drawings, or illustrations. Technical field

[0003] The present invention belongs to the field of polymer devices, and particularly relates to a durable polymer device that repels water and oil. Background art

[0004] Each year, approximately $20 billion worth of disposable plastics are consumed solely for biomedical and / or chemical testing, where these plastics are contaminated with potentially infectious pathogen residues and hazardous waste surfaces, and the pathogen residues and hazardous waste cost an additional $20 billion to treat for disposal. Additionally, $20 billion worth of disposable tableware is consumed each year and disposed of as plastic waste, exacerbating global plastic pollution. Cooking utensils are easily contaminated with cooking oil, which requires large amounts of water to clean them. If these devices could be replaced with reusable plastic devices that are non - sticky to liquids, significant cost savings would result. Therefore, durable water - and oil - repellent plastic devices that replace disposable plastic devices would reduce waste, conserve water, and ease cleaning work and water consumption.

[0005] Minimization of the liquid-solid contact area is the common mode leading to super-liquid repellency. Super-repellency refers to where the liquid has an apparent contact angle greater than 150° with the surface, where small beads that are approximately spherical roll off at an angle of less than 5°. For example, micro-columns are widely used to make surfaces superhydrophobic, where the liquid is supported by the micro-columns and only contacts the top surface of the micro-columns, thus greatly reducing the liquid-solid contact area, as shown in FIG. 1A. However, such micro-columns cannot suspend low surface tension oils and do not have oil repellency. To obtain both water repellency and oil repellency simultaneously, an all-round repellency, double-recessed structure is required, as they can provide additional support to suspend low surface tension oils in the Cassie state, as shown in FIG. 1B. Unfortunately, these micro-columns are fragile, as shown in FIG. 1C, and are easily damaged by mechanical wear, thus lacking robustness. By adding structures to include protective elements, such as larger micro-columns or forming interconnected microstructures as sacrificial layers for protecting the fine-scale columns from wear, the mechanical robustness of the surface has been solved. Unfortunately, these surfaces are easily contaminated by low surface tension oils because they lack recessed structures. Recently, more robust structures for superhydrophobic surfaces have been fabricated, where "protective armour" microstructures have been constructed, where the armour matrix is filled with superhydrophobic nanoparticles, as shown in FIG. 1D, where the microstructures are formed in a strongly ridged material with pockets such as inverted pyramids, and the pockets are filled with hydrophobic nanoparticles. This device as a composite material requires the fabrication of a silicon, metal, ceramic, or glass matrix that must be filled with superhydrophobic applied nanoparticles. These structures lack the characteristics that can make the surface resistant to oils and other fluids besides water-based fluids. Therefore, there is still a need for a device with a surface that is both superhydrophobic and superoleophobic (superomniphobic) and robust. In addition, a method for easily preparing a device with such a surface must be determined. SUMMARY OF THE INVENTION

[0006] One embodiment relates to a durable superomniphobic device that is a polymer having a surface that includes double-recessed micro-columns located within pockets that are separated within a matrix of interconnected double-recessed walls, i.e., armour. The polymer can be a thermoplastic resin or a thermosetting resin. The polymer can include additives such as catalysts, particulate fillers, or stabilizers. The double-recessed matrix can be periodic, quasi-periodic, aperiodic, or any combination thereof in pattern. The pattern can include multiple squares, rectangles, triangles, hexagons, intersecting circles, intersecting ellipses, or any irregular shape, as long as the walls are interconnected and / or intersect to provide mutual support, the mutual support providing resistance to matrix deformation and protecting the micro-columns under normal impact or wear when the device is in use. For those having about 18 to about 98 mN m -1For fluids with surface tension, these durable superomniphobic polymer devices can repel liquids with a liquid contact angle greater than or equal to 150°.

[0007] Another embodiment relates to a method of manufacturing the superomniphobic polymer device described above, wherein a fluid polymer is injected into a mold having negative features of the superomniphobic polymer device. After curing the fluid polymer, the superomniphobic polymer device wetted to the mold can be released to produce a durable superomniphobic polymer device. The mold can be formed around a master device having substantially the same shape as the superomniphobic polymer device, and the master device is removed from the mold. The master device can be formed by a 3D printing method, wherein a photosensitive resin or a plurality of metal particles are graded in a printer and a continuous solid device is formed, wherein the laser beam used by the printer has initiated the curing of the resin or the melting of the particles in the irradiated volume of the material at the level, and the level is the master device after removing the uncured resin or unmelted particles. Polydimethylsiloxane (PDMS) resin or any other material that can produce an elastic material can be used to form the mold around the master device. The mold is intended to be used multiple times before any need to replace the mold. A previously manufactured durable superomniphobic polymer device can be used as the master device for replacing or attaching the mold as needed in the absence of the original master or in addition to the original master.

[0008] The durable superomniphobic polymer device can be adhered, stuck, or otherwise fixed to a substrate device, which can be metal, polymer, ceramic, wood, paper, fabric, or glass. Description of the Drawings

[0009] Figure 1A shows a schematic diagram of a prior art device having a superhydrophobic surface in contact with water, and a scanning electron microscope (SEM) image of microcolumns that facilitate the formation of approximately spherical liquid beads of water or other high surface tension liquids.

[0010] Figure 1B shows a schematic diagram of a prior art superhydrophobic and superoleophobic (superomniphobic) device in contact with water or oil, and an SEM image of double-recessed microcolumns that facilitate the formation of approximately spherical liquid beads of water, other high surface tension liquids, hydrocarbon liquids, silicone liquids, or other low surface tension liquids to form approximately spherical liquid beads on the surface.

[0011] Figure 1C shows an SEM image of a prior art double-recessed microcolumn damaged due to mechanical wear.

[0012] Figure 1D shows a schematic diagram of a prior art superhydrophobic in contact with water, wherein the water is suspended by superhydrophobic nanostructures in the inverted pyramid-shaped cavities of a patterned robust substrate as a "protective armor".

[0013] Figure 2AShows a composite element of a durable superomniphobic surface according to one embodiment, where the double-recessed microcolumns provide liquid repellency and the interconnected armored substrate provides durability.

[0014] Figure 2B Top view of an SEM image showing the periodic arrangement of the fabricated double-recessed microcolumns.

[0015] Figure 2C SEM image of a cross-section of the wall of the interconnected armored substrate with its double-recessed structure.

[0016] Figure 3 Image of a superomniphobic surface device of PDMS rubber with high transparency according to one embodiment.

[0017] Figure 4A Photographs showing various liquid droplets according to one embodiment, where these liquid droplets exhibit contact angles on the superomniphobic surface of the plastic device.

[0018] Figure 4B Is a graph of the contact angles of water and silicone oil after a series of sandpaper abrasion cycles on a polymeric superomniphobic device including a durable superomniphobic surface according to one embodiment.

[0019] Figure 5 Is a schematic diagram of the steps for fabricating a polymeric device including a durable superomniphobic surface according to one embodiment.

[0020] Figure 6 Schematic diagram showing the use of a PVA-coated tray to print a master, where the master is printed from the top and the PVA is sacrificially dissolved to release the master. Detailed Description

[0021] The embodiments relate to a device having at least one component providing double-recessed microcolumns and at least a second component providing an interconnected double-recessed substrate, i.e., armor, protruding from the bottom surface to form a separated raised surface, the separated raised surface imparting resistance to normal impacts or abrasions during device use so as to maintain the superomniphobicity of the device. The microcolumns are located in cavities defined by the intersection or otherwise connection and mutual reinforcement of the walls forming the recessed substrate. Different from equivalent walls lacking a recessed structure, the recessed structure at the top of the wall maintains the superomniphobic nature of the surface.

[0022] The structure of each recessed micro-pillar is functionally equivalent to the structure illustrated in the side view of the prior art device in FIG. 1B. The cross-section of the recessed micro-pillar can be, but is not necessarily, circular, and its liquid contact diameter is about 1.5 to about 3 times the diameter of the support pillar. The liquid contact surface area of the recessed micro-pillar can occupy about three percent to about fifty percent of the surface. The height of the recessed micro-pillar can extend about 10 to about 70 μm from the bottom of the recess of the recessed matrix in which the recessed micro-pillar is located.

[0023] The height of the armored wall of the recessed matrix is equal to or greater than the height of the micro-pillar. For example, but not necessarily, the height of the armored wall of the recessed matrix is 1.01 to about 2 times the height of the micro-pillar. The recessed matrix resists deformation during impact and wear, such that the recessed micro-pillars within the recess are protected within the volume defined by the walls of the matrix. The matrix can have any pattern, such as square, rectangular, triangular, hexagonal, intersecting circles, intersecting ellipses, or any periodic, quasi-periodic, or random pattern of one or more shapes, such that the doubly recessed armored matrix can protect the recessed micro-pillars within the recess from damage due to normal wear or impact experienced when using a superomniphobic device. The construction material is a polymeric material that results in a device that is super-repellent to all liquids having a surface tension of about 18 to about 98 mN m -1 The protected doubly recessed matrix provides a robust and durable surface for the polymeric device. The durable superomniphobic device can be a sheet or any geometry having a structure for benefiting from its superomniphobicity, where the durable superomniphobic surface can be on an outer surface, such as but not limited to the outer surface of a building, furniture, tool, or appliance, or on an inner surface, such as but not limited to the inner surface of a tube or pipe.

[0024] As Figure 2A shown, the polymeric device having a durable superomniphobic surface includes doubly recessed micro-pillars having recesses, which, as illustrated, are defined as a square matrix by intersecting doubly recessed armored walls. As Figure 2B (top view) shows the exemplary distribution of the doubly recessed micro-pillars, which are formed to minimize the potential liquid-solid contact area for enhanced liquid repellency within the larger scale interconnected recessed armored matrix that serves to protect the recessed micro-pillars within the recess of the matrix. As Figure 2C shown, the doubly recessed cap located on the distal surface of the super-repellent armored wall prevents the penetration of local liquid along the matrix armor. This doubly recessed cap of the armor is an essential embodiment for achieving effective oil repellency for the durable superomniphobic device.

[0025] In an embodiment, the polymer can be a thermoplastic resin, such as but not limited to polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), copolyester terephthalate (Tritan), styrene acrylonitrile (SAN), polyacrylic acid (PAA), acrylonitrile butadiene styrene (ABS), nylon, polylactic acid (PLA), polybenzimidazole (PBI), polycarbonate (PC), polyetherimide (PEI), polyphenylene sulfide (PPS), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyurethane (PU), polytetrafluoroethylene, fluorinated poly(ethylene-co-propylene) (FEP) or any polymer that can be injection molded. Any available thermoplastic resin can be used for injection molding without any additives, or can contain additives to modify and supplement the properties, formation or fixation of the polymer as a superomniphobic device. The polymer can be a thermosetting resin, which can be reaction injection molded or any other molding method where a fluid polymer or prepolymer can flow into a mold and be fixed by chemical or physical association within the polymer. The thermosetting resin can be but not limited to polydimethylsiloxane (PDMS), polyester, vinyl ester, epoxy resin, phenolic resin, polyamide (PA) and bismaleimide (BMI). In an embodiment, a transparent polymer is used, resulting in a transparent or near-transparent device, as Figure 3 shown, where polydimethylsiloxane (PDMS) is used for the elastomeric superomniphobic device. By forming the device from any injection-moldable polymer, multiple superomniphobic devices can be manufactured relatively inexpensively.

[0026] The superomniphobic device formed in this way can be used by molding or can be laminated to the surface of a substrate device to form a composite device, where the superomniphobic device imparts superomniphobicity to the composite device. The substrate device can be a metal, polymer, wood, paper, fabric, ceramic or glass device, where the durable superomniphobic device adheres, sticks or otherwise mechanically attaches to at least a portion of the surface of the substrate device. As understood by those skilled in the art, the nature of the adhesion, sticking or fixing method can be any practice in the art for joining two defined solid surfaces.

[0027] These polymer superomniphobic devices have excellent repellency to various liquids, as Figure 4A illustrated by the fluid beads on the surface of the device in, where these liquids include but are not limited to hexane, heptane, ethanol, acetone, hexadecane, toluene, olive oil, soybean oil, glycerol and water. All of these liquids show a contact angle greater than 150°, indicating their super-repellency to form liquid beads that easily roll off the superomniphobic surface without any residue when tilted to a small angle of less than 5°. As Figure 4BAs shown, water and oil, such as silicone oil, maintain a high contact angle after hundreds of wear cycles, demonstrating the durability of the polymeric superomniphobic device.

[0028] According to one embodiment, injection molding can be used to fabricate a durable superomniphobic polymeric device. The manufacturing method is outlined in Figure 5 wherein: a master device with microcolumns and a recessed armor substrate is fabricated by 3D printing using a photosensitive resin or metal particles, which are patterned by curing or melting under the action of laser irradiation; polydimethylsiloxane (PDMS) resin is cast onto the master device and cured or gelled to form a PDMS mold around the master device, for example but not limited to at about 25 °C for about 24 hours; the PDMS mold is delaminated and peeled from the master device; a thermoplastic melt or a fluid thermosetting resin is injected into the PDMS mold; and the polymeric superomniphobic device is released from the reusable mold.

[0029] Depending on the 3D printing system, including a support tray for supporting the build during printing, the adhesion of the master, particularly the double-recessed armor, to the tray can be problematic and should be avoided or mitigated. For example, a stereolithography (SLA) 3D printer with at least 10 μm precision can be used to precisely fabricate the mold master, where a sacrificial layer is deposited on the tray, and the sacrificial layer can be removed by being broken as a layer without applying a load on the recessed structure. For example, the layer can be a layer that can be liquefied, for example, by dissolution and drainage from the formed superomniphobic structure. For example, as Figure 6 shown, a polyvinyl alcohol layer of about 1 to about 5 μm can be used as a support during printing and is subsequently dissolved in water, which easily detaches from the mold master. As Figure 6 shown, a top-to-bottom or superomniphobic layer device is advantageous in the layer-by-layer fabrication of the mold master, such that the recessed features are easily supported during fabrication.

[0030] The master device can be formed of a material different from that of the mold, and the master device can be a prefabricated polymeric superomniphobic device. Generally but not necessarily, a master device of a harder material relative to the material of the mold allows the mold to be cleanly removed from the master device, such that the mold can subsequently be used to produce multiple durable superomniphobic devices. Although an exemplary mold is formed by the gelling of PDMS resin, other rubber materials can be used to form the mold, provided that the mold material does not adhere to or deform the material of the master device or the polymeric material of the durable superomniphobic device during the molding process. When the durable superomniphobic device is an elastomeric device, the mold can be a rigid material, and the delamination of the elastomeric superomniphobic device can occur through the shape deformation of the elastomeric device during release from the rigid mold.

[0031] All patents, patent applications, provisional applications, and publications mentioned or cited herein are incorporated herein by reference in their entirety, including all drawings and tables, to the extent that they are not inconsistent with the explicit teachings of this specification.

[0032] It should be understood that the embodiments and implementations described herein are for illustrative purposes only, and various modifications or variations thereof will be suggested to those skilled in the art and will be included within the spirit and scope of this application. Additionally, any element or limitation of any invention or its implementation disclosed herein can be combined with any and / or all other elements or limitations (individually or in any combination) or any other invention or its implementation disclosed herein, and all such combinations are contemplated within the scope of the present invention without being limited thereto.

[0033] References

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Claims

1. A method of manufacturing a superomniphobic polymer device, which comprises: providing a mold for the superomniphobic polymer device, the superomniphobic polymer device comprising a plurality of double-recessed microcolumns located within a plurality of cavities separated within a substrate, the substrate comprising interconnected double-recessed walls having the microcolumns and the recessed mounting substrate; injecting a fluid polymer into the mold; curing the fluid polymer to produce the superomniphobic polymer device within the mold; and releasing the superomniphobic polymer device from the mold; wherein providing comprises: forming the mold around a master device, wherein the master device comprises the structure of the superomniphobic polymer device; and removing the master device from the mold; the method further comprises: grading a photosensitive resin or a plurality of metal particles within a 3D printer; irradiating the photosensitive resin or the plurality of metal particles with at least one laser beam; curing the volume of the photosensitive resin or melting the volume of the plurality of metal particles irradiated by the laser beam to form a master device; and isolating the master device from the photosensitive resin or the plurality of metal particles not irradiated by the laser beam.

2. The method according to claim 1, wherein forming the mold comprises: casting polydimethylsiloxane (PDMS) resin around the master device; gelling the polydimethylsiloxane (PDMS) resin to form a mold around the master device; and removing the master device from the mold.

3. The method according to claim 2, wherein removing is delaminating or peeling the mold from the master device.

4. The method according to claim 1, wherein the master device is a previously manufactured superomniphobic polymer device.

5. The method according to claim 1, wherein the mold is reusable.

6. The method according to claim 1, wherein the polymer comprises a thermoplastic resin.

7. The method according to claim 6, wherein the thermoplastic resin is polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), copolyester terephthalate (Tritan), styrene acrylonitrile (SAN), polyacrylic acid (PAA), acrylonitrile butadiene styrene (ABS), nylon, polylactic acid (PLA), polybenzimidazole (PBI), polycarbonate (PC), polyetherimide (PEI), polyphenylene sulfide (PPS), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyurethane (PU), polytetrafluoroethylene or fluorinated poly(ethylene-co-propylene) (FEP).

8. The method according to claim 1, wherein the polymer comprises a thermosetting resin.

9. The method according to claim 8, wherein the thermosetting resin is polydimethylsiloxane (PDMS), polyester, vinyl ester, epoxy resin, phenolic resin, polyamide (PA) and bismaleimide (BMI).

10. The method according to claim 1, wherein the polymer contains additives.

11. The method according to claim 10, wherein the additives are one or more of a catalyst, a particulate filler or a stabilizer.

12. The method according to claim 1, wherein the double-recessed substrate comprises a pattern that is periodic, quasi-periodic, random, or any combination thereof.

13. The method according to claim 1, wherein the double-recessed substrate comprises a pattern that includes squares, rectangles, triangles, hexagons, intersecting circles, or intersecting ellipses.

14. The method according to claim 1, wherein the liquid contact angle of a fluid having a surface tension of 18 to 98 mN m -1 is greater than or equal to 150°.

15. The method according to claim 1, further comprising laminating the superomniphobic polymer device to a substrate device.

16. The method according to claim 15, wherein the substrate device comprises metal, polymer, ceramic, wood, paper, fabric, or glass.

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