Improved silicone articles

Abstract

There is described an article comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a silicone rubber, wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 1 µm.

Description

[0001] Improved Silicone Articles

[0002] Field

[0003] The present disclosure relates to silicone rubber articles, specifically silicone rubber articles comprising nanofibers, vent assemblies comprising the silicone rubber article and devices comprising the same.

[0004] Background

[0005] It is known in the art that microporous fluoropolymer membranes are useful in a variety of applications. Articles made from microporous fluoropolymer membranes possess properties such as toughness, impact strength, low coefficient of friction, and resistance to attack by solvents and corrosive chemicals. Because of the favorable attributes associated with microporous fluoropolymer membranes, microporous fluoropolymer membranes have been utilized in a variety of applications, such as water filtration, dialysis, battery separators, vents, desalinization, and gas separation.

[0006] For example, electronic devices that comprise acoustic transducers such as speakers and microphones often comprise vents or vent assemblies that protect such acoustic transducers from the contact with contaminants such as particulates or liquids. Such vents or vent assemblies typically occlude an aperture in the housing of the electronic device through which sound travels from or to the speaker or microphone respectively. Additionally, electronic devices also often incorporate pressure vents, which provide similar functionality in that they prevent the ingress of particulates and liquids from entering and damaging sensitive components but are not necessarily required to transmit sound.

[0007] The materials used to make up the vents or vent assemblies are required to be resistant to the passage of particulates and liquids, especially liquid water, whilst also maximising the transmission of sound through them.

[0008] Typically, in order to ensure that the interior of the electronic device is adequately protected from particulates and liquids in a manner that is robust to typical device usage, the membrane of the vent or vent assembly is tailored to prevent ingress of particulates and liquids whilst trying to minimise the degradation of these protection properties after the vent assembly is challenged with high water pressure (such as may happen with accidental submersion of the device) or chemical contamination (such as may happen if the device comes into contact with soapy water, e.g.). However, the properties of new electronic devices are required to constantly be improving by the expectations of users whilst also ensuring that these electronic devices become more durable and resistant to damage due to ingress of liquids and particulates.

[0009] Accordingly, there remains a need for improved vents and vent assemblies that have improved performance, including performance that does not degrade when the vent and vent assemblies are challenged.

[0010] Furthermore, as described above, articles such as vents and vent assemblies often use fluoropolymer membranes which belong to a class of materials known as per- or polyfluoroalkyl substances (PFAS). PFAS materials may provide superior performance, but may be subject to use restrictions as a result of pending legislation in various jurisdictions that may preclude their use in such applications.

[0011] Accordingly, it is desirable to provide articles such as vents and vent assemblies that do not incorporate fluoropolymer membranes and that have comparable or superior performance.

[0012] Further, fluoropolymers have been used in other applications and it remains desirable to provide alternative or improved materials that can replace fluoropolymers to provide comparable or superior performance.

[0013] The present disclosure is intended at least in part to address at least one of these issues.

[0014] Summary

[0015] According to a first embodiment there is provided an article comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a silicone rubber. The nanofibers of the plurality of nanofibers may have a mean diameter of less than 1 μm.

[0016] The nanofibers of the plurality of nanofibers may comprise a secondary polymer. The term “secondary polymer” as used herein refers to a polymer that is not a silicone polymer and is in addition to the silicone rubber of the nanofibers of the plurality of nanofibers. Typically, the secondary polymer corresponds to a minor component of the nanofibers of the plurality of nanofibers.

[0017] The nanofibers of the plurality of nanofibers may comprise from 1% to 25% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 20% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to from 1% to 10% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 9% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 8% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 7% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 6% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 5% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 2% to 10% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 3% to 10% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 4% to 10% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 2% to 25% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 3% to 25% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 4% to 25% of the secondary polymer.

[0018] The secondary polymer may be a thermoplastic polymer. The secondary polymer may be poly(methyl methacrylate) (PMMA) or a copolymer comprising PMMA. The secondary polymer may comprise polyurethane, polyamide, polylactic acid, polycarbonate, polyether sulfone, polyether ether ketone (PEEK), polyetherimide (PEI), polyethylene, polypropylene, polyphenylene sulfide (PPS), polyacrylate, polyethylene glycol (PEG), polyvinylacetate (PVA) acrylonitril butadien stytrene (ABS), polyvinyl chloride (PVC) or polystyrene. The secondary polymer may comprise PMMA, polystyrene, or PVC.

[0019] The secondary polymer may comprise PMMA. The secondary polymer may comprise high molecular weight PMMA. High molecular weight PMMA may have an average molecular weight of at least 300,000 g / mol. High molecular weight PMMA may have an average molecular weight of at least 500,000 g / mol. High molecular weight PMMA may have an average molecular weight of at least 700,000 g / mol. High molecular weight PMMA may have an average molecular weight of at least 900,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 300,000 to 3,000,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 500,000 to 3,000,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 700,000 to 3,000,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 900,000 to 3,000,000 g / mol. The high molecular weight PMMA may have an average molecular weight of from 300,000 g / mol to 2,000,000 g / mol. The high molecular weight PMMA may have an average molecular weight of from 300,000 g / mol to 1,500,000 g / mol. The high molecular weight PMMA may have an average molecular weight of from 300,000 g / mol to 1,000,000 g / mol.

[0020] In some embodiments there is provided an article comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a silicone rubber and from 1% to 10% poly(methyl methacrylate) (PMMA), wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 1 μm.

[0021] As used herein, the term “silicone rubber” refers to a material made of cross-linked polymer chains where the polymer chains comprise a silicon-oxygen backbone.

[0022] The nanofibers of the plurality of nanofibers may have a mean diameter of less than 0.9 μm. The nanofibers of the plurality of nanofibers may have a mean diameter of less than 0.8 μm. The nanofibers of the plurality of nanofibers may have a mean diameter of less than 0.75 μm. The nanofibers of the plurality of nanofibers may have a mean diameter of less than 0.7 μm.

[0023] The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.1 μm to 0.9 μm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.1 μm to 0.8 μm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.1 μm to 0.75 μm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.1 μm to 0.7 μm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.2 μm to 0.9 μm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.3 μm to 0.9 μm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.4 μm to 0.9 μm.

[0024] The nanofibers of the plurality of nanofibers may be connected together. The nanofibers of the plurality of nanofibers may be bonded or fused together to form the article. In embodiments where the nanofibers of the plurality of nanofibers are fused together the article may be more compact and / or stronger than articles where the nanofibers of the plurality of nanofibers are not fused together.

[0025] The article may be a nonwoven article.

[0026] The silicone rubber may be a high molecular weight silicone rubber (HMWS rubber). HMWS rubber may be referred to as “solid silicone rubber”. The HMWS rubber may have an average molecular weight of at least 100,000 g / mol. The HMWS rubber may have an average molecular weight of at least 200,000 g / mol. The HMWS rubber may have an average molecular weight of at least 300,000 g / mol. The HMWS rubber may have an average molecular weight of at least 400,000 g / mol. The HMWS rubber may have an average molecular weight of from 100,000 g / mol to 1,500,000 g / mol. The HMWS rubber may have an average molecular weight of from 200,000 g / mol to 1,500,000 g / mol. The HMWS rubber may have an average molecular weight of from 300,000 g / mol to 1,500,000 g / mol. The HMWS rubber may have an average molecular weight of from 400,000 g / mol to 1,500,000 g / mol. The HMWS rubber may have an average molecular weight of from 100,000 g / mol to 1,000,000 g / mol. The HMWS rubber may have an average molecular weight of from 100,000 g / mol to 750,000 g / mol.

[0027] The silicone rubber may comprise polydimethylsiloxane (PDMS), polymethylvinylsiloxane (PMVS), polymethylphenylsiloxane (PMPS), fluorosilicone rubber (FVMQ), functionalised PDMS or a copolymer thereof.

[0028] In some embodiments the silicone rubber may comprise PDMS. The silicone rubber may comprise a copolymer of PDMS and PMVS. In other words, the silicone rubber may comprise a polymer formed from dimethyl siloxane and methylvinyl siloxane monomers such that the polymer comprises a siloxane backbone with both dimethyl and methylvinyl groups along the backbone chain. The copolymer may predominantly comprise PDMS with a minor portion of the copolymer comprising PMVS. For example, the copolymer may comprise less than 1% PMVS or less than 0.5% PMVS.

[0029] The silicone rubber may comprise functionalised PDMS. The functionalised PDMS may comprise a PDMS polymer functionalised to include at least one functional group. The functional group may be configured to form a crosslink between PDMS polymers. The functional group may be configured to form a crosslink between PDMS polymers when exposed to a curing process. The silicone rubber may have been cured in a curing process using a curing agent. The curing agent may be a metal catalyst such as metallic platinum, for example. The curing agent may be peroxide. The curing agent may be activated by exposure to a curing condition. The curing condition may be exposure to elevated temperatures or heat. The curing condition may be exposure to a curing wavelength of light. The curing wavelength of light may be an ultraviolet wavelength of light (100 nm to 400 nm).

[0030] The article may have a mass per area of less than or equal to 40 gsm (g / m2). The article may have a mass per area or less than 35 gsm. The article may have a mass per area or less than 30 gsm. The article may have a mass per area or less than 29 gsm. The article may have a mass per area or less than 28 gsm. The article may have a mass per area or less than 27 gsm. The article may have a mass per area or less than 26 gsm. The article may have a mass per area or less than 25 gsm.

[0031] The article may have a mass per area of from 1 gsm to 40 gsm. The article may have a mass per area of from 1 gsm to 35 gsm. The article may have a mass per area of from 1 gsm to 30 gsm. The article may have a mass per area of from 1 gsm to 29 gsm. The article may have a mass per area of from 1 gsm to 28 gsm. The article may have a mass per area of from 1 gsm to 27 gsm. The article may have a mass per area of from 1 gsm to 26 gsm. The article may have a mass per area of from 1 gsm to 25 gsm.

[0032] The article may have a bubble point of at least 0.1 bar. The article may have a bubble point of at least 0.15 bar. The article may have a bubble point of at least 0.2 bar. The article may have a bubble point of at least 0.3 bar. The article may have a bubble point of at least 0.4 bar. The article may have a bubble point of at least 0.5 bar. The article may have a bubble point of at least 0.6 bar.

[0033] The article may have a bubble point of from 0.1 bar to 3 bar. The article may have a bubble point of from 0.2 bar to 3 bar. The article may have a bubble point of from 0.3 bar to 3 bar. The article may have a bubble point of from 0.4 bar to 3 bar. The article may have a bubble point of from 0.5 bar to 3 bar. The article may have a bubble point of from 0.6 bar to 3 bar. The article may have a bubble point of from 0.2 bar to 2.5 bar. The article may have a bubble point of from 0.1 bar to 2 bar. The article may have a bubble point of from 0.1 bar to 1.5 bar. The article may have a bubble point of from 0.2 bar to 2 bar. The article may have a bubble point of from 0.2 bar to 1.5 bar.

[0034] The article may have a maximum pore size of less than 5 μm. The article may have a maximum pore size of less than 4 μm. The article may have a maximum pore size of less than 3 μm. The article may have a maximum pore size of less than 2.5 μm. The article may have a maximum pore size of less than 2 μm. The article may have a maximum pore size of less than 1.5 μm. The article may have a maximum pore size of less than 1.25 μm.

[0035] The article may have a maximum pore size from 0.05 to 5 μm. The article may have a maximum pore size from 0.05 to 4 μm. The article may have a maximum pore size from 0.05 to 3 μm. The article may have a maximum pore size from 0.05 to 2.5 μm. The article may have a maximum pore size from 0.05 to 2 μm. The article may have a maximum pore size from 0.05 to 1.5 μm. The article may have a maximum pore size from 0.05 to 1.25 μm. The article may have a maximum pore size from 0.1 to 5 μm. The article may have a maximum pore size from 0.2 to 5 μm. The article may have a maximum pore size from 0.3 to 5 μm. The article may have a maximum pore size from 0.4 to 5 μm. The article may have a maximum pore size from 0.5 to 5 μm. The article may have a maximum pore size from 0.6 to 5 μm. The article may have a maximum pore size from 0.7 to 5 μm. The article may have a maximum pore size from 0.8 to 5 μm. The article may have a maximum pore size from 0.1 to 3 μm. The article may have a maximum pore size from 0.2 to 3 μm. The article may have a maximum pore size from 0.3 to 3 μm. The article may have a maximum pore size from 0.4 to 3 μm. The article may have a maximum pore size from 0.5 to 3 μm. The article may have a maximum pore size from 0.6 to 3 μm. The article may have a maximum pore size from 0.7 to 3 μm. The article may have a maximum pore size from 0.8 to 3 μm.

[0036] The article may have a porosity of at least 10%. The article may have a porosity of at least 20%. The article may have a porosity of at least 30%. The article may have a porosity of from 10% to 90%. The article may have a porosity of from 10% to 80%. The article may have a porosity of from 10% to 70%. The article may have a porosity of from 10% to 60%. The article may have a porosity of from 10% to 50%. The article may have a porosity of from 20% to 50%. The article may have a porosity of from 30% to 50%. The article may have a porosity of from 10% to 40%.

[0037] The article may be substantially planar. Accordingly, the article may predominantly extend in the x and y plane. The article may be a membrane. The article may be a film. The article may be in the form of a sheet.

[0038] The article may have a thickness of less than or equal to 100 μm. The article may have a thickness of less than or equal to 75 μm. The article may have a thickness of less than or equal to 50 μm. The article may have a thickness of less than or equal to 45 μm. The article may have a thickness of less than or equal to 40 μm. The article may have a thickness of less than or equal to 35 μm. The article may have a thickness of less than or equal to 30 μm.

[0039] The article may have a thickness of from 1 μm to 100 μm. The article may have a thickness of from 1 μm to 75 μm. The article may have a thickness of from 1 μm to 50 μm. The article may have a thickness of from 5 μm to 50 μm. The article may have a thickness of from 5 μm to 45 μm. The article may have a thickness of from 5 μm to 40 μm. The article may have a thickness of from 5 μm to 35 μm. The article may have a thickness of from 5 μm to 30 μm. The article may have a thickness of from 10 μm to 50 μm. In embodiments where the article is substantially planar, the thickness of the article will be understood to be the dimension normal to the plane of the article.

[0040] The nanofibers of the plurality of nanofibers may comprise a filler material. Typically, the filler material is distributed throughout the polymer matrix of the nanofibers of the plurality of nanofibers. The filler material may be configured to strengthen or reinforce the nanofibers of the plurality of nanofibers. The filler material may be configured to increase the resistance of the nanofibers of the plurality of nanofibers to chemical reaction or thermal break down.

[0041] The filler material may comprise silica, fumed silica, precipitated silica, glass, quartz, titanium dioxide, graphene, carbon black, color pigments, or a natural clay material such as montmorillonite.

[0042] In some embodiments the filler material may comprise fumed silica.

[0043] The nanofibers of the plurality of nanofibers may comprise at least 20% filler material by weight. The nanofibers of the plurality of nanofibers may comprise at least 30% filler material by weight. The nanofibers of the plurality of nanofibers may comprise at least 40% filler material by weight. The nanofibers of the plurality of nanofibers may comprise at least 50% filler material by weight. The nanofibers of the plurality of nanofibers may comprise from 20% to 75% filler material by weight. The nanofibers of the plurality of nanofibers may comprise from 20% to 70% filler material by weight. The nanofibers of the plurality of nanofibers may comprise from 20% to 60% filler material by weight. The nanofibers of the plurality of nanofibers may comprise from 20% to 50% filler material by weight. The nanofibers of the plurality of nanofibers may comprise from 30% to 75% filler material by weight. The nanofibers of the plurality of nanofibers may comprise from 40% to 75% filler material by weight.

[0044] The article may have an elongation to break of at least 100%. The article may have an elongation to break of at least 110%. The article may have an elongation to break of at least 120%. The article may have an elongation to break of at least 130%.

[0045] The article may have an elongation to break of from 100% to 500%. The article may have an elongation to break of from 110% to 500%. The article may have an elongation to break of from 120% to 500%. The article may have an elongation to break of from 130% to 500%.

[0046] An elongation to break as referenced herein may also be referred to as an elongation at maximum force and are used herein interchangeably. The article may be flexible. The article may be configured to be wrapped around an object to form a covering over that object.

[0047] The article may be formed using electrospinning. Suitable methods of electrospinning may include needle-based electrospinning, wire-based electrospinning, air assisted electrospinning, ultrasonic electrospinning or roller electrospinning. The article may be formed using rotary jet spinning.

[0048] In some embodiments, the article may comprise a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a silicone rubber and from 1% to 10% poly(methyl methacrylate) (PMMA), wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 1 μm, wherein the article is formed by electrospinning.

[0049] In some embodiments, the article may comprise a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a high molecular weight silicone rubber and from 1 % to 10% poly(methyl methacrylate) (PMMA), wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 1 μm, wherein the article is formed by electrospinning.

[0050] In some embodiments, the article may comprise a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a silicone rubber and from 1% to 10% poly(methyl methacrylate) (PMMA), wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 1 μm, wherein the nanofibers of the plurality of nanofibers comprise polydimethylsiloxane (PDMS), functionalised PDMS, or a copolymer of PDMS and the article is formed by electrospinning.

[0051] In some embodiments, the article may comprise a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a high molecular weight silicone rubber and from 1 % to 10% poly(methyl methacrylate) (PMMA), wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 1 μm, wherein the high molecular weight silicone rubber comprises polydimethylsiloxane (PDMS), functionalised PDMS, or a copolymer of PDMS and the article is formed by electrospinning.

[0052] The article may be stable at high temperatures. The article may be stable at temperatures up to 300°C. The article may be stable at temperatures up to 280°C. The article may be stable at temperatures up to 260°C. The article may have a reduction in airflow through the article of less than 15% after exposure to high temperatures. The article may have a reduction in airflow through the article of less than 15% after exposure to 260°C. The article may have a reduction in airflow through the article of less than 10% after exposure to 260°C.

[0053] The article may have a reduction in airflow through the article of less than 0.5 L / hr after exposure to 260°C. The reduction in airflow through the article will be understood to be as measured using the method described herein below. The article may have a reduction in airflow through the article of less than 0.4 L / hr after exposure to 260°C. The article may have a reduction in airflow through the article of less than 0.3 L / hr after exposure to 260°C. The article may have a reduction in airflow through the article of less than 0.2 L / hr after exposure to 260°C. The article may have a reduction in airflow through the article of less than 0.1 L / hr after exposure to 260°C.

[0054] In a second aspect there is provided a method of forming an article comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a silicone rubber, the method comprising the steps:

[0055] providing a silicone material;

[0056] adding the silicone material to a solvent to form a precursor solution;

[0057] solution spinning the precursor solution to form a mat of nanofibers; and

[0058] curing the silicone in the mat of nanofibers to silicone rubber to form an article.

[0059] Typically, the silicone material is a high molecular weight silicone (HMWS) material. Therefore, the method may be a method of forming an article comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a HMWS rubber, the method comprising the steps:

[0060] providing a HMWS material;

[0061] adding the HMWS material to a solvent to form a precursor solution;

[0062] solution spinning the precursor solution to form a mat of nanofibers; and

[0063] curing the HMWS in the mat of nanofibers to HMWS rubber to form an article.

[0064] The HMWS material may have an average molecular weight of at least 100,000 g / mol. The HMWS material may have an average molecular weight of at least 200,000 g / mol. The HMWS material may have an average molecular weight of at least 300,000 g / mol. The HMWS material may have an average molecular weight of at least 400,000 g / mol. The HMWS material may have an average molecular weight of from 100,000 g / mol to 1,500,000 g / mol. The HMWS material may have an average molecular weight of from 200,000 g / mol to 1,500,000 g / mol. The HMWS material may have an average molecular weight of from 300,000 g / mol to 1,500,000 g / mol. The HMWS material may have an average molecular weight of from 400,000 g / mol to 1,500,000 g / mol. The HMWS material may have an average molecular weight of from 100,000 g / mol to 1,000,000 g / mol. The HMWS material may have an average molecular weight of from 100,000 g / mol to 750,000 g / mol.

[0065] The HMWS material may have a viscosity of more than 20 cP when solvated in methyl ethyl ketone (MEK) at 20% polymer by weight. The HMWS material may have a viscosity of more than 50 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 100 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 150 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 200 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 250 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 300 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 350 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 400 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 450 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 500 cP when solvated in MEK at 20% polymer by weight. The HMWS material may have a viscosity of more than 600 cP when solvated in MEK at 20% polymer by weight.

[0066] The viscosity of the HMWS material when solvated in MEK is as measured using the method described below and is provided as a standardised way of comparing the viscosity of the material to other materials.

[0067] The HMWS material may comprise polydimethylsiloxane (PDMS), polymethylvinylsiloxane (PMVS), polymethylphenylsiloxane (PMPS), fluorosilicone (FVMQ), functionalised PDMS, or copolymers thereof.

[0068] In some embodiments the HMWS may comprise PDMS. The HMWS may comprise a copolymer of PDMS and PMVS. In other words the silicone rubber may comprise a polymer formed from dimethyl siloxane and methylvinyl siloxane monomers such that the polymer comprises a siloxane backbone with both dimethyl and methylvinyl groups alone the backbone chain. The copolymer may predominantly comprise PDMS with a minor portion of the copolymer comprising PMVS. For example, the copolymer may comprise less than 1% PMVS. The HMWS may comprise functionalised PDMS. The functionalised PDMS may comprise a PDMS polymer functionalised to include at least one functional group. The functional group may be configured to form a crosslink between PDMS polymers. The functional group may be configured to form a crosslink between PDMS polymers when exposed to a curing process. The HMWS may have been cured in a curing process using a curing agent. The curing agent may be a metal catalyst such as metallic platinum, for example. The curing agent may be peroxide. The curing agent may be activated by exposure to a curing condition. The curing condition may be exposure to elevated temperatures or heat. The curing condition may be exposure to a curing wavelength of light. The curing wavelength of light may be an ultraviolet wavelength of light (100 nm to 400 nm).

[0069] The HMWS material may comprise a filler material. Accordingly, the precursor solution comprises the filler material. The filler material may be configured to strengthen or reinforce the nanofibers of the plurality of nanofibers formed using the present method. The filler material may be configured to increase the resistance of the nanofibers of the plurality of nanofibers formed using the present method to chemical reaction or thermal break down.

[0070] The filler material may comprise silica, fumed silica, precipitated silica, glass, quartz, titanium dioxide, graphene, carbon black, color pigments, or a natural clay material such as montmorillonite.

[0071] For example, the filler material may comprise fumed silica.

[0072] The HMWS material may comprise at least 20% filler material by weight. The HMWS material may comprise at least 30% filler material by weight. The HMWS material may comprise at least 40% filler material by weight. The HMWS material may comprise at least 50% filler material by weight. The HMWS material may comprise from 20% to 75% filler material by weight. The HMWS material may comprise from 20% to 70% filler material by weight. The HMWS material may comprise from 20% to 60% filler material by weight. The HMWS material may comprise from 20% to 50% filler material by weight. The HMWS material may comprise from 30% to 75% filler material by weight. The HMWS material may comprise from 40% to 75% filler material by weight.

[0073] The precursor solution may comprise at least 20% filler material by weight. The precursor solution may comprise at least 30% filler material by weight. The precursor solution may comprise at least 40% filler material by weight. The precursor solution may comprise at least 50% filler material by weight. The precursor solution may comprise from 20% to 75% filler material by weight. The precursor solution may comprise from 20% to 70% filler material by weight. The precursor solution may comprise from 20% to 60% filler material by weight. The precursor solution may comprise from 20% to 50% filler material by weight. The precursor solution may comprise from 30% to 75% filler material by weight. The precursor solution may comprise from 40% to 75% filler material by weight.

[0074] The precursor solution may comprise a secondary polymer. The precursor solution may comprise from 1% to 25% of the secondary polymer. For the avoidance of doubt, the percentage of the secondary polymer in the precursor solution is the percentage of dry polymer masses absent solvent. The precursor solution may comprise from 1 % to 20% of the secondary polymer. The precursor solution may comprise from 1% to 15% of the secondary polymer. The precursor solution may comprise from 1% to 10% of the secondary polymer. The precursor solution may comprise from 1 % to 9% of the secondary polymer. The precursor solution may comprise from 1% to 8% of the secondary polymer. The precursor solution may comprise from 1% to 7% of the secondary polymer. The precursor solution may comprise from 1% to 6% of the secondary polymer. The precursor solution may comprise from 1% to 5% of the secondary polymer. The precursor solution may comprise from 2% to 10% of the secondary polymer. The precursor solution may comprise from 3% to 10% of the secondary polymer. The precursor solution may comprise from 4% to 10% of the secondary polymer. The precursor solution may comprise from 2% to 25% of the secondary polymer. The precursor solution may comprise from 3% to 25% of the secondary polymer. The precursor solution may comprise from 4% to 25% of the secondary polymer.

[0075] The secondary polymer may be a thermoplastic polymer.

[0076] The secondary polymer may be poly(methyl methacrylate) (PMMA) or a copolymer comprising PMMA. The secondary polymer may comprise polyurethane, polyamide, polylactic acid, polycarbonate, polyether sulfone, polyether ether ketone (PEEK), polyetherimide (PEI), polyethylene, polypropylene, polyphenylene sulfide (PPS), polyacrylate, polyethylene glycol (PEG), polyvinylacetate (PVA), acrylonitril butadien stytrene (ABS), polyvinyl chloride (PVC) or polystyrene. The secondary polymer may comprise PMMA, polystyrene, or PVC.

[0077] The secondary polymer may comprise PMMA. The secondary polymer may comprise high molecular weight PMMA. High molecular weight PMMA may have an average molecular weight of at least 300,000 g / mol. High molecular weight PMMA may have an average molecular weight of at least 500,000 g / mol. High molecular weight PMMA may have an average molecular weight of at least 700,000 g / mol. High molecular weight PMMA may have an average molecular weight of at least 900,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 300,000 to 3,000,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 500,000 to 3,000,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 700,000 to 3,000,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 900,000 to 3,000,000 g / mol. The high molecular weight PMMA may have an average molecular weight of from 300,000 g / mol to 2,000,000 g / mol. The high molecular weight PMMA may have an average molecular weight of from 300,000 g / mol to 1,500,000 g / mol. The high molecular weight PMMA may have an average molecular weight of from 300,000 g / mol to 1,000,000 g / mol.

[0078] The step of solution spinning may be electrospinning. Suitable methods of electrospinning may include needle-based electrospinning, wire-based electrospinning, air assisted electrospinning, ultrasonic electrospinning or roller electrospinning. The step of solution spinning may be rotary jet spinning.

[0079] The nanofibers of the plurality of nanofibers may fuse together during the step of spinning. The nanofibers may fuse together as the mat of nanofibers is formed. The method may comprise a step of fusing the nanofibers of the plurality of nanofibers together. The step of fusing the nanofibers of the plurality of nanofibers together may be carried out after the step of forming a mat of nanofibers. The step of fusing the nanofibers of the plurality of nanofibers together may be carried out after the step of forming a mat of nanofibers and before the step of curing the silicone in the mat of nanofibers to silicone rubber to form an article. The step of fusing the nanofibers of the plurality of nanofibers together may include a rest period. The rest period may correspond to not carrying out any action on the mat of nanofibers for a period of time. The rest period may be at least 1 minute. The rest period may be at least 10 minutes. The rest period may be at least 20 minutes. The rest period may be at least 30 minutes.

[0080] The precursor solution may have a conductivity of at least 10 µS / cm. The precursor solution may have a conductivity of at least 15 µS / cm. The precursor solution may have a conductivity of at least 20 µS / cm. The precursor solution may have a conductivity of from 10 to 50 µS / cm. The precursor solution may have a conductivity of from 15 to 50 µS / cm. The precursor solution may have a conductivity of from 20 to 50 µS / cm.

[0081] The precursor solution may comprise a component that increases to conductivity of the precursor solution. For example, the precursor solution may comprise a salt such as tetraethylammonium bromide (TEAB). According to a third aspect there is provided a vent comprising the article of the first aspect or the article formed by the method of the second aspect.

[0082] In a fourth aspect there is provided a vent assembly comprising a membrane and at least one adhesive layer, the membrane comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising silicone rubber.

[0083] The membrane may be an article of the first aspect or an article made by the method of the second aspect.

[0084] The at least one adhesive layer may define an aperture. The aperture may expose the membrane such that a portion of the membrane is not covered by the at least one adhesive layer.

[0085] The nanofibers of the plurality of nanofibers may comprise a secondary polymer.

[0086] The nanofibers of the plurality of nanofibers may comprise from 1% to 25% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 20% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 15% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 10% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 9% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 8% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 7% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 6% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 1% to 5% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 2% to 10% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 3% to 10% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 4% to 10% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 2% to 25% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 3% to 25% of the secondary polymer. The nanofibers of the plurality of nanofibers may comprise from 4% to 25% of the secondary polymer. The secondary polymer may be a thermoplastic polymer. The secondary polymer may be poly(methyl methacrylate) (PMMA) or a copolymer comprising PMMA. The secondary polymer may comprise polyurethane, polyamide, polylactic acid, polycarbonate, polyether sulfone, polyether ether ketone (PEEK), polyetherimide (PEI), polyethylene, polypropylene, polyphenylene sulfide (PPS), polyacrylate, polyethylene glycol (PEG), polyvinylacetate (PVA), acrylonitril butadien stytrene (ABS), polyvinyl chloride (PVC) or polystyrene. The secondary polymer may comprise PMMA, polystyrene, or PVC.

[0087] The secondary polymer may comprise PMMA. The secondary polymer may comprise high molecular weight PMMA. High molecular weight PMMA may have an average molecular weight of at least 300,000 g / mol. High molecular weight PMMA may have an average molecular weight of at least 500,000 g / mol. High molecular weight PMMA may have an average molecular weight of at least 700,000 g / mol. High molecular weight PMMA may have an average molecular weight of at least 900,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 300,000 to 3,000,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 500,000 to 3,000,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 700,000 to 3,000,000 g / mol. High molecular weight PMMA may have an average molecular weight of from 900,000 to 3,000,000 g / mol. The high molecular weight PMMA may have an average molecular weight of from 300,000 g / mol to 2,000,000 g / mol. The high molecular weight PMMA may have an average molecular weight of from 300,000 g / mol to 1,500,000 g / mol. The high molecular weight PMMA may have an average molecular weight of from 300,000 g / mol to 1,000,000 g / mol.

[0088] In some embodiments there is provided a vent assembly comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a silicone rubber and from 1% to 10% PMMA, wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 1 μm.

[0089] The nanofibers of the plurality of nanofibers may have a mean diameter of less than 0.9 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of less than 0.85 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of less than 0.8 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of less than 0.75 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of less than 0.7 pm.

[0090] The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.1 pm to 0.9 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.1 pm to 0.85 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.1 pm to 0.8 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.1 pm to 0.75 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.1 pm to 0.7 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.2 pm to 0.9 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.3 pm to 0.9 pm. The nanofibers of the plurality of nanofibers may have a mean diameter of from 0.4 pm to 0.9 pm.

[0091] The nanofibers of the plurality of nanofibers may be connected together. The nanofibers of the plurality of nanofibers may be bonded or fused together to form the article. In embodiments where the nanofibers of the plurality of nanofibers are fused together the article may be more compact and / or stronger than articles where the nanofibers of the plurality of nanofibers are not fused together.

[0092] The silicone rubber may be a high molecular weight silicone rubber (HMWS rubber). HMWS rubber may be referred to as “solid silicone rubber”. The HMWS rubber may have an average molecular weight of at least 100,000 g / mol. The HMWS rubber may have an average molecular weight of at least 200,000 g / mol. The HMWS rubber may have an average molecular weight of at least 300,000 g / mol. The HMWS rubber may have an average molecular weight of at least 400,000 g / mol. The HMWS rubber may have an average molecular weight of from 100,000 g / mol to 2,000,000 g / mol. The HMWS rubber may have an average molecular weight of from 200,000 g / mol to 2,000,000 g / mol. The HMWS rubber may have an average molecular weight of from 300,000 g / mol to 2,000,000 g / mol. The HMWS rubber may have an average molecular weight of from 400,000 g / mol to 2,000,000 g / mol. The HMWS rubber may have an average molecular weight of from 100,000 g / mol to 1,500,000 g / mol. The HMWS rubber may have an average molecular weight of from 100,000 g / mol to 1,000,000 g / mol. The HMWS rubber may have an average molecular weight of from 100,000 g / mol to 750,000 g / mol.

[0093] The silicone rubber may comprise polydimethylsiloxane (PDMS), polymethylvinylsiloxane (PMVS), polymethylphenylsiloxane (PMPS), fluorosilicone rubber (FVMQ), functionalised PDMS or copolymers thereof.

[0094] In some embodiments the silicone rubber may comprise PDMS. The silicone rubber may comprise a copolymer of PDMS and PMVS. The silicone rubber may comprise functionalised PDMS. The functionalised PDMS may comprise a PDMS polymer functionalised to include at least one functional group. The functional group may be configured to form a crosslink between PDMS polymers. The functional group may be configured to form a crosslink between PDMS polymers when exposed to a curing process. The silicone rubber may have been cured in a curing process using a curing agent. The curing agent may be a metal catalyst such as metallic platinum, for example. The curing agent may be peroxide. The curing agent may be activated by exposure to a curing condition. The curing condition may be exposure to elevated temperatures or heat. The curing condition may be exposure to a curing wavelength of light. The curing wavelength of light may be an ultraviolet wavelength of light (100 nm to 400 nm).

[0095] The membrane may have a mass per area of less than or equal to 40 gsm (g / m2). The membrane may have a mass per area or less than 35 gsm. The membrane may have a mass per area or less than 30 gsm. The membrane may have a mass per area or less than 29 gsm. The membrane may have a mass per area or less than 28 gsm. The membrane may have a mass per area or less than 27 gsm. The membrane may have a mass per area or less than 26 gsm. The membrane may have a mass per area or less than 25 gsm.

[0096] The membrane may have a mass per area of from 1 gsm to 40 gsm. The membrane may have a mass per area of from 1 gsm to 35 gsm. The membrane may have a mass per area of from 1 gsm to 30 gsm. The membrane may have a mass per area of from 1 gsm to 29 gsm. The membrane may have a mass per area of from 1 gsm to 28 gsm. The membrane may have a mass per area of from 1 gsm to 27 gsm. The membrane may have a mass per area of from 1 gsm to 26 gsm. The membrane may have a mass per area of from 1 gsm to 25 gsm.

[0097] The membrane may have a maximum pore size of less than 5 pm. The membrane may have a maximum pore size of less than 4 pm. The membrane may have a maximum pore size of less than 3 pm. The membrane may have a maximum pore size of less than 2.5 pm. The membrane may have a maximum pore size of less than 2 pm. The membrane may have a maximum pore size of less than 1.5 pm. The membrane may have a maximum pore size of less than 1.25 pm.

[0098] The membrane may have a maximum pore size from 0.05 to 5 pm. The membrane may have a maximum pore size from 0.05 to 4 pm. The membrane may have a maximum pore size from 0.05 to 3 pm. The membrane may have a maximum pore size from 0.05 to 2.5 pm. The membrane may have a maximum pore size from 0.05 to 2 pm. The membrane may have a maximum pore size from 0.05 to 1.5 pm. The membrane may have a maximum pore size from 0.05 to 1.25 pm. The membrane may have a maximum pore size from 0.1 to 5 pm. The article may have a maximum pore size from 0.2 to 5 pm. The membrane may have a maximum pore size from 0.3 to 5 pm. The membrane may have a maximum pore size from 0.4 to 5 pm. The membrane may have a maximum pore size from 0.5 to 5 pm. The membrane may have a maximum pore size from 0.6 to 5 pm. The membrane may have a maximum pore size from 0.7 to 5 pm. The membrane may have a maximum pore size from 0.8 to 5 pm. The membrane may have a maximum pore size from 0.1 to 3 pm. The membrane may have a maximum pore size from 0.2 to 3 pm. The membrane may have a maximum pore size from 0.3 to 3 pm. The membrane may have a maximum pore size from 0.4 to 3 pm. The membrane may have a maximum pore size from 0.5 to 3 pm. The membrane may have a maximum pore size from 0.6 to 3 pm. The membrane may have a maximum pore size from 0.7 to 3 pm. The membrane may have a maximum pore size from 0.8 to 3 pm.

[0099] The membrane may have a porosity of at least 10%. The membrane may have a porosity of at least 20%. The membrane may have a porosity of at least 30%. The membrane may have a porosity of from 10% to 90%. The membrane may have a porosity of from 10% to 80%. The membrane may have a porosity of from 10% to 70%. The membrane may have a porosity of from 10% to 60%. The membrane may have a porosity of from 10% to 50%. The membrane may have a porosity of from 20% to 50%. The membrane may have a porosity of from 30% to 50%. The membrane may have a porosity of from 10% to 40%.

[0100] The membrane may have a thickness of less than or equal to 100 pm. The membrane may have a thickness of less than or equal to 75 pm. The membrane may have a thickness of less than or equal to 50 pm. The membrane may have a thickness of less than or equal to 45 pm. The membrane may have a thickness of less than or equal to 40 pm. The membrane may have a thickness of less than or equal to 35 pm. The membrane may have a thickness of less than or equal to 30 pm.

[0101] The membrane may have a thickness of from 1 pm to 100 pm. The membrane may have a thickness of from 1 pm to 75 pm. The membrane may have a thickness of from 1 pm to 50 pm. The membrane may have a thickness of from 5 pm to 50 pm. The membrane may have a thickness of from 5 pm to 45 pm. The membrane may have a thickness of from 5 pm to 40 pm. The membrane may have a thickness of from 5 pm to 35 pm. The membrane may have a thickness of from 5 pm to 30 pm. The membrane may have a thickness of from 10 pm to 50 pm.

[0102] The membrane may be stable at high temperatures. The membrane may be stable at temperatures up to 300°C. The membrane may be stable at temperatures up to 280°C. The membrane may be stable at temperatures up to 260°C. The membrane may have a reduction in airflow through the article of less than 15% after exposure to high temperatures. The membrane may have a reduction in airflow through the article of less than 15% after exposure to 260°C. The membrane may have a reduction in airflow through the article of less than 10% after exposure to 260°C.

[0103] The membrane may have a reduction in airflow through the article of less than 0.5 L / hr after exposure to 260°C. The membrane may have a reduction in airflow through the article of less than 0.4 L / hr after exposure to 260°C. The membrane may have a reduction in airflow through the article of less than 0.3 L / hr after exposure to 260°C. The membrane may have a reduction in airflow through the article of less than 0.2 L / hr after exposure to 260°C. The membrane may have a reduction in airflow through the article of less than 0.1 L / hr after exposure to 260°C.

[0104] The vent assembly may have a water entry pressure of at least 0.10 bar. The vent assembly has water entry pressure of at least 0.15 bar. The vent assembly has water entry pressure of from 0.10 bar to 1.0 bar. The vent assembly has water entry pressure of from 0.15 bar to 1.0 bar.

[0105] The vent assembly may have an airflow of at least 0.5 L / hr as measured at 12 mbar. The vent assembly may have an airflow of at least 1.0 L / hr as measured at 12 mbar. The vent assembly may have an airflow of at least 1.5 L / hr as measured at 12 mbar. The vent assembly may have an airflow of at least 2.0 L / hr as measured at 12 mbar. The vent assembly may have an airflow of at least 2.25 L / hr as measured at 12 mbar. The vent assembly may have an airflow of at least 2.5 L / hr as measured at 12 mbar. The vent assembly may have an airflow of at least 2.75 L / hr as measured at 12 mbar. The vent assembly may have an airflow of from 0.5 L / hr to 10 L / hr. The vent assembly may have an airflow of from 1.0 L / hr to 10 L / hr. The vent assembly may have an airflow of from 1.5 L / hr to 10 L / hr. The vent assembly may have an airflow of from 2.0 L / hr to 10 L / hr. Airflow of the vent assembly is as measured using the method provided below.

[0106] The vent assembly may be an acoustic vent. Accordingly, the vent assembly may be configured to prevent the passage of liquids and / or particulates through the vent assembly whilst minimising the impact of the vent assembly on the transmission of sound through the vent assembly.

[0107] The vent assembly may have an insertion loss of less than 2.5 dB measured at 1 kHz. The vent assembly may have an insertion loss of less than 2.0 dB measured at 1 kHz. The vent assembly may have an insertion loss of less than 1.5 dB measured at 1 kHz. The vent assembly may have an insertion loss of from 0.1 dB to 3.0 dB measured at 1 kHz. The vent assembly may have an insertion loss of from 0.1 dB to 2.5 dB measured at 1 kHz. The vent assembly may have an insertion loss of from 0.1 dB to 2.0 dB measured at 1 kHz. The vent assembly may have an insertion loss of from 0.1 dB to 1.5 dB measured at 1 kHz.

[0108] The vent assembly may have a bubble point of at least 0.2 bar. The vent assembly has a bubble point of at least 0.25 bar. The vent assembly may have a bubble point of at least 0.3 bar. The vent assembly may have a bubble point of at least 0.4 bar. The vent assembly may have a bubble point of at least 0.5 bar. The vent assembly may have a bubble point of at least 0.6 bar.

[0109] The vent assembly may have a bubble point of from 0.2 bar to 3 bar. The vent assembly may have a bubble point of from 0.3 bar to 3 bar. The vent assembly may have a bubble point of from 0.4 bar to 3 bar. The vent assembly may have a bubble point of from 0.5 bar to 3 bar. The vent assembly may have a bubble point of from 0.6 bar to 3 bar. The vent assembly may have a bubble point of from 0.2 bar to 2.5 bar. The vent assembly may have a bubble point of from 0.2 bar to 2 bar. The vent assembly may have a bubble point of from 0.2 bar to 1.5 bar.

[0110] The vent assembly may comprise a support layer. The membrane may be provided on the support layer such that the support layer provides mechanical support to the membrane. The membrane may be arranged adjacent to the support layer. For example, a support adhesive layer may be provided between the membrane and support layer. The membrane may contact the support layer. The membrane may be fixed to the support layer. The membrane may be fixed to the support layer my welding or similar. An adhesive layer of the at least one adhesive layer may be provided on the membrane on a side of the membrane opposed to the side of the membrane adjacent to or contacting the support layer.

[0111] According to a fifth aspect there is provided a device comprising the vent assembly of the fourth aspect.

[0112] The device may be an electronic device. The device may comprise a housing defining an aperture, and the vent assembly occludes the aperture. The vent assembly may prevent the ingress of liquids or particulates through the aperture into the interior of the housing.

[0113] The device may further comprise an acoustic transducer positioned adjacent to the aperture. The device may be a battery device. The battery device may be a pouch battery cell. The battery device may be a prismatic can battery cell. The vent assembly may be configured to allow egress of gas that may be formed during use of the battery device. For example, electrolyte held or retained within the battery device may decompose or degrade to form gas within the battery device during use. The vent assembly may be configured to prevent or substantially prevent the ingress of water into the battery device.

[0114] In a sixth aspect there is provided a device comprising the article of the first aspect or the article made by the method of the second aspect.

[0115] The device may be an electronic device. The device may be a battery device.

[0116] Brief Description of the Figures

[0117] Embodiments of the present invention will now be described, by way of non-limiting example, with reference to the accompanying drawings.

[0118] Figure 1: A schematic illustration of the electrospinning process;

[0119] Figure 2: A schematic side view of a mat of nanofibers after electrospinning (A), after fusing (B), and after curing (C);

[0120] Figure 3: A schematic side view of a vent assembly according to an embodiment;

[0121] Figure 4: A schematic top down view of a vent assembly according to an embodiment mounted onto a support plate;

[0122] Figure 5: A SEM of the top surface of a mat of nanofibers according to an embodiment; Figure 6: A SEM of the bottom surface of a mat of nanofibers according to an embodiment; and

[0123] Figure 7: A SEM of a cross section of a mat of nanofibers according to an embodiment.

[0124] Detailed Description

[0125] While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.

[0126] To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as "a", "an" and "the" are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as outlined in the claims.

[0127] Test Methods

[0128] Thickness measurement:

[0129] A Heidenhain MT 60M thickness measurement sensor was used. The contact area was a circular sensor tip with a base area of 0.785 cm2. The sample was laid flat on the base plate of the measurement device and all wrinkles were gently removed. Then the sensor tip was moved towards the sample with a force of 1 N. The thickness of the sample was measured.

[0130] Areal weight determination:

[0131] An Ohaus explorer precision scale was used to determine the weight of a 0.03 m diameter disk (A = 0.000706 mm2).

[0132] The measured areal weight was multiplied by 1 / 0.000706 to “gram per square meter" unit.

[0133] Porosity evaluation:

[0134] The porosity was calculated using the following formula:

[0135] Porosity = 100*(1 - (density bulk silicone rubber 1.11 g / cm3 / density of sample))

[0136] Whereas the density of the sample was calculated by following formula:

[0137] sample areal weight / sample thickness

[0138] Airflow measurement:

[0139] An ATEQ D520 instrument was used to determine air permeability of the samples. The sample was put between two plates with a hole having an area of 2.99 cm2and a pressure of 12 mbar was used to determine the airflow of a sample at that constant pressure.

[0140] Viscosity measurement:

[0141] A Brookfield Metek DV2T Viscosimeter (Model: DX2TRVKB0) was used to determine the viscosity of the polymer solvent mixtures. The polymer solvent mixtures were analyzed with different spindle geometries depending on the viscosity range of the fluid. The viscosity was measured at 100RPM.

[0142] Electrical conductivity analysis:

[0143] A Mettler Toledo Seven2Go Conductivity Messgerat S3-Meter with an Mettler Toledo inlab® 720 electrical conductivity sensor (0.1 to 500 µS / cm) was used to measure electrical conductivity of the polymer solvent mixtures.

[0144] Bubble Point and Pore Size analysis:

[0145] The bubble point was measured according to the general teachings of ASTM F316-03 using a Capillary Flow Porometer (Model 3G zh from Quantachrome Instruments) using a built-in automated method. The sample holder comprised a porous metal plate (Part Number: 04150-10030-25, Quantachrome Instruments) 25.4 mm in diameter and a PVDF mesh with 150 micron openings and 100 micron fiber diameter. The sample was placed above the metal plate and the PVDF mesh material. The sample was then clamped down and sealed using an O-ring (Part Number: 51000-25002000, Quantachrome Instruments). The sample was wet with a silicone fluid (Porewet Porometer wetting fluid, purchased from 3P instruments GmbH & Co. KG) having a surface tension of 16.0 dynes / cm prior to running the test.

[0146] The max. Pore size was calculated with following formula:

[0147]

[0148] where:

[0149] P = bubble-point pressure

[0150] g = surface tension of the liquid, q = liquid-solid contact angle, D = diameter of the pore

[0151] SEM Analysis:

[0152] A Gemini SEM 500 was used to create SEM pictures from the samples.

[0153] Fiber Diameter Analysis:

[0154] 1024x768 pixel SEM pictures with a magnification of 2000x was used as input for the software. Digital Surf MountainsSEM Color Software with fiber analysis module (light fibers on dark background) was used to determine the average fiber diameter of the samples. Defects such as beads or other not fibrous structures were excluded from the fiber analysis. Vent Assembly Level (or Performance) Test Methods

[0155] Preparation and performance testing of the Embodiment vent assemblies of the present disclosure as well as preparation and performance testing of the comparative vent assemblies will be described herein below.

[0156] The Performance Test Methods for testing performance of the vent assemblies in a number of embodiments are as follows:

[0157] Sample Preparation

[0158] With reference to Figure 3, a vent assembly (20) comprises a membrane (22), a first adhesive layer (24) a first support (26) (acting as a support layer), a second adhesive layer (28) and a second support layer (30). The first adhesive layer (24) and the second adhesive layer (28) defines a central aperture (32) having an internal diameter of 1.5 mm and the membrane (22) is exposed through the central aperture (32).

[0159] The membrane (22) comprises a mat of nanofibers (corresponding to a plurality of nanofibers). The mat of nanofibers comprises a copolymer of PDMS and PMVS and PMMA (acting as a secondary polymer). The amount of PMMA was 5% by weight.

[0160] The first support layer (26) and the second support layer (30) was a polyimide coupon having a thickness of 250 pm. The first adhesive layer (24) and the second adhesive layer (28) comprises a polyimide substrate (34) with a silicone adhesive layer (36) on either side of the polyimide substrate (34).

[0161] With reference to Figure 4, a support plate (40) comprises an aperture (42) and a sample vent according to an embodiment is mounted to the support plate (40) such that the membrane (44) of the vent assembly is exposed through the aperture (42) in the support plate (40). The support plate (40) also comprises a pair of locating apertures (46, 48) that allow the support plate (40) to be mounted to a testing rig. The support plate mounted examples were then tested to determine airflow, insertion loss prior to and post reflow conditions.

[0162] Vent assembly samples were prepared in a reflow-compatible coupon comprising polyimide (monolithic 10 mil in sheet form) and silicone pressure sensitive adhesive (PSA) (Double sided silicone adhesive with polyimide center carrier, 2 mil total in roll form, Flexcon, part number SA6102-LR) to evaluate performance in application. The coupon consisted of the following layers: (Layer 1) Polyimide, (Layer 2) Silicone PSA, (Layer 3) Membrane Sample, (Layer 4) Polyimide, (Layer 5) Silicone PSA. The polyimide coupon and adhesive layers include 1,5mm inner diameter holes, which are aligned in the stack-up, leaving an exposed membrane region representative of the active area of a venting assembly.

[0163] Three coupons were prepared for each vent assembly composition comprising a polyimide membrane and the coupons were tested for transmission loss and vent assembly level airflow before and after the reflow process. We refer to Figures 3 and 4 of the drawings showing the assembly used for the sample preparation and testing performance of the embodiments of the present disclosure and the Comparative Examples described herein below.

[0164] SPL Acoustic Response (Insertion Loss determination)

[0165] dB SPL acoustic response measurement involves detecting an acoustic test signal after it passes through the acoustic vent.

[0166] The acoustic response of our samples, measured in terms of dB SPL, was measured using a MEMS microphone fixture placed inside a Bruel & Kjaer 4232 anechoic box at a distance of 6.5 cm from an internal speaker. SoundCheck 5.0 software and AmpConnect hardware (both acquired commercially from Listen Inc) were used to record the output response curve. An SCM-3 reference microphone (Listen Inc.) and calibrator (Bruel & Kjaer) were used to generate a calibration sequence prior to measuring the sample. A sample fixture was designed to accept the sample coupon which holds the sample to be tested. The speaker performs a frequency sweep at 94 dB sound pressure level over a frequency range from 100 Hz to 10 kHz. The measurement microphones measure the acoustic response as a sound pressure level in dB over the frequency range. In general, the dB SPL value can be compared against a predetermined baseline signal measured at the same 94dB reference level without sample present or to another sample that was prepared at a different angle or aspect ratio. A larger dB SPL value at a given frequency corresponds to better acoustic performance.

[0167] Vent Assembly Level Airflow (ATEQ)

[0168] The airflow test described previously measures laminar volumetric flow rates of air through membrane samples, but it can be adapted to measure airflow rates through vent assemblies as described herein. An ATEQ® (ATEQ Corp., Livonia, Ml) D250 Flowmeter was used to measure vent assembly level airflow rate (L / hr) through the 1.5mm membrane area in each sample coupon ID by challenging it with a differential air pressure of 1.2 kPa (12 mbar) using an aluminum fixture. The Flowmeter Test connection (air outlet) was routed to the fixture with 3 / 8” flexible tubing. Each coupon was centered to align the coupon ID to direct airflow through the membrane area of the coupon, and the surface of the coupon was sealed to the air outlet with an O-ring under compression. Three coupons were measured before and after reflow for each membrane.

[0169] The airflow delta is the percent change in airflow due to reflow, calculated with the following equation:

[0170] * ■■ 11 r\ ii itw | Airflow

[0171]

[0172] rt.f iw Airflowprereflow I

[0173] Airflow Delta = 100 o ■- — — — — — —

[0174] Airflowpp,relluw

[0175] The delta airflow calculation as described is always greater than zero.

[0176] Water entry pressure (WEP) test

[0177] The water entry pressure (WEP) test is applied to a vent assembly and the vent assembly is clamped and sealed in a sample holder. Water pressure is applied to one side (having the first membrane) and the pressure was ramped up in small increments (0.03 psi / s) from 0-90 psi over a period of 50 minutes. If water does not intrude through the vent assembly to be visible on the opposite side during the specified duration, the sample is deemed to have passed the WEP test. After the test duration, the sample can be disassembled and it can be determined whether water has passed through each membrane or none of the above.

[0178] Reflow

[0179] Reflow is a soldering process used in electronics manufacturing to form a strong electrical and mechanical solder bond between a MEMS device and a circuit board. This is generally achieved by placing parts in a reflow oven that exposes the electronics components through a rapid thermal cycle and in some instances, MEMS components may go through several reflow cycles. In MEMS application, performance of the devices must be maintained after the reflow process. In general, reflow cycles reach temperatures up to approximately 260-280 °C.

[0180] The sample coupons were passed through a single reflow cycle in a 5-zone convection reflow oven Model HTC-125 (commercially available by DDM Novastar Inc). The recipe on the reflow oven (zone temperatures and conveyor belt speed) was optimized using a Model K2 Profile Setter (commercially available by KIC Thermal), which converged on a process to expose the sample to the target thermal profile outlined below.

[0181] Target thermal profile:

[0182] Ramp-up (217°C to Peak Temperature): 0 to 3°C per second

[0183] Ramp-down (Peak Temperature to 200°C): -3 to 0°C per second Ramp (200°C to Peak Temperature): 0 to 3°C per second

[0184] Soak time (150 to 200°C): 60 to 180 seconds

[0185] Reflow time (time above 217°C): 60 to 150 seconds

[0186] Peak Temperature: 255 to 260°C

[0187] Time within 5°C of peak: 30 to 40 seconds

[0188] Time from ambient (25°C) to Peak: 0 to 8 minutes

[0189] The profile was optimized based on measurements of temperature measured by thermocouples placed at the center coupon inner diameter to ensure that the membrane active area is exposed to the desired reflow profile. Acoustic transmission loss and vent assembly level airflow performance were measured before and after this reflow process.

[0190] Materials

[0191] PDMS / PMMA Article (Examples 1-5)

[0192] 1 ) A polymer was mixed with a solvent to create a polymer / solvent system.

[0193] A silicone system (“A1”) consisting of an “A” and “B” component was purchased from KauPo Plankenhorn e. K. (Carl-Benz-Str. 4 in 78549 Spaichingen, Germany). This mix consists of a high molecular weight copolymer of dimethylsiloxane and methylvinylsiloxane, fumed silica particles and a platinum cross-linking agent. The article number was CSG-65 (A+B).

[0194] PMMA having an average molecule weight of 960,000 g / mol (“PMMA1”) was purchased from Sigma Aldrich. To create the polymer solvent mix the PMMA was mixed with methylethyl ketone (MEK).

[0195] After full dissolution (24h) of the PMMA1 the PDMS silicone system was added to the mix until fully solvated (24h) to form a PDMS spinning solution.

[0196] PDMS / Secondary Polymer Article (Examples 6-24)

[0197] A silicone system (“A2”) consisting of an “A” and “B” component was purchased from Zaklad Chemiczny „Silikony Polskie” Sp. z o.o. 37-310 Nowa Sarzyna, ul. Chemikow 1, woj. Podkarpackie. This mix consists of a high molecular weight copolymer of dimethylsiloxane and methylvinylsiloxane, 30% fumed silica particles (Examples 17-24) or 35% fumed silica particles (Examples 6-16) and a peroxide cross-linking agent. The article number was MV 1.0. An additive selected from the group below were purchased from Sigma Aldrich. To create the polymer solvent mix one of the additives was mixed with MEK.

[0198] Additives:

[0199] PMMA having an average molecular weight of 350,000 g / mol (“PMMA2”).

[0200] Polystyrene having an average molecular weight of 350,000 g / mol (“PS”).

[0201] High molecular weight polyvinyl chloride (“PVC”).

[0202] After full dissolution (24h) of the additive the PDMS silicone system was added to the mix until fully solvated (24h) to form a PDMS spinning solution.

[0203] Figure 1 shows a schematic general illustration of an electrospinning method (1) of producing nanofibers. A polymer / solvent mix (2) (acting as a precursor solution) is retained within a syringe and slowly pumped with a constant rate through a needle with a defined inner diameter. At the needle tip (4) the polymer / solvent mix (2) is charged and the difference in charge between the mix (2) at the needle tip (4) and a grounded collector (6) draws the polymer / solvent mix (2) towards the collector (6) where it forms fine nanofibers that build up to form a nanofiber membrane (8). As the mix (2) travels from the needle tip (4) to the collector (6) solvent evaporates from the mix such that a substantially dry nanofiber is deposited on the collector (6).

[0204] Figure 2 shows a series of schematic side views of a nanofiber mat (10) after it is initially spun onto a collector (12) (A), after the nanofibers (14) of the nanofiber mat (10) have fused together (B), and after the fused nanofibers (16) have been cured (C).

[0205] In the current example, the PDMS spinning solution was spun with a single nozzle electrospinning machine (“Starter Kit”) obtained from Inovenso, in which high voltage was applied to direct the jet towards the other electrode at high speed where a collector is used to collect the fibers which are formed due to the forces on the electrospinning solution. The spun mat was heat treated to obtain a cured nonwoven material that contains nanofibers.

[0206] In particular, an electrospun nanofiber membrane was made using a single needle electrospinning device and a static aluminium drum (80 mm diameter) collector with feeding the polymer / solvent system through a small diameter needle that is connected to a high voltage generator. The strong electric field is stretching the polymer / solvent system to form a fine nanofiber. The created nanofibers were collected on a “substrate” that was wrapped around the aluminium drum, so that after creation of a nanofiber nonwoven membrane the “removable processing carrier can be peeled off the nanofiber nonwoven membrane to obtain a “standalone nanofiber membrane”. Those “removable processing carrier” need to avoid an unwanted strong adhesion of the nanofibers so that they are fully removable.

[0207] Example 1 was created using a 0.97mm inner diameter needle, a distance form the needle tip to collector of 100mm, 13kV positive voltage on needle and a grounded metal collector electrode, an antistatic PTFE / glassfiber woven substrate and 15 minutes spinning time. The environmental conditions where approximately 22°C and 50% humidity.

[0208] Example 2 was made using the process for Example 1 above with a 30min spinning time.

[0209] Example 3, 4 and 5 were made using the process of Example 1 above with a 30kV positive voltage on the needle. Example 4 used a Nylon Nonwoven substrate (obtained from Cerex Advanced Fabrics, Inc. under part number “Cerex Type 23200”).

[0210] Examples 6 to 24 were made using the process of Example 1 above with a 40 minute spinning time.

[0211] Curing:

[0212] The nanofiber membrane on the substrate was cured in an oven at a temperature of 155°C to obtain a cured silicone rubber nanofiber membrane.

[0213] An example SEM of a topside (adjacent to the electrospinning spinning needle) and a bottom side (adjacent to the collector) are shown in Figure 5 and 6 respectively. The example comprises nanofibers made of the silicone A1 and PMMA (960k average molecular weight) in a 20:1 ratio and had a fiber diameter of 643 nm, a mass per area of 15.7 g / m2, a thickness of 18 pm. The measured bubble point was 0.68 bar, the airflow at 12 mbar was 67.2 L / h and an elongation at maximum force of 233%. The process details to make the sample were as followed: Following the procedure as above for Example 1 but using a rotating and translating collector. The precursor solution was made up to 10% polymer in MEK, with 44 cP viscosity, and 22 pS / cm electrical conductivity. The precursor solution was spun with a spinning time of 60 minutes with an applied 25kV positive voltage on needle, and the collector was rotated at 35RPM and translated side to side by 50 mm at a rate of 3s / 50mm. Figure 7 shows a side cross-section of the example article on a collector substrate.

[0214] Examples 1-24 were made using the above general method varying the thickness and mass per area of the membranes and the properties of these Examples is shown in table 1 below.

[0215]

[0216] Table 1: Example nanofiber articles and their composition and properties

[0217]

[0218] Table 2: Further properties of example nanofiber articles

[0219] Examples 25 and 26 are comparative examples as described in Moghadas et al. (Biomed Microdevices (2017) 19:74) and comprises (“Sylgard 184” obtained from Dow, USA) A2 with 50% PMMA (Example 25) and 14% PMMA (Example 26).

[0220]

[0221] Table 3: Comparative articles and their compositions and properties

[0222] As can been seen examples 1-5 have a significantly reduced mean fiber diameter and have a significantly reduced maximum pore size and porosity when compared to the comparative examples 25 - 26. In addition, examples 25 and 26 would indicate to the person skilled in the art that reducing the proportion of PMMA would increase the diameter of the fibers, whilst in contrast examples 1 -5 show that using 5% PMMA with HMW silicone produces very fine fibers that have a mean diameter of significantly less than 1 micron.

[0223] In addition, the articles of examples 1-5 have significantly improved elasticity as indicated by their elongation at maximum force when compared to comparative examples 25 and 26. As a result, the articles of examples 1-5 are much more flexible and much less likely to fracture or fail.

[0224] Temperature Stability

[0225] The effect of exposure to a temperature of 260°C was tested for the article of Example 1 and the results are shown below in Table 4.

[0226]

[0227] Table 4: Acoustic performance of Example 1

[0228] As can be seen, the acoustic and airflow performance of the article of example 1 is largely not affected by exposure to heat. This is particularly notable for electronic device applications where the article is used in a vent assembly and may be applied before final soldering of components adjacent to the vent assembly.

[0229] While there has been hereinbefore described approved embodiments of the present invention, it will be readily apparent that many and various changes and modifications in form, design, structure and arrangement of parts may be made for other embodiments without departing from the invention and it will be understood that all such changes and modifications are contemplated as embodiments as a part of the present invention as defined in the appended claims.

Claims

Claims1. An article comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a silicone rubber and from 1% to 25% of a secondary polymer, wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 1 μm.

2. The article of claim 1, wherein the secondary polymer is selected from poly(methyl methacrylate) (PMMA), polystyrene (PS), or polyvinyl chloride.

3. The article of claim 1 or claim 2, wherein the nanofibers of the plurality of nanofibers comprise from 1 % to 10% of the secondary polymer.

4. The article of any preceding claim, wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 0.8 pm.

5. The article of preceding claim, wherein the article is a nonwoven article.

6. The article of any preceding claim, wherein the silicone rubber is a high molecular weight silicone rubber (HMWS rubber).

7. The article of claim 6, wherein the HMWS rubber has an average molecular weight of at least 100,000 g / mol.

8. The article of any preceding claim, wherein the silicone rubber comprises polydimethylsiloxane (PDMS), polymethylvinylsiloxane (PMVS), polymethylphenylsiloxane (PMPS), fluorosilicone rubber (FVMQ), functionalised PDMS, or copolymers thereof.

9. The article of claim 8, wherein the silicone rubber comprises PDMS.

10. The article of claim 8, wherein the silicone rubber comprises a copolymer of PDMS and PMVS.

11. The article of any preceding claim, wherein the article has a mass per area or less than 30 gsm.

12. The article of any preceding claim, wherein the article has a bubble point of at least 0.2 bar.

13. The article of any preceding claim, wherein the article has a bubble point of from 0.2 bar to 3 bar.

14. The article of any preceding claim, wherein the article has a maximum pore size of less than 3 pm.

15. The article of any preceding claim, wherein the article has a maximum pore size from 0.05 to 3 pm16. The article of any preceding claim, wherein the article has a thickness of less than 50 pm.

17. The article of any preceding claim, wherein the article has a thickness of from 5 pm to 50 pm.

18. The article of any preceding claim, wherein the nanofibers of the plurality of nanofibers comprise a filler material.

19. The article of claim 18, wherein the filler material comprises fumed silica.

20. The article of claim 18 or claim 19, wherein the nanofibers of the plurality of nanofibers comprise from 20% to 60% filler material by weight.

21. The article of any preceding claim, wherein the article has an elongation to break of at least 100%.

22. The article of any preceding claim, wherein the article has an elongation to break of from 100% to 500%.

23. The article of any preceding claim, wherein the article is a membrane.

24. The article of any preceding claim, wherein the article is formed using electrospinning.

25. A method of forming an article comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising a high molecular weight silicone rubber, the method comprising the steps:providing a high molecular weight silicone (HMWS) material;adding the HMWS material to a solvent to form a precursor solution; solution spinning the precursor solution to form a mat of nanofibers; andcuring the HMWS in the mat of nanofibers to HMWS rubber to form an article.

26. The method of claim 25, wherein the HMWS material has a viscosity of more than 20 cP when solvated in methyl ethyl ketone (MEK) at 20% polymer by weight.

27. The method of claim 26, wherein the HMWS material has a viscosity of more than 100 cP when solvated in MEK at 20% polymer by weight.

28. The method of any of claim 25 to claim 27, wherein the HMWS material has an average molecular weight of at least 100,000 g / mol.

29. The method of any of claim 25 or claim 28, wherein the HMWS material comprises at least 20% filler.

30. The method of claim 29, wherein the filler comprises fumed silica.

31. A vent comprising the article of any of claim 1 to claim 24 or the article formed by the method of any of claim 25 to claim 30.

32. A vent assembly comprising a membrane and at least one adhesive layer, the membrane comprising a plurality of nanofibers, the nanofibers of the plurality of nanofibers comprising silicone rubber.

33. The vent assembly of claim 32, wherein the vent assembly has water entry pressure of at least 0.15 bar.

34. The vent assembly of claim 32 or claim 33, wherein the vent assembly has an airflow of at least 0.5 L / hr as measured at 12 mbar.

35. The vent assembly of any of claim 32 to claim 34, wherein the vent assembly is an acoustic vent.

36. The vent assembly of claim 35, wherein the vent assembly has an insertion loss of less than 2.5 dB measured at 1 kHz.

37. The vent assembly of any of claim 32 to claim 36, wherein the nanofibers of the plurality of nanofibers comprise 1% to 25% of a secondary polymer.

38. The vent assembly of claim 37, wherein the secondary polymer is a thermoplastic polymer.

39. The vent assembly of claim 38, wherein the secondary polymer comprise polyurethane, polyamide, polylactic acid, polycarbonate, polyether sulfone, polyether ether ketone (PEEK), polyetherimide (PEI), polyethylene, polypropylene, polyphenylene sulfide (PPS), polyacrylate, polyethylene glycol (PEG), polyvinylacetate (PVA) acrylonitril butadien stytrene (ABS), polyvinyl chloride (PVC) or polystyrene.

40. The vent assembly of any of claim 32 to claim 39, wherein the silicone rubber comprises high molecular weight silicone (HMWS).

41. The vent assembly of any of claim 32 to claim 40, wherein the silicone rubber comprises polydimethylsiloxane (PDMS), functionalised PDMS, polymethylvinylsiloxane (PMVS), polymethylphenylsiloxane (PMPS) or fluorosilicone rubber (FVMQ) or copolymers thereof.

42. The vent assembly of claim 41, wherein the silicone rubber comprises PDMS or a functionalised form thereof.

43. The vent assembly of claim 41, wherein the silicone rubber comprises a copolymer of PDMS and PMVS.

44. The vent assembly of any of claim 32 to claim 43, wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 1 μm.

45. The vent assembly of claim 44, wherein the nanofibers of the plurality of nanofibers have a mean diameter of less than 0.8 pm.

46. The vent assembly of any of claim 32 to claim 45, wherein the vent assembly has a bubble point of at least 0.25 bar.

47. The vent assembly of claim 46, wherein the vent assembly has a bubble point of at least 0.5 bar.

48. A device comprising the vent assembly of any of claim 32 to claim 47.

49. The device of claim 48, wherein the device comprises a housing defining an aperture, and the vent assembly occludes the aperture.

50. The device of claim 49 further comprising an acoustic transducer positioned adjacent to the aperture.

51. A device comprising the article of any of claim 1 to claim 24 or the article made by the method of any of claim 25 to claim 30.

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