Hydrophobic breathable film and preparation method thereof

Abstract

The invention belongs to the field of membrane materials, and particularly relates to a hydrophobic breathable membrane and a preparation method thereof. The hydrophobic gas-permeable membrane provided by the invention is prepared by sequentially performing plasma bombardment activation, chemical vapor deposition of a SiO2 nano layer, hydrothermal synthesis of a CuSiO3 nano needle-shaped structure and modification of a hydrophobic silane coupling agent on the surface of a PTFE porous membrane. The method comprises the following steps: firstly, activating the surface of the PTFE membrane by utilizing a plasma bombardment technology to enable the PTFE membrane to have modifiability; then covering the surface of the activated film structure with a nano-scale SiO2 thin layer by means of a chemical vapor deposition (CVD) technology, so that the CuSiO3 nano needle-shaped structure can be constructed at one time through a hydrothermal synthesis method; finally, a hydrophobic silane coupling agent is modified, so that the membrane material has strong hydrophobicity. Experimental results show that the water contact angle of the hydrophobic breathable membrane is larger than 140 degrees, and the breathability is reduced by less than 5% compared with that of a PTFE porous membrane before treatment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of membrane materials, and particularly relates to a hydrophobic and air-permeable membrane and a preparation method thereof. BACKGROUND

[0002] Membrane-based liquid-membrane boiling phase change cooling technology is a high-efficiency phase change cooling technology using a porous hydrophobic membrane as a separation medium and realizing forced gas-liquid separation by using the pressure drop on both sides of the membrane as the driving force. The porous hydrophobic membrane used must have high hydrophobicity, high air permeability and high thermal and mechanical stability. Commercial porous hydrophobic membranes are mainly made of polypropylene (PP), polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) materials. PP and PVDF have poor thermal stability and insufficient hydrophobicity.

[0003] PTFE porous membranes have excellent thermal stability, their pore size can be adjusted in the range of 0.2-5 µm, and they are commercially mature and low in cost. However, the limited hydrophobicity of the PTFE membrane restricts its application in the membrane-based liquid-membrane boiling phase change cooling technology. The low surface energy and poor adhesion of the PTFE membrane make it difficult to combine the surface of the PTFE membrane with other strongly hydrophobic materials, hindering the strengthening of the hydrophobicity. Some researchers have adopted the methods of dip coating and pressure filtration to composite fluorinated nano-silicon dioxide particles with PTFE commercial membranes, improving the hydrophobicity of the PTFE membrane. However, due to the surface chemical inertness of PTFE, the bonding force between the fluorinated nano-silicon dioxide particles and PTFE is weak, and the stability of the micro-nano structure prepared on the surface of the PTFE membrane by dip coating is poor. After several uses or under the conditions of high-speed fluid scouring, the micro-nano structure is easy to fall off, resulting in a rapid decrease in the hydrophobicity of the membrane, which cannot meet the demand for long-term stable use. Moreover, the filling of nano-particles will greatly reduce the air permeability of the membrane, and seriously reduce the exhaust rate during boiling phase change cooling. In addition, some researchers have adopted atomic layer deposition technology to deposit nano-structures on the surface of the PTFE membrane to regulate its hydrophobicity. However, this method requires tens or even hundreds of deposition operations, which is not only time-consuming but also expensive, and requires specific operation equipment. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a hydrophobic and air-permeable membrane and a preparation method thereof. The present application can conveniently and low-costly construct a hydrophobic nano-structure on the surface of a PTFE porous membrane while maintaining the high air permeability of the PTFE porous membrane, and strengthen the hydrophobicity thereof.

[0005] The present application provides a hydrophobic and air-permeable membrane, which is made of a PTFE porous membrane whose surface is sequentially activated by plasma bombardment, deposited with a SiO2 nano-layer by chemical vapor deposition, hydrothermally synthesized with CuSiO3 nano-needle-like structures and modified with a hydrophobic silane coupling agent.

[0006] The application provides a preparation method of the hydrophobic and breathable film.

[0007] a) performing plasma bombardment on the surface of the PTFE porous film to obtain a surface-activated PTFE film;

[0008] b) depositing a SiO2 nano layer on the surface of the surface-activated PTFE film by using a chemical vapor deposition method;

[0009] c) growing CuSiO3 nano needle-like structures on the SiO2 nano layer by using a hydrothermal synthesis method;

[0010] d) modifying the CuSiO3 nano needle-like structures by using a hydrophobic silane coupling agent to obtain the hydrophobic and breathable film.

[0011] Preferably, in step a), the plasma bombardment is performed in an air or pure oxygen atmosphere; the air pressure of the plasma bombardment is 10-30 Pa; the gas flow of the plasma bombardment is 200-600 sccm; the power of the plasma bombardment is 200-600 W; and the time of the plasma bombardment is 2-5 min.

[0012] Preferably, in step b), the deposition process specifically comprises the following steps: under normal pressure, a SiO2 nano layer is deposited on the surface of the surface-activated PTFE film by using an ammonia-catalyzed tetraethyl orthosilicate hydrolysis condensation method.

[0013] Preferably, in step b), the deposition time is 8-24 h.

[0014] Preferably, in step b), the thickness of the SiO2 nano layer is ≤100 nm.

[0015] Preferably, in step c), the process of growing the CuSiO3 nano needle-like structures specifically comprises the following steps: the PTFE film treated in step b) is mixed with a copper source solution, and hydrothermal synthesis is performed under a closed condition, so that the CuSiO3 nano needle-like structures are grown on the SiO2 nano layer of the PTFE film.

[0016] Preferably, in step c), the copper source solution contains copper acetate, ammonium chloride and ammonia water; the temperature of the hydrothermal synthesis is 90-140 ℃; and the time of the hydrothermal synthesis is 8-12 h.

[0017] Preferably, in step d), the hydrophobic silane coupling agent is 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane.

[0018] Preferably, in step d), the modification is performed under vacuum; the modification temperature is 70-90 ℃; and the modification time is 1-4 h.

[0019] Compared with the prior art, the application provides a hydrophobic and breathable film and a preparation method thereof. The hydrophobic and breathable film is prepared by sequentially performing the following steps on the surface of a PTFE porous film: plasma bombardment activation, chemical vapor deposition of a SiO2 nanolayer, hydrothermal synthesis of CuSiO3 nanoneedle structure, and modification with a hydrophobic silane coupling agent. The application first activates the surface of the PTFE film by using plasma bombardment technology, so that the surface has modifiability; then a nanoscale SiO2 thin layer is covered on the surface of the activated film structure by using chemical vapor deposition (CVD) technology, so that the CuSiO3 nanoneedle structure can be constructed by using the hydrothermal synthesis method; finally, the film material is made to have strong hydrophobicity by modifying the hydrophobic silane coupling agent. The experimental results show that the water contact angle of the hydrophobic and breathable film is >140°, and the air permeability is reduced by <5% compared with that of the PTFE porous film before treatment. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0021] Figure 1 is a preparation flowchart of the hydrophobic and breathable film provided by the application;

[0022] Figure 2 is a real photo of the untreated PTFE porous film provided by the application embodiment 1;

[0023] Figure 3 is a real photo of the PTFE hydrophobic and breathable film provided by the application embodiment 1;

[0024] Figure 4 is a water contact angle test result graph of the PTFE hydrophobic and breathable film provided by the application embodiment 1;

[0025] Figure 5 is a SEM graph of the film material provided by the application embodiment 1, wherein the upper left graph is a SEM graph of the untreated PTFE porous film (magnification ×10k), the upper right graph is a SEM graph of the PTFE hydrophobic and breathable film (magnification ×10k), the lower left graph is a SEM graph of the PTFE hydrophobic and breathable film (magnification ×50k), and the lower right graph is a SEM graph of the PTFE hydrophobic and breathable film (magnification ×100k). DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0027] The present application provides a kind of hydrophobic breathable film, by the surface of PTFE porous membrane sequentially through plasma bombardment activation, chemical vapor deposition SiO2 Nano layer, hydrothermal synthesis CuSiO3 Nanoneedle structure and hydrophobic silane coupling agent modification is made.

[0028] The present application also provides a kind of preparation method of hydrophobic breathable film, comprising the following steps:

[0029] a) the surface of PTFE porous membrane is bombarded by plasma, and surface-activated PTFE film is obtained;

[0030] b) using chemical vapor deposition method, SiO2 Nano layer is deposited on the surface of the surface-activated PTFE film;

[0031] c) using hydrothermal synthesis method, CuSiO3 Nanoneedle structure is grown on the SiO2 Nano layer;

[0032] d) the CuSiO3 Nanoneedle structure is modified by hydrophobic silane coupling agent, and hydrophobic breathable film is obtained.

[0033] In the preparation method provided by the present application, in step a), the pore size of the PTFE porous membrane is preferably 0.2-5 μm, and can be specifically 0.2 μm, 0.5 μm, 0.7 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm; the length of the pore channel of the PTFE porous membrane is preferably 8-12 μm, and can be specifically 8 μm, 8.2 μm, 8.5 μm, 8.7 μm, 9 μm, 9.2 μm, 9.5 μm, 9.7 μm, 10 μm, 10.2 μm, 10.5 μm, 10.7 μm, 11 μm, 11.2 μm, 11.5 μm, 11.7 μm or 12 μm; the porosity of the PTFE porous membrane is preferably 50-80%, and can be specifically 50%, 52%, 55%, 57%, 60 wt%, 62%, 65%, 67%, 70%, 72%, 75%, 77% or 80%; the water contact angle of the PTFE porous membrane is preferably 100-130°, and can be specifically 100°, 105°, 110°, 115°, 120°, 125° or 130°.

[0034] In the preparation method provided by the application, in step a), the plasma bombardment is preferably performed in an air or pure oxygen atmosphere; the gas pressure of the plasma bombardment is preferably 10-30 Pa, and can be specifically 10 Pa, 15 Pa, 20 Pa, 25 Pa or 30 Pa, and is most preferably 20 Pa; the gas flow of the plasma bombardment is preferably 200-600 sccm, and can be specifically 200 sccm, 300 sccm, 400 sccm, 500 sccm or 600 sccm, and is most preferably 400 sccm; the power of the plasma bombardment is preferably 200-600 W, and can be specifically 200 W, 300 W, 400 W, 500 W or 600 W, and is most preferably 400 W; and the time of the plasma bombardment is preferably 2-5 min, and can be specifically 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min or 5 min.

[0035] In the preparation method provided by the application, in step b), the deposition process preferably comprises: under normal pressure, using ammonia to catalyze the hydrolysis and condensation of tetraethyl orthosilicate to deposit a SiO2 nanolayer on the surface of the surface-activated PTFE film. The deposition time is preferably 8-24 h, and can be specifically 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h or 24 h; and the thickness of the SiO2 nanolayer is preferably ≤100 nm, and more preferably 70-100 nm, and can be specifically 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm or 100 nm.

[0036] In the preparation method provided by the application, in step c), the specific process of growing the CuSiO3 nanoneedle structure preferably comprises: mixing the PTFE film treated in step b) with a copper source solution, and performing hydrothermal synthesis under a sealed condition to grow the CuSiO3 nanoneedle structure on the SiO2 nanolayer of the PTFE film. The copper source solution preferably contains copper acetate, ammonium chloride and ammonia water, and the solvent is water. In the application, the ammonium chloride and ammonia water on one hand form NH3·H2O-NH4Cl buffer to provide a stable alkaline environment for the hydrothermal reaction; and on the other hand, NH3 provided by the ammonia water and Cl + provided by the ammonium chloride together act as ligands, and can be used to stabilize Cu - 2+ ​The mixed complex is formed to slow down the release rate and ensure uniform dispersion of the copper-based product. In the present application, the content of the copper acetate in the copper source solution is preferably 5-20 mmol / L, and specifically can be 5 mmol / L, 7 mmol / L, 10 mmol / L, 12 mmol / L, 15 mmol / L, 17 mmol / L or 20 mmol / L; the content of the ammonium chloride in the copper source solution is preferably 10-30 mmol / L, and specifically can be 10 mmol / L, 12 mmol / L, 15 mmol / L, 17 mmol / L, 20 mmol / L, 23 mmol / L, 25 mmol / L, 27 mmol / L or 30 mmol / L; the content of the ammonia water in the copper source solution, calculated as NH3, is preferably 4-7 wt%, and specifically can be 4 wt%, 4.2 wt%, 4.5 wt%, 4.7 wt%, 5 wt%, 5.2 wt%, 5.5 wt%, 5.7 wt%, 6 wt%, 6.2 wt%, 6.5 wt%, 6.7 wt% or 7 wt%; the temperature of the hydrothermal synthesis is preferably 90-140℃, and specifically can be 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃ or 140℃; the time of the hydrothermal synthesis is preferably 8-12 h, and specifically can be 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, 11.5 h or 12 h, and most preferably 10 h.

[0037] In the preparation method provided in the present application, in step d), the hydrophobic silane coupling agent is preferably 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane; the modification is preferably carried out under vacuum; the temperature of the modification is preferably 70-90℃, and specifically can be 70℃, 72℃, 75℃, 77℃, 80℃, 82℃, 85℃, 87℃ or 90℃, and most preferably 80℃; the time of the modification is preferably 1-4 h, and specifically can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h.

[0038] The technical solution provided in the present application first activates the surface of the PTFE film by plasma bombardment technology, so that it has modifiability; then covers a nanoscale SiO2 thin layer on the surface of the activated film structure by chemical vapor deposition (CVD) technology, so that it can be constructed into a CuSiO3 nanoneedle structure by hydrothermal synthesis method at one time; finally, the film material is made to have strong hydrophobicity by modifying a hydrophobic silane coupling agent. The experimental results show that the water contact angle of the hydrophobic and breathable film provided in the present application is >140°, and the air permeability is reduced by <5% compared with the PTFE porous film before treatment.

[0039] For a clearer understanding, the following examples are provided for further illustration.

[0040] Example 1

[0041] A preparation method of a PTFE hydrophobic and breathable film, the flow is shown in Figure 1 , and the specific description is as follows:

[0042] Prepare a PTFE porous film (pore size about 3 μm, pore length 10 μm, porosity 70%, water contact angle 120°), and use air atmosphere to perform plasma bombardment activation on the surface of the film material; wherein the air pressure of the plasma bombardment is 20 Pa, the gas flow is set to 400 sccm, the power is set to 400 W, and the bombardment time is 3 min;

[0043] Under normal pressure conditions, use the ammonia catalytic tetraethyl orthosilicate hydrolysis condensation method to deposit a SiO2 nanolayer on the surface of the surface-activated PTFE film; wherein the deposition time is 12 h, and the SiO2 nanolayer formed by deposition is about 80 nm;

[0044] Add 1 mmol of copper acetate monohydrate, 20 mmol of ammonium chloride, and 2 mL of 28 wt% ammonia water into 100 mL of distilled water in sequence to form a uniform copper source solution; then transfer the copper source solution and the PTFE film with the deposited SiO2 nanolayer to a sealed reaction kettle for hydrothermal synthesis under the condition of 120℃ for 10 h, and grow CuSiO3 nanoneedle structures on the SiO2 nanolayer;

[0045] Use 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane as a hydrophobic silane coupling agent to perform hydrophobic modification on the CuSiO3 nanoneedle structures on the surface of the PTFE film; wherein the hydrophobic modification is performed under vacuum and at 80℃, and the processing time is 2 h; after the hydrophobic modification is completed, a PTFE hydrophobic and breathable film with CuSiO3 nanoneedle super-hydrophobic nanostructures constructed on the surface is obtained.

[0046] Figure 2 A real photo of an untreated PTFE porous film provided for Example 1 of the present application, Figure 3 A real photo of a PTFE hydrophobic and breathable film provided for Example 1 of the present application. Through Figures 2-3 comparison, it can be seen that after the PTFE porous film is treated by the method of the present example, a light blue modification layer is formed on the surface thereof.

[0047] Perform surface water contact angle testing on the PTFE hydrophobic and breathable film prepared in the present example, and the results are shown in Figure 4 . Figure 4 is a water contact angle testing result graph of the PTFE hydrophobic and breathable film provided for Example 1 of the present application. Through Figure 4 it can be known that the water contact angle of the PTFE hydrophobic and breathable film is 146°, and the PTFE hydrophobic and breathable film has super-hydrophobicity.

[0048] The untreated PTFE porous membrane and the PTFE hydrophobic and air permeable membrane prepared in the embodiment were observed by scanning electron microscope (SME), and the results are shown in Figure 5 Figure 5 FIG. 1 is a SEM image of the membrane material provided in Embodiment 1, wherein the upper left image is a SEM image of the untreated PTFE porous membrane (magnification × 10k), the upper right image is a SEM image of the PTFE hydrophobic and air permeable membrane (magnification × 10k), the lower left image is a SEM image of the PTFE hydrophobic and air permeable membrane (magnification × 50k), and the lower right image is a SEM image of the PTFE hydrophobic and air permeable membrane (magnification × 100k). Figure 5 It can be seen that the PTFE porous membrane forms a modified layer of nano needle structure on the surface after being treated by the method of the embodiment.

[0049] The air permeability of the untreated PTFE porous membrane and the PTFE hydrophobic and air permeable membrane prepared in the embodiment was detected, and the results showed that the air permeability of the untreated PTFE porous membrane was 4.5 × 10 -5 kg / (kPa·cm 2 ·s), and the air permeability of the PTFE hydrophobic and air permeable membrane prepared in the embodiment was 4.37 × 10 -5 kg / (kPa·cm 2 ·s), and the air permeability of the treated membrane was reduced by less than 5%.

[0050] In addition, according to the method provided in the embodiment, PTFE porous membranes with pore diameters of 1 μm, 1.5 μm and 2 μm were treated, and then air permeability detection was performed, and the results showed that the air permeability of the untreated PTFE porous membrane was 5.9 × 10 - 6 kg / (kPa·cm 2 ·s), 1.52 × 10 -5 kg / (kPa·cm 2 ·s), and 2.92 × 10 -5 kg / (kPa·cm 2 ·s), respectively, and the air permeability of the PTFE hydrophobic and air permeable membrane obtained after treatment was 5.73 × 10 -6 kg / (kPa·cm 2 ·s), 1.48 × 10 -5 kg / (kPa·cm 2 ·s), and 2.80 × 10 -5 kg / (kPa·cm 2 ·s), respectively, and the air permeability of the treated membrane was reduced by less than 5%.

[0051] ​Membrane-based liquid film boiling phase change cooling test: the related experiments are carried out in a test device composed of a liquid tank, a control valve, a two-phase heat sink, a gas permeable membrane, a temperature measuring thermocouple and a pressure gauge; during the experiment, mixed gas is introduced to provide pressure, and the liquid in the liquid tank is pumped into the surface of the heat sink, the gas permeable membrane is integrated above the two-phase heat sink, and the temperature measuring thermocouple and the pressure gauge measure the temperature in the experimental device and the pressure of the mixed gas respectively. The experimental conditions are set as follows: the transmembrane pressure difference ΔP provided by the mixed gas is 10 kPa, the liquid temperature in the liquid tank is set to 25°C; the distance between the gas permeable membrane and the surface of the heat sink is 1 mm; the gas permeable membrane used for membrane-based liquid film boiling phase change cooling is the PTFE hydrophobic gas permeable membrane prepared in the embodiment. The experimental results show that the PTFE hydrophobic gas permeable membrane prepared in the embodiment has a 20% improvement in the performance of the limiting heat flux density compared with the PTFE gas permeable membrane before treatment, and can realize kW-level heat dissipation demand.

[0052] Embodiment 2

[0053] A preparation method of a PTFE hydrophobic gas permeable membrane, the flow is as shown in Figure 1 , and the specific description is as follows:

[0054] Prepare a PTFE porous membrane (pore size about 3 μm, pore length 10 μm, porosity 70%, water contact angle 120°), and use air atmosphere to perform plasma bombardment activation on the surface of the membrane material; wherein the gas pressure of the plasma bombardment is 30 Pa, the gas flow is set to 600 sccm, the power is set to 600 W, and the bombardment time is 2 min;

[0055] Under normal pressure conditions, a SiO2 nanolayer is deposited on the surface of the surface-activated PTFE membrane by using the ammonia catalytic tetraethyl orthosilicate hydrolysis condensation method; wherein the deposition time is 12 h, and the SiO2 nanolayer formed by deposition is about 80 nm;

[0056] Add 1 mmol of copper acetate monohydrate, 20 mmol of ammonium chloride and 2 mL of 28 wt% ammonia water into 100 mL of distilled water in sequence to form a uniform copper source solution; then transfer the copper source solution and the PTFE membrane on which the SiO2 nanolayer is deposited into a sealed reaction kettle to perform hydrothermal synthesis, and grow CuSiO3 nanoneedle structures on the SiO2 nanolayer under the condition of 120°C for 10 h;

[0057] Use 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane as a hydrophobic silane coupling agent to perform hydrophobic modification on the CuSiO3 nanoneedle structures on the surface of the PTFE membrane; wherein the hydrophobic modification is performed under vacuum and at 80°C, and the processing time is 2 h; after the hydrophobic modification is completed, a PTFE hydrophobic gas permeable membrane with CuSiO3 nanoneedle super-hydrophobic nanostructures constructed on the surface is obtained.

[0058] The PTFE hydrophobic and breathable film prepared in the embodiment is observed by scanning electron microscope (SME), and the result shows that the surface of the PTFE porous film after being treated by the method in the embodiment forms a modified layer of nano needle structure.

[0059] The PTFE hydrophobic and breathable film prepared in the embodiment is tested for surface water contact angle, and the result shows that the water contact angle of the PTFE hydrophobic and breathable film is 145°, and the film has superhydrophobicity.

[0060] The untreated PTFE porous film and the PTFE hydrophobic and breathable film prepared in the embodiment are tested for air permeability, and the result shows that the air permeability of the untreated PTFE porous film is 4.5×10 -5 kg / (kPa·cm 2 ·s), the air permeability of the PTFE hydrophobic and breathable film prepared in the embodiment is 4.39×10 -5 kg / (kPa·cm 2 ·s), and the air permeability of the treated film is reduced by less than 5%.

[0061] Embodiment 3

[0062] A preparation method of a PTFE hydrophobic and breathable film, the flow is shown as Figure 1 follows, and the specific description is as follows:

[0063] A PTFE porous film (pore size about 3 μm, pore length 10 μm, porosity 70%, water contact angle 120°) is prepared, and the surface of the film material is activated by air plasma bombardment; wherein the air pressure of the plasma bombardment is 20 Pa, the gas flow is set to 400 sccm, the power is set to 400 W, and the bombardment time is 3 min;

[0064] Under normal pressure, a SiO2 nano layer is deposited on the surface of the surface-activated PTFE film by using the way of ammonia catalytic tetraethyl orthosilicate hydrolysis condensation; wherein the deposition time is 12 h, and the SiO2 nano layer formed by deposition is about 80 nm;

[0065] 1 mmol of copper acetate monohydrate, 20 mmol of ammonium chloride and 2 mL of 28 wt% ammonia water are sequentially added into 100 mL of distilled water to form a uniform copper source solution; then the copper source solution and the PTFE film on which the SiO2 nano layer is deposited are transferred into a sealed reaction kettle for hydrothermal synthesis, and CuSiO3 nano needle structure is grown on the SiO2 nano layer under the condition of 100 ℃ for 12 h;

[0066] The CuSiO3 nanoneedle structure on the surface of the PTFE film is hydrophobically modified by using 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane as a hydrophobic silane coupling agent; wherein the hydrophobic modification is performed under the conditions of vacuum and 80℃, and the processing time is 2h; after the hydrophobic modification, the PTFE hydrophobic and air-permeable film with a CuSiO3 nanoneedle super-hydrophobic nanostructure on the surface is obtained.

[0067] The PTFE hydrophobic and air-permeable film prepared in this embodiment is observed by scanning electron microscopy (SME), and the results show that the PTFE porous film forms a modified layer of nanoneedle structure on the surface after being treated by the method of this embodiment.

[0068] The PTFE hydrophobic and air-permeable film prepared in this embodiment is tested for surface water contact angle, and the results show that the water contact angle of the PTFE hydrophobic and air-permeable film is 147°, which has super-hydrophobicity.

[0069] The untreated PTFE porous film and the PTFE hydrophobic and air-permeable film prepared in this embodiment are tested for air permeability, and the results show that the air permeability of the untreated PTFE porous film is 4.5×10 -5 kg / (kPa·cm 2 ·s), and the air permeability of the PTFE hydrophobic and air-permeable film prepared in this embodiment is 4.36×10 -5 kg / (kPa·cm 2 ·s), and the air permeability of the treated film is reduced by less than 5%.

[0070] Embodiment 4

[0071] A preparation method of a PTFE hydrophobic and air-permeable film, the flow is as shown in Figure 1 , and the specific description is as follows:

[0072] Prepare a PTFE porous film (pore size about 2μm, water contact angle 120°), and use air atmosphere to perform plasma bombardment activation on the surface of the film material; wherein the air pressure of the plasma bombardment is 20Pa, the gas flow is set to 400sccm, the power is set to 400W, and the bombardment time is 3min;

[0073] Under normal pressure conditions, a SiO2 nanolayer is deposited on the surface of the surface-activated PTFE film by using the method of ammonia catalytic hydrolysis and condensation of tetraethyl orthosilicate; wherein the deposition time is 12h, and the SiO2 nanolayer formed by deposition is about 80nm;

[0074] A copper source solution was formed by sequentially adding 1 mmol of copper acetate monohydrate, 20 mmol of ammonium chloride and 2 mL of 28 wt% ammonia water into 100 mL of distilled water; then the copper source solution was transferred into a sealed reaction kettle together with the PTFE membrane on which SiO2 nanolayers were deposited to perform hydrothermal synthesis, and CuSiO3 nanoneedle structures were grown on the SiO2 nanolayers under the condition of 120°C for 10 h;

[0075] The CuSiO3 nanoneedle structures on the surface of the PTFE membrane were hydrophobically modified by using 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane as a hydrophobic silane coupling agent; wherein the hydrophobic modification was performed under the condition of vacuum and 80°C for 2 h; and after the hydrophobic modification, the PTFE hydrophobic and air permeable membrane with CuSiO3 nanoneedle super-hydrophobic nanostructures on the surface was obtained.

[0076] The PTFE hydrophobic and air permeable membrane prepared in this embodiment was observed by scanning electron microscopy (SME), and the results showed that the PTFE porous membrane formed a modified layer of nanoneedle structures on the surface after being treated by the method of this embodiment.

[0077] The PTFE hydrophobic and air permeable membrane prepared in this embodiment was tested for surface water contact angle, and the results showed that the water contact angle of the PTFE hydrophobic and air permeable membrane was 146°, which had super-hydrophobicity.

[0078] The untreated PTFE porous membrane and the PTFE hydrophobic and air permeable membrane prepared in this embodiment were tested for air permeability, and the results showed that the air permeability of the untreated PTFE porous membrane was 2.92×10 -5 kg / (kPa·cm 2 ·s), and the air permeability of the PTFE hydrophobic and air permeable membrane prepared in this embodiment was 2.83×10 -5 kg / (kPa·cm 2 ·s), and the air permeability of the treated membrane was reduced by less than 5%.

[0079] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A hydrophobic and breathable membrane, characterized in that, It is made by sequentially activating the surface of a PTFE porous membrane through plasma bombardment, depositing a SiO2 nanolayer through chemical vapor deposition, synthesizing a CuSiO3 nanoneedle structure through hydrothermal synthesis, and modifying it with a hydrophobic silane coupling agent.

2. A method for preparing the hydrophobic and breathable membrane according to claim 1, characterized in that, Includes the following steps: a) Plasma bombardment of the surface of a porous PTFE membrane yields a surface-activated PTFE membrane; b) A SiO2 nanolayer is deposited on the surface of the surface-activated PTFE film using chemical vapor deposition. c) A CuSiO3 nanoneedle structure was grown on the SiO2 nanolayer using a hydrothermal synthesis method; d) Modify the CuSiO3 nanoneedle structure with a hydrophobic silane coupling agent to obtain a hydrophobic and breathable membrane.

3. The preparation method according to claim 2, characterized in that, In step a), the plasma bombardment is carried out in an air or pure oxygen atmosphere; the pressure of the plasma bombardment is 10~30 Pa; the gas flow rate of the plasma bombardment is 200~600 sccm; the power of the plasma bombardment is 200~600 W; and the duration of the plasma bombardment is 2~5 min.

4. The preparation method according to claim 2, characterized in that, In step b), the deposition process specifically includes: Under normal pressure, a SiO2 nanolayer is deposited on the surface of the surface-activated PTFE film by ammonia-catalyzed hydrolysis and condensation of tetraethyl orthosilicate.

5. The preparation method according to claim 4, characterized in that, In step b), the deposition time is 8 to 24 hours.

6. The preparation method according to claim 2, characterized in that, In step b), the thickness of the SiO2 nanolayer is ≤100nm.

7. The preparation method according to claim 2, characterized in that, In step c), the process of growing CuSiO3 nanoneedle structures specifically includes: The PTFE membrane treated in step b) was mixed with a copper source solution and hydrothermal synthesis was carried out under closed conditions to grow CuSiO3 nanoneedle structures on the SiO2 nanolayer of the PTFE membrane.

8. The preparation method according to claim 7, characterized in that, In step c), the copper source solution contains copper acetate, ammonium chloride and ammonia; the hydrothermal synthesis temperature is 90~140℃; and the hydrothermal synthesis time is 8~12h.

9. The preparation method according to claim 2, characterized in that, In step d), the hydrophobic silane coupling agent is 1H,1H,2H,2H-perfluorodecyltriethoxysilane.

10. The preparation method according to claim 2, characterized in that, In step d), the modification is carried out under vacuum conditions; the modification temperature is 70~90℃; and the modification time is 1~4h.

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