Stable and durable uv-resistant superhydrophobic films and applications thereof

Abstract

The application belongs to the field of new materials, and relates to a stable and durable ultraviolet-resistant super-hydrophobic material and application thereof.The stable and durable ultraviolet-resistant super-hydrophobic material comprises a stable and durable ultraviolet-resistant super-hydrophobic film and a base material, the stable and durable ultraviolet-resistant super-hydrophobic film comprises a PMMA layer, a PET layer and a PSA layer in sequence, and the PSA layer of the stable and durable ultraviolet-resistant super-hydrophobic film is adhered to the base material.By adjusting the nanoparticle concentration of the PMMA layer on the PET and the drop-coating parameters, the bulk distribution state of SiO2 in the PMMA matrix is reasonably controlled.A transparent ultraviolet-resistant super-hydrophobic film with an ultrahigh ultraviolet reduction rate of 99.5%, wet abrasion resistance and the like is prepared.In addition, even after 12800 cycles of ethanol wet abrasion and 300 hours of weather resistance test, the TSURF can still maintain super-hydrophobicity, and can cope with bending and twisting deformation, high and low temperature environments and strong acid and alkali corrosion.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of new materials, and relates to an ultraviolet-resistant super-hydrophobic film, in particular a stable and durable ultraviolet-resistant super-hydrophobic film and application thereof. BACKGROUND

[0002] The glass curtain walls of global high-rise buildings have reached about 3 billion square meters, which will lead to higher cleaning costs and more indoor ultraviolet (UV) intake. Therefore, self-cleaning and light management surface materials are essential to address this trend. Ultraviolet light is essential to life on Earth; however, excessive ultraviolet radiation can damage organic bonds and is harmful to polymer products and even humans. Therefore, ultraviolet-resistant materials are needed to prevent the ultraviolet component in sunlight.

[0003] CN202011559689.3 discloses a blue light-resistant ultraviolet-resistant antibacterial hardening protective film and a preparation method, comprising an antibacterial hardening layer, a blue light-resistant ultraviolet-resistant layer and a substrate layer connected in sequence, the antibacterial hardening layer is adhered to the blue light-resistant ultraviolet-resistant layer by ultraviolet curing, and the blue light-resistant ultraviolet-resistant layer is adhered to the substrate layer by heat curing.

[0004] CN201710858982.1 relates to an ultraviolet-resistant protective film, comprising a substrate layer, a barrier layer for blocking ultraviolet light coated on the upper surface of the substrate layer, a puncture-resistant layer coated on the surface of the barrier layer, a static self-adhesive film layer formed and attached to the bottom surface of the substrate layer, and a release layer detachably attached to the bottom surface of the static self-adhesive film layer. The static self-adhesive film layer can be adsorbed on the surface of the object by static electricity, the puncture-resistant layer can effectively prevent the product from being punctured, and the object can be better protected, the product is more durable, and the damage of ultraviolet light to the product is prevented by the barrier layer to meet the use requirements.

[0005] However, the surface of such liquid films is generally not durable. The light management materials reported so far with super-hydrophobicity are often opaque, and it is still a challenge to achieve super-hydrophobicity, wet abrasion durability and transparency on optical materials. SUMMARY

[0006] The present application aims at the deficiencies of the prior art, and provides a stable and durable ultraviolet-resistant super-hydrophobic film and application thereof.

[0007] The present application provides a stable and durable anti-ultraviolet super-hydrophobic material, including a stable and durable anti-ultraviolet super-hydrophobic film and a substrate, the stable and durable anti-ultraviolet super-hydrophobic film sequentially includes a PMMA layer, a PET layer and a PSA layer, and the PSA layer of the stable and durable anti-ultraviolet super-hydrophobic film is adhered to the substrate. The substrate is glass, stainless steel, acrylonitrile-butadiene-styrene plastic (ABS), wood, leather, cloth and the like. Preferably, the total thickness of the stable and durable anti-ultraviolet super-hydrophobic film is about 75-85 μm.

[0008] Term explanation:

[0009] PMMA: polymethyl methacrylate; PSA: organic silicon pressure-sensitive adhesive; PET: polyethylene terephthalate.

[0010] Preferably, in the PMMA layer, nano-SiO2 is contained; the particle size of the hydrophobic fume nano-SiO2 is 5-40 nm. More preferably, the particle size of the hydrophobic fume nano-SiO2 is 5-10 nm. Preferably, the PMMA coating layer with the particle size of 7-10 nm SiO2 can have both transmittance and roughness.

[0011] Preferably, the stable and durable anti-ultraviolet super-hydrophobic film has an average transmittance of more than 85% in the visible light region; and the total thickness of the film is about 80 μm.

[0012] Preferably, in the test with anhydrous ethanol as a wet grinding medium, the water contact angle on the TSURF surface is greater than 150° after 6400 times of grinding cycles of the TSURF. After 12800 times of grinding cycles with anhydrous ethanol as a wet grinding medium, the water droplet contact angle hysteresis on the TSURF surface is only 3.81°, which indicates that the structure and chemical composition of the TSURF surface are almost not damaged in the wet grinding test process, and the lateral adhesion of water on the surface is very low. In the wet friction test with a detergent as a medium, the TSURF can still maintain excellent super-hydrophobic performance in about 6000 times of grinding cycles. In the air medium, the TSURF can withstand 110 times of wear cycles under a load of 100 g, and the contact angle is still greater than 150°.

[0013] The adhesion of the stable and durable anti-ultraviolet super-hydrophobic film to various substrates is more than 10 MPa. Among them,

[0014] Substrate Adhesion (MPa) Glass 20.73 Stainless Steel 18.44 Acrylonitrile-butadiene-styrene plastic (ABS) 15.26 Polished Wood 14.93 Leather 11.27

[0015] The stable and durable anti-ultraviolet super-hydrophobic film (TSURF) can withstand a tensile force of more than 86 MPa. After 1000 times of bending, the contact angle is still greater than 153°, and the rolling angle is less than or equal to 3.81°; after 1000 times of twisting, the contact angle is still greater than 153°, and the rolling angle is less than or equal to 3.06°.

[0016] The stable and durable anti-UV super-hydrophobic film (TSURF) can maintain its performance without any decay after 32 days of testing in the high temperature 70℃ and low temperature -45℃ testing environment. The TSURF can maintain its super-hydrophobicity (contact angle greater than 150°) after 108 hours of immersion in acidic condition and 60 hours of immersion in alkaline condition.

[0017] At the time point of the maximum light intensity, the UV intensity reaches 1540 μW·cm -2 , the UV intensity through the Low-E glass is 854 μW·cm -2 , and the UV intensity through the TSURF-glass is only 9.6 μW·cm -2 . The average UV blocking rate of the TSURF-glass is as high as 99.5% during the test, while the average UV blocking rate of the Low-E glass is only 45.8%.

[0018] The application also provides a preparation method of the stable and durable anti-UV super-hydrophobic film (TSURF), comprising the following steps,

[0019] S1, pressing the organic silicone pressure sensitive adhesive (PSA) to the back side of the film with anti-UV property by a film presser;

[0020] S2, dissolving the PMMA in the acetone solvent, then adding the nano-scale fumed hydrophobic SiO2 and performing ultrasonic oscillation until completely dispersed; preparing the acetone solution of the SiO2 mixed PMMA,

[0021] dropping and coating the acetone solution of the SiO2 mixed PMMA to the surface side of the pressed PET film;

[0022] S3, after the acetone is evaporated, a solid PMMA coating layer doped with SiO2 is formed above the PET film;

[0023] S4, hydrophobic treatment of the surface of the TSURF to obtain the UV blocking film (TSURF) with high adhesion and weather resistance.

[0024] The "back side" and "surface side" of the application only indicate the relative position of the film, i.e. one side of the film is the "back side" and the other side of the film is the "surface side".

[0025] Preferably, in step S2, the mass fraction of PMMA is 0-30wt%. Considering the excellent super-hydrophobicity and high transparency, the mass fraction of PMMA is 10-20wt%, and most preferably, the mass fraction of PMMA is 15wt%.

[0026] In the PMMA layer preparation, the particle concentration in unit volume is (0.4-2) x 10-3g.mL-1, and the volume of the drop-coated solution per unit area is 0.05-0.25 mL.cm-2, so that the average light transmittance can be more than 85%. In particular, when the particle concentration in unit volume is (0.4-1) x 10-3g.mL-1, and the volume of the drop-coated solution per unit area is 0.05-0.20 mL.cm-2, the average light transmittance can be more than 90%.

[0027] Preferably, in step S4, the plasma gas etching using CHF3 as the working gas is used to complete the etching. In the etching process, part of the PMMA is etched, and the dispersed silica is retained and forms the end of the synaptic structure, thereby forming a hierarchical three-dimensional rough structure on the TSURF surface.

[0028] Preferably, in step S4, the plasma gas etching process is performed in an inductively coupled plasma (ICP) etching system. CHF3 is used as the working gas to etch and fluorinate the film to obtain a transparent super-hydrophobic film. The fluorination etching treatment temperature is -5-5°C, and the treatment time is 15-25 s. In the etching process, the gas pressure is set to 0.7-0.9 Pa, the working flow rate is 0.05-0.07 L / min, the upper electrode ICP power is set to 180-220 W, and the lower electrode RF power is set to 8-12 W.

[0029] We also provide the use of the stable and durable anti-ultraviolet super-hydrophobic material for photovoltaic materials.

[0030] We designed a stable and durable anti-ultraviolet super-hydrophobic film (TSURF) with high transparency, which can be mass-produced by lamination and plasma gas etching. An anti-ultraviolet polyethylene terephthalate (PET) layer is used as an intermediate layer, and a pressure-sensitive adhesive (PSA) layer is used for lamination at the bottom to provide excellent adhesion to various substrates.

[0031] The TSURF shows selective transmission to incident light, maintaining high transmittance in the visible light region (400-800 nm) while reflecting almost all ultraviolet light (10-380 nm). In addition, the TSURF can withstand various external force deformations and acid / alkali chemical environments, and can maintain excellent super-hydrophobic properties at different temperature environments. Notably, the TSURF can still maintain super-hydrophobicity after more than 10,000 wet abrasions using ethanol and surfactants. At the same time, it has excellent dustproof, self-cleaning, and weather resistance, which makes it widely applicable in the fields of building glass, photovoltaic energy, etc. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The preparation flow chart of stable and durable anti-ultraviolet super-hydrophobic film TSURF.

[0033] Figure 2 is the macroscopic and microscopic characterization of TSURF, wherein (a) is a photograph of TSURF pasted on glass, (b) is a SEM image of the surface and interface of TSURF.

[0034] Figure 3 The influence of PMMA mass fraction on the visible light transmittance and the hydrophobicity of the material. (a) is a schematic diagram of the influence of the roughness distribution density of the material surface on the hydrophobicity and the scattering / refraction of incident light; (b) is a curve of the average transmittance of TSURF in the visible light region with the change of PMMA mass fraction; (c) is a curve of the water contact angle on the surface of TSURF with the change of PMMA mass fraction.

[0035] Figure 3 The SEM image and the local enlarged image of the surface of TSURF.

[0036] Figure 3 The high and low temperature resistance and acid and alkali stability test of TSURF. (a) is a curve of the contact angle and the rolling angle of water on the surface of TSURF with the change of the number of days of high temperature environment test; the red data line is the change of the contact angle with the abrasion cycle, and the blue line is the change of the rolling angle with the abrasion cycle. (b) is a curve of the contact angle and the rolling angle of water on the surface of TSURF with the change of the number of days of low temperature environment test; the red data line is the change of the contact angle with the abrasion cycle, and the blue line is the change of the rolling angle with the abrasion cycle. (c) is a curve of the contact angle and the rolling angle of water on the surface of TSURF with the change of the number of days of strong acid resistance test; the red data line is the change of the contact angle with the abrasion cycle, and the blue line is the change of the rolling angle with the abrasion cycle. (d) is a curve of the contact angle and the rolling angle of water on the surface of TSURF with the change of the number of days of strong alkali resistance test; the red data line is the change of the contact angle with the abrasion cycle, and the blue line is the change of the rolling angle with the abrasion cycle.

[0037] Figure 3 The test of ultraviolet blocking performance.

[0038] Figure 4 The photograph of the weather resistance test equipment.

[0039] Etching Time (s) The comparison photographs of different samples before and after the weather resistance test. (a) is the comparison photographs of the original glass before and after the weather resistance test; (b) is the comparison photographs of TSURF-glass before and after the weather resistance test; (c) is the comparison photographs of the original stainless steel before and after the weather resistance test; (d) is the comparison photographs of TSURF-stainless steel before and after the weather resistance test.

[0040] Thin Film Hydrophobicity (Water Contact Angle, °) Hydrophobicity comparison of Low-E glass and TSURF-glass before and after weather resistance test.

[0041] Visible Light Transmittance (%) Physical photos of original PV panel and TSURF attached panel. Among them, (a) photos of TSURF attached PV panel before and after outdoor test, respectively, (b) photos of original PV before and after outdoor test, respectively.

[0042] Wet Abrasive Medium Performance of TSURF applied to PV panel. DETAILED DESCRIPTION

[0043] Experimental materials and instruments

[0044] Fumed hydrophobic silica, SiO2, analytical pure, Aldrich Group; polymethyl acrylate, (C5O2H8) n , analytical pure, Aldrich Group; organosilicon pressure-sensitive adhesive, commercial adhesive, Shenzhen KANGLIBANG; polyethylene terephthalate film, (C 10 H8O4) n , finished film, Dongguan Nanyu Technology Co., Ltd.; acetone, C3H6O, analytical pure, Thermo Fisher Scientific; hydrochloric acid, HC1, analytical pure, Aldrich Group. PET film is a thin film modified by ultraviolet blocking, purchased from Dongguan Nanyu Technology Co., Ltd.

[0045] Full-automatic film pressing machine, JXA-8530F PLUS type, Jinan Wancai Numerical Control Equipment Co., Ltd.; inductively coupled plasma etching system, PlasmaPro 100 type, Oxford Instruments (UK) Ltd.; ultraviolet radiation intensity meter, UV type, Linshang Technology Co., Ltd.

[0046] Test and characterization

[0047] Surface wetting property test

[0048] The contact angle and roll-off angle of water droplets on the TSURF surface were measured using a KRϋSS DSA25S optical contact angle analysis system. For the measurement of the contact angle in non-moving state, water droplets (~10 μΐ) were first added to the sample surface by a syringe controlled by a motor. When the droplet was stable, a side-view image was taken by a camera and the software was used to calculate the static contact angle of water droplets on the TSURF surface. For the measurement of the roll-off angle, the sample was tilted using a rotatable test platform controlled by a motor and the rotation angle of the platform was displayed in real time on a computer connected to the motor. The initial tilt angle of the platform was kept at 0° at the beginning of the test. After water droplets (~10 μΐ) were added to the TSURF surface by a syringe, the platform was rotated by controlling the motor. The rotation was stopped at the moment when the droplet started to roll on the surface and the rotation angle displayed on the computer was recorded as the roll-off angle. Each sample was measured at three different locations to reduce the error of the data.

[0049] Scanning electron microscope (SEM) characterization

[0050] Scanning electron microscope (SEM) observation was performed on a SUPRA TM 55field emission scanning electron microscope (Zeiss, Germany). After the preparation of TSURF, the sample with a size of 2 mm x 2 mm was cut for the characterization of the surface morphology and cross-section. Meanwhile, the distribution map of Si element on the surface of TSURF was also scanned.

[0051] Visible light transmittance test

[0052] The transmittance of visible light of TSURF was tested using a UV-vis spectrophotometer. The size of the test sample was 7.5 cm x 2.5 cm and a glass slide with the same size was selected as the control sample during the test. The transmittance of air was set as the baseline of the test. The test wavelength range was 400 nm to 800 nm.

[0053] X-ray photoelectron spectroscopy (XPS) analysis

[0054] The XPS analysis was performed using an X-ray photoelectron spectrometer (Al-Ka X-ray as the light source) and the instrument parameters were set as follows during the test: test voltage 15 kV, test power 300 W. The elements on the surface of TSURF were quantitatively analyzed.

[0055] Mechanical stability test

[0056] Wet abrasion resistance test: During the test, the friction contact of the friction tester was covered with a coarse cotton cloth and the contact area with the TSURF surface was about 0.785 cm 2, with a load mass of 1 kg. The rubbing contact was able to move 3 cm in one direction on the surface, defining one reciprocation as one rubbing cycle (6 cm movement). After every 10 rubbing cycles, 0.5 mL of ethanol or detergent medium was added to the fabric to keep the cheesecloth wet. After each rubbing test for a certain number of cycles, the contact angle and roll-off angle of water droplets on the TSURF surface were measured to evaluate its wet rub resistance.

[0057] Dry abrasion resistance test: The dry abrasion resistance of TSURF was tested according to ASTM test standard (D4060) using a Taber abrasion tester. Two load wheels with a load of 100 g were used to perform the abrasion test on a TSURF surface with a diameter of 10 cm. After each abrasion test for a certain number of cycles, the contact angle and roll-off angle of water droplets on the TSURF surface were measured as an indicator of the Taber abrasion resistance of TSURF.

[0058] Adhesion test: To test the adhesion of the coating to different substrates, we refer to the GB / T 5210-2006 standard and use an adhesion tester to test the adhesion between TSURF and various substrates using a mechanical pull-off method. First, the spindle is bonded to the coating using a special glue for the test instrument, and it is dried at room temperature for more than 72 hours to ensure that the spindle is completely bonded to the coating. Then, a cutter is used to cut a circle around the spindle and through the coating. Then, the unload valve on the test machine is completely loosened counterclockwise, the black piston on the quick sleeve is pressed down by hand to connect the quick sleeve to the spindle, the instrument is set to "peak test" state and zeroed, the unload valve is tightened for pressure testing, and the peak pressure shown at the moment when the coating adhered to the spindle separates from the substrate is the adhesion of the coating to the substrate.

[0059] Stress-strain test: Strain-Stress curve data was obtained by testing on a universal tensile testing machine. The tested TSURF sample was 1 cm wide, 3 cm long, and about 90 μm thick. The test speed was 10 mm / min.

[0060] High / low temperature stability test: In the TSURF high / low temperature environment stability test, 70°C was selected as the high temperature environment and -45°C as the low temperature environment for subsequent testing. During the test, the contact angle and roll-off angle of water droplets on the TSURF surface were measured every four days to evaluate its stability.

[0061] Chemical stability test

[0062] Chemical stability test was conducted in 2.5M strong acid (hydrochloric acid) and 2.5M strong base (sodium hydroxide) solution, respectively. During the test, the TSURF was completely immersed in the solution, and the contact angle and roll-off angle of water droplets on the TSURF surface were measured every 12 hours to evaluate its stability.

[0063] UV blocking performance test

[0064] We use UV irradiation intensity meter (China Linshang Technology) to measure the intensity of UV light. From sunrise, the intensity of UV light of original sunlight, through Low-E glass and through TSURF-glass is measured at selected fixed test positions respectively, and the interval of each test is 15 minutes.

[0065] Weather resistance test

[0066] Weather resistance test is carried out in UV accelerated aging tester. The intensity of UV simulated light source in the test is constant at 1.38 W / m 2 , and the blackboard temperature is 50℃. The simulated rainfall spray is carried out every 2 hours, and the spray lasts for 1 hour, and the spray amount is about 1 L / h.

[0067] Sand dust resistance test

[0068] Sand dust resistance test is carried out in sand dust test box, and special talc powder (particle size 1250 mesh) is used to simulate sand dust. During the test, the sample is vertically placed in the test room, and the talc powder is continuously blown out from the built-in air outlet at the bottom to simulate the real dusty environment. After a certain test time, the sample is taken out to observe the accumulation of surface sand dust, and then the surface self-cleaning ability is observed by using flowing water to clean.

[0069] Photovoltaic power generation performance test

[0070] The photovoltaic panel used in the photovoltaic power generation performance test is a commercial silicon-based photovoltaic power generation panel, and WT5000 power analyzer is used to calculate the power generation power. During the test, the voltage input port is connected in parallel with the photovoltaic panel, and the current port is connected in series with the output port of the photovoltaic panel.

[0071] The following examples are further illustrations of the application, which is not limited thereto.

[0072] Example 1

[0073] Preparation and synthesis of TSURF (ultraviolet first group film)

[0074] The preparation process of TSURF is as follows Friction Cycles (times)The commercial organic silicone pressure sensitive adhesive (PSA) was first pressed to the back side of the PET film with UV resistance by a laminator. Then the PMMA solution mixed with hydrophobic fumed nano-SiO2 was drop-coated to the surface side of the pressed PET film. After the acetone evaporated, a solid PMMA coating layer doped with SiO2 was formed on top of the PET film. The further hydrophobization treatment of the TSURF surface was done by plasma gas etching using CHF3 as working gas. During the etching process, part of the PMMA was etched, while the dispersed SiO2 was reserved and constituted the end of the synapse structure, forming a hierarchical three-dimensional rough structure on the TSURF surface.

[0075] Laminating process

[0076] The laminating process was performed on a full-automatic laminator, and the organic silicone pressure sensitive adhesive (PSA) was laminated to one side of the polyethylene terephthalate (PET) film. The working temperature, roller conveying speed and working air pressure were all set as the default settings of the machine.

[0077] PMMA coating

[0078] The polymethyl methacrylate (PMMA) was first dissolved in acetone solvent, and fumed hydrophobic nano-SiO2 was added and ultrasonically treated until completely dispersed. Then it was coated onto the PET surface by drop-coating, and after the acetone completely evaporated, it showed a uniform PMMA layer. In the preparation of the PMMA layer, the concentration of nano-SiO2 was 1×10 -3 g·mL -1 , the mass fraction of PMMA was 15wt%, and the drop-coating parameters were 0.2mL·cm -2 . Unless otherwise specified, "PET", "PET film" and "PET film" in this paper are all polyethylene terephthalate films modified with UV resistance, also known as films with UV resistance.

[0079] Plasma gas etching

[0080] The plasma gas etching process was performed in an inductively coupled plasma (ICP) etching system. CHF3 was used as the working gas for etching and fluorination of the film to obtain a transparent superhydrophobic film. The fluorination etching treatment temperature was 0°C, and the treatment time was 20s. The gas pressure was set to 0.8Pa during the etching process, and the working flow rate was 0.06L / min. The upper electrode ICP power was set to 200W, and the lower electrode RF power was set to 10W.

[0081] After etching, TSURF shows excellent superhydrophobicity and can be adhered to the surface of various substrate materials. In addition, TSURF has very high transparency and can be prepared on a large scale. Figure 2.a is a photograph of TSURF adhered to a glass substrate with a size of 85 cm x 25 cm, and TSURF has an average transmittance of more than 85% in the visible light region. As can be seen from the SEM image, the surface of TSURF shows a uniform nanoscale rough structure, which enables the visible light wave to pass through TSURF with as little reflection and scattering as possible, thereby ensuring high transparency. The cross-sectional SEM image of TSURF clearly shows the PMMA layer, the PET layer and the PSA layer, and the total thickness of the film is about 80 μm (as shown in Figure 2.b).

[0082] Therefore, the obtained high-adhesion and weather-resistant ultraviolet blocking film comprises, in sequence, a PMMA layer, a PET layer and a PSA layer, and the total thickness of the film is about 75-85 μm; the PSA layer of the high-adhesion and weather-resistant ultraviolet blocking film is adhered to a substrate to obtain a high-adhesion and weather-resistant ultraviolet blocking material. The substrate is glass, stainless steel, acrylonitrile-butadiene-styrene plastic (ABS), wood, leather, cloth and the like.

[0083] Example 2

[0084] Other than Example 1, the difference is that the particle size of the nano-SiO2 in the PMMA hydrophobic layer is different. We dispersed hydrophobic nano-SiO2 with different particle sizes (5-40 nm) in the acetone solvent of PMMA, and characterized the transmittance in the visible light region of the PMMA coating formed after the evaporation of acetone.

[0085] The PMMA hydrophobic layer has a crucial influence on the performance of TSURF, especially the SiO2 dispersed therein. In the preparation of a polymer material doped with particles, the dispersion degree of the micro-nano particles in the solvent is often difficult to reach an ideal state, and is often accompanied by irregular agglomeration of the micro-nano particles, which leads to the actual particle size of the filler in the material often being larger than the theoretical particle size. Therefore, the particle size selected for the preparation of a transparent material needs to be strictly selected. In particular, in the case of preparing a transparent superhydrophobic material, too small a particle size will increase the transparency, but will also result in insufficient roughness to provide superhydrophobicity; and too large a particle size will result in a loss of transparency.

[0086] We choose the particles with larger size to help us to achieve the desired roughness in the subsequent fabrication process. We dispersed the hydrophobic nano-SiO2 with different size (5-40nm) in the PMMA acetone solution, and characterized the PMMA coating formed after the evaporation of acetone in the visible region. As shown in Table 1, for the PMMA coating dispersed with SiO2 with size larger than 7-10nm, the transmittance in the visible region drops to below 80%, and the visual blurring appears before etching. In contrast, although the PMMA coating dispersed with 5nm SiO2 can achieve more than 90% transmittance in the visible region, we finally choose 7nm SiO2 as the filler to construct the largest possible roughness, which maintains the transmittance close to 90%. We prefer the PMMA coating dispersed with 5-10nm SiO2, which can have both transmittance and roughness.

[0087] Table 1 The effect of SiO2 size

[0088]

[0089]

[0090]

[0091]

[0092] Example 3

[0093] Other than Example 1, the difference is that the particle concentration in unit volume and the volume of the solution dropped in unit area of the PMMA hydrophobic layer are different. The particle concentration in unit volume of the PMMA hydrophobic layer is (0.4-2)xlO -3 g·mL -1 The volume of the solution dropped in unit area is 0.05-0.25mL-cm -2 was explored.

[0094] Table 2 The effect of particle concentration and the volume of the solution dropped

[0095]

[0096] In the actual situation, the transmittance of visible light is not only determined by the particle size, but also depends on the particle concentration in unit volume and the volume of the solution dropped in unit area. Through experiments, we found that the average transmittance of visible light decreases with the increase of particle concentration (as shown in Table 2); similarly, the more solution dropped in unit area, the more particles deposited, and the lower the average transmittance of visible light (as shown in Table 2). In order to maintain the transmittance of about 90%, we finally choose the particle concentration in unit volume to be 1xl0-3 g·mL -1 The volume of the solution per unit area is 0.2 mL·cm -2 The optimal parameters for preparing the PMMA layer are as follows: the particle concentration in the unit volume is (0.4-2)×10 -3 g·mL -1 The volume of the solution per unit area is 0.05-0.25 mL·cm -2 The average light transmittance is more than 85%. The particle concentration in the unit volume is (0.4-1)×10 -3 g·mL -1 The volume of the solution per unit area is 0.05-0.20 mL·cm -2 The average light transmittance is more than 90%.

[0097] Example 4

[0098] The difference between the example 1 and the example 4 is that the mass fraction of PMMA is different.

[0099] The mass fraction of PMMA in the solution also affects the performance of the material, which directly controls the distribution of nanoparticles in the material. As shown in Water Contact Angle (°) , the higher the mass fraction of PMMA, the thicker the PMMA layer, and the less SiO2 distributed per unit volume. According to Snell's law, the greater the difference in refractive index between the two media, the higher the refractive index of light. As shown in Rolling Angle (°) i in a, after etching, the higher the PMMA concentration, the less the surface roughness, and the more uniform the matrix, which will help to reduce the scattering of incident light and improve transparency, but it will lead to a decrease in hydrophobicity, and the contact angle of water droplets on the surface is usually less than 150°. For low-concentration PMMA, the situation is just the opposite, as shown in Water Contact Angle Hysteresis (°) ii in a. Therefore, only when the appropriate mass fraction of PMMA is added, can a reasonable surface structure be constructed, while showing excellent superhydrophobicity and high transparency (as shown in Ethanol iii in a).

[0100] The mass fraction of PMMA is 0-30 wt%, and the transparency can reach more than 85%. The mass fraction of PMMA is 10-30 wt%, and the transparency can reach more than 89%.

[0101] The mass fraction of PMMA is 0-30 wt%, and the water contact angle is more than 150°. The mass fraction of PMMA is 0-20 wt%, and the contact angle of the surface is more than 153°.

[0102] Therefore, in consideration of excellent superhydrophobicity and high transparency, the mass fraction of PMMA is 10-20wt%, and most preferably, the mass fraction of PMMA is 15wt%.

[0103] Example 5

[0104] Other than Example 1, the difference is that the etching time is different.

[0105] The hydrophobicity and transparency of TSURF are also affected by the etching time. Nanoparticles exhibit stronger scattering effect in air phase than in polymer, and longer etching time means more PMMA is etched by working gas, which will lead to the decrease of material transparency, but the superhydrophobicity will increase accordingly (as shown in Table 3).

[0106] The etching time is about 20 seconds, and high hydrophobicity and high material transparency can be obtained.

[0107] After exploring the experimental conditions, the best preparation conditions of TSURF are determined as follows: 7nm hydrophobic SiO2 is dispersed into the solution dissolved with 15wt% PMMA at a concentration of 1x10 -3 g·mL -1 , then 0.2mL·cm -2 is drop-coated on the surface of PET / PSA film, and then CHF3 is used as working gas for etching for 20 seconds. The surface of TSURF exhibits a unique hierarchical rough structure (as shown in Ethanol ), and after gas etching, the aggregated SiO2 particles are not etched, the middle is prismatic PMMA, and the agglomerates of SiO2 exhibit different depth distribution, forming a multi-level rough structure on the surface, which provides excellent superhydrophobicity in cooperation with CHF3 fluorination.

[0108] Table 3 Influence of different plasma gas etching time on the hydrophobicity and visible light transmittance of the film

[0109] Ethanol Ethanol Ethanol 0 123.18 87.83 10 147.36 87.18 20 155.10 84.27 30 156.25 64.37 40 156.87 46.29 50 157.72 43.64 60 159.03 42.73

[0110] Example 6 Stability test of TSURF

[0111] Durability has always been the main issue limiting the practical application of superhydrophobic materials, as it usually determines the service life of the materials. Although there have been many studies on improving the external abrasion resistance of superhydrophobic materials, their exploration process is usually carried out in air medium. However, in the practical application of superhydrophobic surfaces, more complex environments usually need to be dealt with, such as organic detergents or surfactant mixtures used in surface cleaning processes. We tested the wet abrasion resistance of TSURF here. The test method for wet abrasion resistance is as follows: wet abrasion tests were performed on a multifunctional ethanol abrasion tester (Hongjin Technology Co., Ltd., China). During the test, the friction contact of the friction tester was covered with a coarse cotton cloth, and the contact area between the friction contact and the TSURF surface was about 0.785 cm 2 , the friction load mass was 1 kg, the friction head could move 3 cm on the surface in one direction, and the movement of 6 cm was defined as one cycle. After every 10 cycles, 0.5 mL of ethanol or detergent medium was added to the fabric to keep the friction coarse cotton cloth wet. Then the contact angle and rolling angle of water on the material surface were measured after a certain number of friction cycles to characterize the wetting performance of the material and measure the material's ability to resist wet abrasion.

[0112] In the test with anhydrous ethanol as the wet abrasion medium, the contact angle of water on the TSURF surface decreased from the initial 154.68° ± 2.21° to 148.29° ± 4.47°, and the rolling angle increased from the initial 2.13° ± 0.36° to 14.21° ± 2.43° after 12800 friction cycles (as shown in Table 4). We also characterized the contact angle hysteresis (CAH) of water droplets on TSURF. CAH is the difference between the advancing contact angle (θ Adv ) and the receding contact angle (θ Rec ) of a liquid when it moves laterally on a solid surface (as shown in Table 4), and is usually considered to be related to the lateral adhesion of the droplet on the material, as well as reflecting the uniformity of the material surface structure and chemical composition. After 12800 friction cycles, the contact angle hysteresis of water droplets on the TSURF surface was only 3.81° ± 1.42°, indicating that the surface structure and chemical composition of TSURF were almost not damaged during the wet abrasion test, and the lateral adhesion of water on the surface was very low.

[0113] Table 4 Friction test of wet abrasion medium

[0114] Ethanol Detergent Detergent Detergent Detergent Detergent 0 154.68 2.13 0.27 Detergent 800 153.68 6.70 1.69 Wear Cycles (times) 1600 152.97 7.31 2.02 Contact Angle (°) 3200 151.76 11.32 2.64 Rolling Angle (°) 6400 150.47 12.76 3.22 Wear Cycles (times) 12800 148.29 15.21 3.81 Contact Angle (°) 0 155.21 2.77 0.42 Rolling Angle (°) 800 152.68 6.93 1.71 Substrate 1600 151.77 8.5 2.37 Adhesion (MPa) 3200 150.43 10.67 3.02 Glass 6400 149.13 12.81 3.65 Stainless Steel 10000 147.69 14.69 4.33

[0115] We then replaced the wet grinding medium with detergent and performed a similar wet rubbing test. Unlike ethanol, the composition of detergent is more complex, which is mainly composed of various surfactants. Nevertheless, TSURF was still able to maintain excellent superhydrophobic performance in about 6000 grinding cycles (as shown in Table 4), which is not achieved by many superhydrophobic surfaces.

[0116] Table 5 Dry abrasion resistance of TSURF in air medium

[0117] Acrylonitrile-butadiene-styrene plastic (ABS) Polished Wood Leather Bend Cycles Contact Angle (°) Rolling Angle (°) 0 155.68 2.13 20 152.43 6.43 1 155.17 2.65 30 152.07 7.06 2 154.86 2.98 40 151.76 7.71 3 154.27 3.41 50 151.37 8.58 4 153.95 3.86 70 150.82 10.21 5 153.44 4.54 90 150.71 13.69 10 153.19 5.17 110 150.56 17.47 15 152.73 5.92 130 145.53 24.91

[0118] Similarly, we tested the dry abrasion resistance of TSURF in air medium according to ASTM D4060. As shown in Table 5, under a load of 100g, TSURF was able to withstand 110 abrasion cycles without losing superhydrophobicity (contact angle greater than 150°). Given that the application scenario of this material design is the high-altitude building glass industry and the surface of photovoltaic power generation equipment, the abrasion of its surface is relatively less, we expect that the current dry abrasion resistance of TSURF can fully meet the work of modifying the surface of such high-altitude interface.

[0119] Example 7 Adhesion test

[0120] In addition to excellent abrasion resistance, TSURF also showed excellent adhesion to various substrates (as shown in Table 6). We tested the adhesion of TSURF on glass, stainless steel and acrylonitrile-butadiene-styrene plastic (ABS) surfaces. The adhesion of TSURF to glass, which has a surface rich in polar hydroxyl groups, was as high as 20.73±1.71MPa. Even on the surface of polished wood or waxed leather, the adhesion can reach 14.39±1.21MPa and 11.27±2.46MPa, respectively. This indicates that TSURF can be applied to the surface of various substrate materials without easily falling off.

[0121] Table 6 Adhesion of TSURF on different substrate materials

[0122] Bend Cycles Contact Angle (°) Rolling Angle (°) 20.73 Twist Cycles 18.44 Contact Angle (°) 15.26 Rolling Angle (°) 14.93 Twist Cycles 11.27

[0123] Example 8 Mechanical durability test

[0124] As a flexible film material, its mechanical performance indicators can also reflect the mechanical durability of the material, which is key to evaluating whether the film material can maintain surface performance under the influence of external force causing deformation.

[0125] Table 7 Stress-strain curve of TSURF

[0126]

[0127] As can be seen from the stress-strain of TSURF (as shown in Table 7), TSURF has high tensile strength and can withstand thousands of twisting (as shown in Table 8) and bending tests (as shown in Table 9). With the increase of stress, the strain of TSURF also increases, and TSURF can withstand a tensile force of more than 86 MPa. After 1000 times of bending, the contact angle is still greater than 153°, and the rolling angle is less than or equal to 3.81°; after 1000 times of twisting, the contact angle is still greater than 153°, and the rolling angle is less than or equal to 3.06°.

[0128] Table 8 Hydrophobic properties of TSURF in bending test with test cycle number

[0129] Contact Angle (°) Rolling Angle (°) Figure 5 Figure 5 Figure 5 Figure 5 0 155.68 2.13 100 155.6 2.26 10 155.71 2.39 200 155.32 2.62 20 155.56 2.41 300 155.27 2.17 30 155.43 2.86 400 155.15 2.88 40 155.28 2.42 500 154.97 2.9 50 155.11 2.53 1000 153.54 3.81

[0130] Table 9 Hydrophobic properties of TSURF in twisting test with test cycle number

[0131] Figure 6 Figure 7 Figure 8 Figure 8 Figure 9 Figure 9 0 155.68 2.13 100 155.35 2.71 10 155.42 2.44 200 155.45 2.46 20 155.53 2.31 300 155.36 2.69 30 155.63 2.26 400 155.13 2.79 40 155.46 2.54 500 154.69 2.86 50 155.27 2.56 1000 154.37 3.06

[0132] Example 8 Stability in extreme environments

[0133] We tested its stability in high-temperature and subzero low-temperature environments. In the test environment of high temperature 70℃ and low temperature -45℃, TSURF can be used without any performance decay after 32 days of testing (as shown in Figure 10 a and Figure 10 b), which means that TSURF can be used in most areas around the world. We also characterized the chemical stability of TSURF by immersing TSURF in 2.5M HCl and 2.5M NaOH solutions respectively to test its chemical stability in strong acid and strong base conditions, and measured the contact angle and rolling angle of water on the surface of TSURF every 12 hours of immersion. As shown in Figure 11 c and ​ d, TSURF can withstand 108 hours of immersion in acidic conditions, and TSURF can also withstand 60 hours of immersion in alkaline conditions, indicating that TSURF also has excellent chemical stability.

[0134] Example 9

[0135] Performance characterization of TSURF UV blocking and weather resistance of TSURF

[0136] The UV protection performance of TSURF was characterized using an ultraviolet radiometer. During the test, TSURF was attached to ordinary glass (hereinafter referred to as TSURF-glass), and commercially available single-layer Low-E glass was selected as a control sample. The test period was from sunrise (07:00 AM) to sunset (17:50 PM). Every 15 minutes during the test, the solar UV intensity, the UV intensity transmitted through the Low-E glass, and the UV intensity transmitted through the TSURF-glass were measured. ​ As shown, at the point of maximum light intensity, the ultraviolet radiation intensity reached 1540 μW·cm. -2 The intensity of ultraviolet light passing through Low-E glass is 854 μW·cm. -2 The ultraviolet intensity passing through TSURF-glass is only 9.6 μW·cm. -2 During testing, TSURF glass achieved an average UV blocking rate of 99.5%, while Low-E glass only achieved an average UV blocking rate of 45.8%.

[0137] In addition, to simulate the stability of TSURF in more complex environments, we conducted weathering resistance tests according to GB / T1766-95 standard. The tests were carried out in an aging test chamber, where high-intensity ultraviolet light was applied and simulated rainfall was simulated (e.g., ​ As shown in the figure, this test can verify the structural strength and surface composition stability of surface materials under outdoor conditions. Aging resistance tests were conducted on pristine glass, TSURF-glass, Low-E glass, and pristine stainless steel and stainless steel with TSURF coating (hereinafter referred to as TSURF-stainless steel) under the same conditions. ​ a to ​ As shown in d, after 100 hours of testing, the surfaces of the original glass and original stainless steel had accumulated a large amount of water stains, while the TSURF-glass and TSURF-stainless steel were very clean.

[0138] For commercially available Low-E glass, some water stains also accumulate on the surface, and most importantly, it loses its original waterproof performance (e.g., ​ As shown in the two images on the left), TSURF glass still maintained excellent superhydrophobic properties after testing (e.g., ​ As shown in the two figures on the right, this indicates that TSURF has stronger weather resistance than the already commercialized Low-E coating, meaning that TSURF has the potential to be promoted in the architectural glass industry and achieve commercialization.

[0139] Example 10

[0140] Performance of TSURF in photovoltaic (PV) materials

[0141] As the main component of photovoltaic power generation, the light-receiving surface of photovoltaic panels needs to be kept clean to ensure power generation efficiency. Most of the currently used silicon-based photovoltaic materials perfectly match the optical performance of TSURF for visible light and short-wave near-infrared light, and can prevent damage to the EVA and TPE / TPT structure of the back panel in photovoltaic panels. To test the improvement of the self-cleaning performance of TSURF on the easy-to-pollute phenomenon of the surface of photovoltaic materials, we conducted a test lasting for 1 year under actual environmental test conditions, and the test samples were placed outdoors throughout the test, and the daily power generation changes were detected in real time during the test. As shown in ​ a and ​ b, the surface of the PV panel with TSURF attached to the surface (hereinafter referred to as TSURF-PV panel) is cleaner than the original PV panel, and the original PV panel has accumulated dust and water stains after being washed by rain, while the surface of the TSURF-PV panel has hardly changed, which helps to ensure stable input light intensity and improve power generation efficiency. To quantify the performance of TSURF in improving the power generation efficiency of PV components, we measured the power generation of two PV panels with the same area in a year (as shown in ​ ). In the initial stage of the test, the power generation of the TSURF-PV panel is slightly lower than that of the original PV panel, which may be due to the weakening of SiO2 on the surface of TSURF to the incident light. With the passage of time, the accumulation of surface pollutants causes more reflection and refraction of light on the surface of the original panel, resulting in a decrease in actual light input and a decrease in power generation. On the other hand, the TSURF-PV panel maintains a high level of power generation due to its excellent surface self-cleaning ability, and the surface can always remain clean, with an increase of nearly 66.89% in annual power generation compared with the original PV panel.

[0142] In summary, we reasonably controlled the bulk distribution state of SiO2 in the PMMA matrix by adjusting the nanoparticle concentration and drop-coating parameters of the PMMA layer on PET. After plasma gas etching with CHF3, a nanoscale hierarchical structure was formed. Combined with simple PSA lamination technology, a transparent TSURF with an ultrahigh ultraviolet reduction rate of 99.5%, anti-wet abrasion resistance, and excellent self-cleaning performance was prepared. In addition, even after 12800 cycles of ethanol wet grinding and 300 hours of weather resistance test, the TSURF can still maintain superhydrophobicity and can cope with bending and twisting deformation, high and low temperature environment, and strong acid and alkali corrosion. The excellent adhesion of TSURF to various substrates provides a wide range of application choices. More notably, in the face of the development trend of green energy, TSURF is expected to be widely used on the surface of photovoltaic panels due to its excellent optical management and self-cleaning performance, to improve the photoelectric conversion efficiency, reduce labor costs and resource waste.

Claims

1. A stable and durable anti-UV super-hydrophobic material, comprising a stable and durable anti-UV super-hydrophobic film TSURF and a substrate, the stable and durable anti-UV super-hydrophobic film comprising a PMMA layer, a PET layer and a silicone pressure sensitive adhesive PSA layer in sequence, and the PSA layer of the stable and durable anti-UV super-hydrophobic film being adhered to the substrate; the PMMA layer containing nano-SiO 2, the nano-SiO 2 having a particle size of 5-10 nm; the PET film being a film modified by UV blocking; the stable and durable anti-UV super-hydrophobic film being obtained by hydrophobizing treatment on the surface, and the hydrophobizing treatment being completed by plasma gas etching using CHF 3 as working gas. The substrate is glass, stainless steel, acrylonitrile-butadiene-styrene plastic ABS, wood, leather or cloth. The total thickness of the stable and durable anti-UV super-hydrophobic film is 75-85 µm. The stable and durable anti-UV super-hydrophobic film has at least one of the following characteristics:

2. The stable and durable ultraviolet resistant superhydrophobic material according to claim 1, wherein, (1) having an average transmittance of more than 85% in the visible light region; 3. The stable and durable ultraviolet resistant superhydrophobic material according to claim 1, wherein, (2) in a test using anhydrous ethanol as wet grinding medium, the water contact angle on the surface of the stable and durable anti-UV super-hydrophobic film TSURF is still greater than 150° after 6400 cycles of grinding; 4. The stable and durable ultraviolet resistant superhydrophobic material according to claim 1, wherein, (3) after 12800 cycles of grinding using anhydrous ethanol as wet grinding medium, the water droplet contact angle hysteresis on the surface of the stable and durable anti-UV super-hydrophobic film TSURF is only 3.81°; (4) in air medium, the stable and durable anti-UV super-hydrophobic film TSURF can withstand 110 cycles of abrasion under a load of 100 g, and the contact angle is still greater than 150°. The adhesion of the stable and durable anti-UV super-hydrophobic film to the substrate is more than 10 MPa. 6.The stable and durable anti-UV super-hydrophobic material according to claim 5, wherein when the substrate is glass, the adhesion of the stable and durable anti-UV super-hydrophobic film to the substrate is 20.73 MPa; when the substrate is stainless steel, the adhesion of the stable and durable anti-UV super-hydrophobic film to the substrate is 18.44 MPa; when the substrate is acrylonitrile-butadiene-styrene plastic ABS, the adhesion of the stable and durable anti-UV super-hydrophobic film to the substrate is 15.26 MPa; when the substrate is polished wood, the adhesion of the stable and durable anti-UV super-hydrophobic film to the substrate is 14.93 MPa; and when the substrate is leather, the adhesion of the stable and durable anti-UV super-hydrophobic film to the substrate is 11.27 MPa. The preparation method of the stable and durable anti-UV super-hydrophobic film TSURF comprises the following steps:

5. The stable and durable ultraviolet resistant superhydrophobic material according to any one of claims 1-4, wherein, S1, pressing the silicone pressure sensitive adhesive PSA to the back side of the film with anti-UV property by a film press; S2, dissolving PMMA in acetone solvent, then adding nano-sized fumed hydrophobic SiO 2 and performing ultrasonic oscillation until complete dispersion; preparing SiO 2 mixed PMMA acetone solution, dropping and coating the SiO 2 mixed PMMA acetone solution to the surface side of the pressed PET film; ​ ​ ​ ​ 7. The stable and durable ultraviolet resistant superhydrophobic material according to any one of claims 1-4, wherein, ​ ​ ​ ​ S3, after acetone evaporation, a solid PMMA coating layer doped with SiO2 is formed on the PET film; S4, the surface is subjected to hydrophobization treatment to obtain a stable and durable ultraviolet resistant super-hydrophobic material TSURF; the plasma gas etching process is carried out in an inductively coupled plasma ICP etching system; CHF3 is used as a working gas for etching and fluorination of the film during the etching process to obtain a transparent super-hydrophobic film, wherein the fluorination etching treatment temperature is-5~5 ℃, and the treatment time is 15~25 s; the gas pressure during the etching process is set to 0.7~0.9 Pa, and the working flow rate is 0.05~0.07 L / min, wherein the upper electrode ICP power is set to 180~220 W, and the lower electrode RF power is set to 8~12 W.

8. The stable and durable ultraviolet resistant superhydrophobic material according to claim 7, wherein, In step S2, the mass fraction of PMMA is 10~20 wt%; In the PMMA layer preparation, the particle concentration in unit volume is (0.4-1)×10 -3 g·mL -1 , and the drop-coating solution volume per unit area is 0.05-0.20 mL·cm -2 .

9. Use of the stable and durable ultraviolet resistant super-hydrophobic material according to any one of claims 1-8 for photovoltaic materials.

Images