TWI898349B - A hydrophilic coating, preparation method and device - Google Patents

Abstract

Specific embodiments of the present invention provide a hydrophilic coating, preparation method, and device. The hydrophilic coating is formed on a substrate surface by hot-wire chemical vapor deposition of organosilicon monomers in an oxygen atmosphere. The hydrophilic coating exhibits excellent hydrophilic properties, with a water contact angle below 10°. Furthermore, the hydrophilic coating maintains excellent hydrophilicity in high-humidity environments.

Description

A hydrophilic coating, preparation method, and device

The present invention relates to the field of hot wire chemical vapor deposition, and in particular to a hot wire chemical vapor deposition hydrophilic coating, preparation method, and device.

This invention claims priority to Chinese patent application No. 2022116571892, filed with the China Patent Office on December 22, 2022, and entitled “A hydrophilic coating, preparation method and device,” the entire contents of which are incorporated herein by reference.

One of the most widely used methods for preparing hydrophilic coatings is to apply a hydrophilic polymer coating to a substrate surface. These hydrophilic polymer coatings typically contain a large number of hydrophilic groups (atomic or ionic groups capable of forming hydrogen bonds, such as -OH, -COOH, and -NH2), which impart hydrophilic and water-absorbing properties to the coating.

For example, a literature report states that a superhydrophilic surface can be obtained by reacting a uniform mixture of hydroxyethyl methacrylate, methacrylic acid, benzoyl peroxide, and ethylene glycol monoethyl ether at 65°C for 6-8 hours under nitrogen. The mixture is then diluted to a 10% concentration, and a small amount of ethylene glycol dimethacrylate and benzoyl peroxide are added. The mixture is then sprayed onto the substrate surface and allowed to dry at room temperature for 1-2 hours. Finally, the mixture is dried at 120°C for 1-2 hours and cooled to room temperature. However, superhydrophilic coatings prepared from these hydrophilic polymers have poor wear resistance and are extremely resistant to water immersion. In high humidity environments, the coating surface absorbs water, which easily increases the water contact angle, causing the coating to lose its superhydrophilic properties. The lack of water and moisture resistance of super-hydrophilic coatings greatly reduces their application in anti-fog and self-cleaning applications.

Specific embodiments of the present invention provide a hydrophilic coating, preparation method, and device with excellent hydrophilicity and excellent hydrophilicity retention in high-humidity environments. The specific scheme is as follows:

A hydrophilic coating having a water contact angle of less than 10° is provided. The hydrophilic coating is formed by depositing organosilicon monomers onto a substrate surface via hot-wire chemical vapor deposition in an oxygen atmosphere.

Optionally, the water contact angle of the hydrophilic coating is below 5°.

Optionally, the hydrophilic coating has a water contact angle of less than 10° after being immersed in water at room temperature for 120 minutes.

Optionally, the organic silicon monomer is selected from at least one of the structures in the following formulas (1) to (3).

In formulas (1) to (3), _R1 , _R5 , and _R9 are independently selected from _C1 - _C10 alkyl groups or C1- _C10 alkoxy groups; _R2 , _R3 , _R4 , _R6 , and _R10 are independently selected from hydrogen atom, _C1 - _C10 alkyl groups, or _C1 - _C10 alkoxy groups; _R7 is a hydrogen atom, a hydroxyl group, _{a C1} - _C10 alkyl group, or a _C1 - _C10 alkoxy group; _R8 is a hydrogen atom or a _C1 - _C10 alkyl group; n is an integer from 1 to 10; and m is an integer from 1 to 10.

Optionally, the organosilicon monomer has a structure represented by formula (1), and R ₁ , R ₂ , R ₃ and R ₄ are independently selected from C ₁ -C ₄ alkoxy groups.

Optionally, the organosilicon monomer is ethyl orthosilicate, tetramethoxysilane, propyl orthosilicate or butyl orthosilicate.

Optionally, the boiling point of the organosilicon monomer is below 200°C.

Optionally, the thickness of the hydrophilic coating is 5 to 3000 nm.

A method for preparing the hydrophilic coating as described above comprises the following steps:

Place the substrate on a sample stage with a cooling device in a vacuum deposition chamber;

The vacuum deposition chamber is evacuated, oxygen, inert gas, and organosilicon monomer gas are introduced, the heating wire is heated, and the cooling device is turned on to perform the hot wire chemical vapor deposition.

Optionally, the heating wire is a metal wire containing at least one of nickel, chromium or tungsten.

Optionally, the temperature of the sample stage is controlled below 100°C, and the temperature of the heating wire is 200-900°C.

Optionally, the method further includes the following step: performing plasma pre-treatment on the substrate surface before the hot-wire chemical vapor deposition.

Optionally, the method further includes the following step: after the hot wire chemical vapor deposition, performing plasma post-treatment on the surface of the hot wire chemical vapor deposition coating in an oxygen atmosphere.

Optionally, the plasma is a bi-electrode pulsed plasma.

A device, at least part of the surface of which has the hydrophilic coating as described above.

The hydrophilic coating of a specific embodiment of the present invention is formed on the substrate surface by hot-wire chemical vapor deposition of organosilicon monomers in an oxygen atmosphere. The hydrophilic coating has excellent hydrophilic properties, with a water contact angle of less than 10°. Furthermore, the hydrophilic coating maintains excellent hydrophilicity in high humidity environments.

Figure 1 shows the anti-fog test results of Example 1;

Figure 2 shows the anti-fog test results of Example 2;

Figure 3 shows the anti-fog test results of Example 3.

A specific embodiment of the present invention provides a hydrophilic coating having a water contact angle of less than 10°. The hydrophilic coating is formed by depositing an organosilicon monomer onto a substrate surface via hot-wire chemical vapor deposition in an oxygen atmosphere.

The hydrophilic coating of a specific embodiment of the present invention is deposited via hot-wire chemical vapor deposition. The organosilicon monomer, under oxygen atmosphere conditions and catalytic reaction of a heated metal hot wire, can form an excellent hydrophilic coating on the substrate surface. Furthermore, the hydrophilic coating exhibits excellent hydrophilic retention in high-humidity environments.

The water contact angle of the hydrophilic coating of a specific embodiment of the present invention is obtained by testing according to the GB/T 30447-2013 standard. In some specific embodiments, the water contact angle of the hydrophilic coating is less than 5°.

The hydrophilic coating of specific embodiments of the present invention has excellent hydrophilic retention in high-humidity environments. In some specific embodiments, the hydrophilic coating has a water contact angle of less than 10° after immersion in water at room temperature for 120 minutes. In some specific embodiments, the hydrophilic coating has a water contact angle of less than 5° after immersion in water at room temperature for 120 minutes.

The hydrophilic coating of a specific embodiment of the present invention has excellent hydrophilic retention in a high-humidity environment. In some specific embodiments, the water contact angle of the hydrophilic coating after immersion in water at room temperature for 10 minutes changes by no more than 30%. In some specific embodiments, the water contact angle of the hydrophilic coating after immersion in water at room temperature for 10 minutes changes by no more than 20%. In some specific embodiments, the water contact angle of the hydrophilic coating after immersion in water at room temperature for 10 minutes changes by no more than 10%. In some specific embodiments, the water contact angle of the hydrophilic coating after immersion in water at room temperature for 10 minutes changes by no more than 5%.

In some specific embodiments of the hydrophilic coating of the present invention, the organosilicon monomer has a structure shown in the following formula (1):

In formula (1), _R1 is selected from a _C1 - _C10 alkyl group or a _C1 - _C10 alkoxy group, and _R2 , _R3 , and _R4 are independently selected from a hydrogen atom, a _C1 - _C10 alkyl group, or a _C1 - _C10 alkoxy group. In some specific embodiments, _R1 is selected from a _C1 -C4 alkyl group or a _C1 - _C4 alkoxy group, and _R2 , _R3 , and _R4 are independently selected from a hydrogen atom, a _C1 - _C4 alkyl group, or a C1- _C4 alkoxy group. The _C1 - _C4 alkyl group is specifically exemplified _by a methyl group, an ethyl group, a propyl group, a butyl group, or an isobutyl group, or _{a C1} - _C4 alkoxy group is specifically exemplified by a _{methoxy group} , an ethoxy group, a propoxy group, a butoxy group, or an isobutoxy group. In some embodiments, R ₁ , R ₂ , R ₃ and R ₄ are independently selected from C ₁ -C ₄ alkoxy groups. In some embodiments, the organosilicon monomer is ethyl orthosilicate, tetramethoxysilane, propyl orthosilicate or butyl orthosilicate.

In some specific embodiments of the hydrophilic coating of the present invention, the organosilicon monomer has a structure shown in the following formula (2):

In formula (2), _R5 is selected from a _C1 - _C10 alkyl group or a _C1 - _C10 alkoxy group, _R6 is selected from a hydrogen atom, a _C1 - _C10 alkyl group or a _C1 - _C10 alkoxy group, _R7 is a hydrogen atom, a hydroxyl group, a _C1 - _C10 alkyl group or a _C1 - _C10 alkoxy group, _R8 is a hydrogen atom or a _C1 - _C10 alkyl group, and n is an integer from 1 to 10, specifically 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. In some embodiments, _R5 is selected from a _C1 - _C4 alkyl group or a _C1 - _C4 alkoxy group, _R6 is selected from a hydrogen atom, a _C1 - _C4 alkyl group or a _C1 - _C4 alkoxy group, R7 is a hydrogen atom, a hydroxyl group, a _C1 - _C4 alkyl group or a _C1 - _C4 alkoxy group, _{and R8} is a hydrogen atom or a C1- _{C4 alkyl} group, wherein the _C1 - _C4 alkyl group is exemplified by a methyl group, an ethyl group, a propyl group, a butyl group or an isobutyl group, or a _C1 - _C4 alkoxy group, wherein the _C1 - _C4 alkoxy group is exemplified by a methoxy group, an ethoxy group, a propoxy group, a butoxy group or an isobutoxy group.

In some specific embodiments of the hydrophilic coating of the present invention, the organosilicon monomer has a structure shown in the following formula (3):

In formula (3), _R9 is selected from _C1 - _C10 alkyl or _C1 - _C10 alkoxy, _R10 is selected from hydrogen, _C1 - _C10 alkyl or C1- _C10 alkoxy, and m is an integer from 1 to ₁₀ , specifically 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. In some embodiments, _R9 is selected from a _C1 - _C4 alkyl group or a _C1 - _C4 alkoxy group, and _R10 is selected from a hydrogen atom, a _C1 - _C4 alkyl group or a _C1 - _C4 alkoxy group, wherein _{the C1-C4 alkyl} group is exemplified by a methyl group, an ethyl group, a propyl group, a butyl group or an isobutyl group, or a _C1 - _C4 alkoxy group, wherein the _C1 - _C4 alkoxy group is exemplified by a methoxy group, an ethoxy group, a propoxy group, a butoxy group or an isobutoxy group.

In order to facilitate the evaporation and vaporization of the organosilicon monomer, the hydrophilic coating of the specific embodiment of the present invention, in some specific embodiments, the boiling point of the organosilicon monomer is below 200°C.

In specific embodiments of the present invention, the hydrophilic coating has a thickness on the nanometer scale. In some specific embodiments, the coating has a thickness of 1 to 3000 nm, in some specific embodiments, the coating has a thickness of 5 to 500 nm, and in some specific embodiments, the coating has a thickness of 5 to 150 nm.

In some embodiments of the hydrophilic coating of the present invention, the substrate is metal, ceramic, plastic, glass, electronic equipment, or optical instruments. In some embodiments, the substrate is a transparent material, such as lenses for glasses, goggles, laser protection lenses, telescopes and lenses for various photographic equipment, observation windows for various machines, sports goggles, bathroom glass, chemical or biological protective masks, vehicle windshields and rearview mirrors, explosives disposal equipment, helmets, solar panels, observation windows for measuring instruments, glass covers, and greenhouse glass walls.

A specific embodiment of the present invention also provides a method for preparing the hydrophilic coating as described above, comprising the following steps:

Place the substrate on a sample stage with a cooling device in a vacuum deposition chamber;

The vacuum deposition chamber is evacuated, oxygen, inert gas, and organosilicon monomer gas are introduced, the heating wire is heated, and the cooling device is turned on to perform the hot wire chemical vapor deposition.

In some embodiments of the present invention, the method for preparing a hydrophilic coating comprises a metal wire containing at least one of nickel, chromium, or tungsten. Specifically, the heating wire may be a nickel wire, a chromium wire, a tungsten wire, a nickel-chromium wire, or a nickel-tungsten wire.

In some embodiments of the method for preparing a hydrophilic coating according to the present invention, the temperature of the sample stage is controlled below 100°C. In some embodiments, the temperature of the sample stage is controlled between 20°C and 50°C, specifically, 20°C, 30°C, 40°C, or 50°C. In some embodiments, the sample stage is cooled by water.

In some embodiments of the present invention, the temperature of the heating wire is between 200°C and 900°C, and specifically, it can be 200°C, 250°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, or 900°C.

In the method for preparing a hydrophilic coating according to a specific embodiment of the present invention, the vacuum level of the vacuum deposition chamber can be set according to actual conditions. In some specific embodiments, the vacuum level is 0.1 to 1000 mTorr, in some specific embodiments, the vacuum level is 1 to 100 mTorr, and in some specific embodiments, the vacuum level is 5 to 50 mTorr.

In the method for preparing a hydrophilic coating according to a specific embodiment of the present invention, the inert gas includes nitrogen, helium, neon, or argon. In some specific embodiments, the flow rate of the inert gas is 0 to 1000 sccm, in some specific embodiments, the flow rate of the inert gas is 5 to 500 sccm, and in some specific embodiments, the flow rate of the inert gas is 50 to 200 sccm.

In the method for preparing a hydrophilic coating according to a specific embodiment of the present invention, in some specific embodiments, the flow rate of the inert gas is 1 to 1000 sccm, in some specific embodiments, the flow rate of the inert gas is 5 to 500 sccm, and in some specific embodiments, the flow rate of the inert gas is 50 to 200 sccm.

The preparation method of the hydrophilic coating of the specific embodiment of the present invention, in some specific embodiments, the preparation method of the hydrophilic coating further includes the following steps: before the hot wire chemical vapor deposition, the surface of the substrate is subjected to plasma pre-treatment. In some specific embodiments, the plasma is a bipolar pulsed plasma. Through the plasma pre-treatment, the hydrophilicity of the hydrophilic coating and the hydrophilicity retention in a high humidity environment can be further effectively improved. In some specific embodiments, the hydrophilic coating is subjected to plasma pre-treatment. In an embodiment, the pulsed plasma has a discharge power of 10 to 1000 W, a discharge time of 10 to 1000 s, a pulse frequency of 1 to 1000 Hz, and a pulse duty cycle of 1:1 to 1:500. In some specific embodiments, the pulsed plasma has a discharge power of 100 to 500 W, a discharge time of 100 to 500 s, a pulse frequency of 10 to 500 Hz, and a pulse duty cycle of 1:10 to 1:100.

In the method for preparing a hydrophilic coating according to a specific embodiment of the present invention, in some specific embodiments, the plasma pre-treatment is performed in an atmosphere containing oxygen, in some specific embodiments, the plasma pre-treatment is performed in an atmosphere containing an inert gas, and in some specific embodiments, the plasma pre-treatment is performed in an atmosphere containing oxygen and an inert gas.

The preparation method of the hydrophilic coating of the specific embodiment of the present invention, in some specific embodiments, the preparation method of the hydrophilic coating further includes the following steps: after the hot wire chemical vapor deposition, in an oxygen atmosphere, the surface of the coating of the hot wire chemical vapor deposition is subjected to plasma post-treatment. In some specific embodiments, the plasma is a bipolar pulsed plasma. Through the plasma post-treatment, the hydrophilicity of the hydrophilic coating and the hydrophilicity in a high humidity environment can be further effectively improved. Water retention. In some specific embodiments, the pulsed plasma has a discharge power of 10-1000 W, a discharge time of 1-1000 s, a pulse frequency of 1 to 1000 Hz, and a pulse duty cycle of 1:1 to 1:500. In some specific embodiments, the pulsed plasma has a discharge power of 100-500 W, a discharge time of 10-500 s, a pulse frequency of 10 to 500 Hz, and a pulse duty cycle of 1:10 to 1:100.

In some embodiments of the method for preparing a hydrophilic coating according to the present invention, a pair or more copper electrodes are installed in the vacuum deposition chamber. Before and after the hot-wire chemical vapor deposition, the copper electrodes are turned on, and the plasma pre-treatment and plasma post-treatment processes are performed directly in the vacuum deposition chamber.

In some embodiments of the present invention, the method for preparing a hydrophilic coating comprises: in some embodiments, the organosilicon monomer enters a vaporization chamber for vaporization and is then introduced into the vacuum deposition chamber. In some embodiments, the organosilicon monomer enters the vaporization chamber at a certain flow rate; in some embodiments, the organosilicon monomer enters the vaporization chamber in multiple batches; in some embodiments, the flow rate of the organosilicon monomer entering the vaporization chamber is 10-2400 μL/min; and in some embodiments, the flow rate of the organosilicon monomer entering the vaporization chamber is 100-500 μL/min.

The method for preparing a hydrophilic coating according to a specific embodiment of the present invention includes the hydrophilic coating, organosilicon monomer, and substrate as described above.

Specific embodiments of the present invention further provide a device, wherein at least a portion of the surface of the device has the aforementioned hydrophilic coating. In some specific embodiments, the aforementioned hydrophilic coating is deposited on a portion or the entire surface of the device.

The present invention is further described below through specific examples.

Implementation Examples

Test method description

Coating thickness test: Testing was performed using the American Filmetrics F20-UV film thickness meter.

Water contact angle test: Tested in accordance with GB/T 30447-2013.

Anti-fogging test: Place the glass plate sample in a 95°C constant temperature water bath with the coated surface facing the water vapor. The distance between the water surface and the coated surface is 5 cm. Observe for fogging after 10 minutes.

Example 1

A transparent glass plate (length: 13 cm, width: 6.5 cm, thickness: 1 mm) and a silicon wafer were placed on the sample stage of a vacuum deposition chamber equipped with a pair of copper rod electrodes. The chamber was evacuated to a vacuum of 8 mTorr, and the sample stage temperature was controlled at approximately 30°C using water cooling. Helium and oxygen were introduced simultaneously at a flow rate of 90 sccm each, and the chamber pressure was maintained at 100 mTorr.

Turn on the copper rod electrode pulsed plasma discharge to pre-treat the transparent glass surface. The discharge time is 240 seconds and the discharge power is 400W.

The copper rod electrode plasma discharge was turned off, and the nickel-chromium hot filament power supply was turned on, with the hot filament temperature controlled at 300°C. Tetraethyl orthosilicate (TEOS) was vaporized at 110°C and introduced into the vacuum deposition chamber at a flow rate of 300 μl/min. Meanwhile, the water-cooled sample stage temperature, chamber pressure, and helium and oxygen flow rates were maintained constant.

After coating, the temperature and vacuum were maintained constant. After 30 minutes, the vacuum was broken and the silicon wafer and glass plate samples were removed. The coating thickness of the silicon wafer was tested, and the water contact angle test results of the glass plate samples were listed in Table 1 below. At room temperature, the glass plate samples were immersed in water for different times and then naturally dried. The water contact angle test results are listed in Table 2 below. The anti-fog test results of the coated (coated) glass plate samples and the uncoated blank glass plate samples are shown in Figure 1.

Example 2

A transparent glass plate (length: 13 cm, width: 6.5 cm, thickness: 1 mm) and a silicon wafer were placed on the sample stage of a vacuum deposition chamber equipped with a pair of copper rod electrodes. The chamber was evacuated to a vacuum of 8 mTorr, and the sample stage temperature was controlled at approximately 30°C using water cooling. Helium and oxygen were introduced simultaneously at a flow rate of 90 sccm each, and the chamber pressure was maintained at 100 mTorr.

Turn on the nickel-chromium hot wire power supply and control the hot wire temperature to 300°C. After vaporizing tetraethyl orthosilicate (TEOS) at 110°C, introduce it into the vacuum deposition chamber at a flow rate of 300 μl/min. Simultaneously, maintain the water-cooled sample stage temperature, chamber pressure, and helium and oxygen flow rates constant.

After coating, the temperature and vacuum were maintained constant. After 30 minutes, the vacuum was broken and the silicon wafer and glass plate samples were removed. The coating thickness of the silicon wafer was tested, and the water contact angle test results of the glass plate samples were listed in Table 1 below. At room temperature, the glass plate samples were immersed in water for different times and then naturally dried. The water contact angle test results are listed in Table 2 below. The anti-fog test results of the coated (coated) glass plate samples and the uncoated blank glass plate samples are shown in Figure 2.

Example 3

A transparent glass plate (length: 13 cm, width: 6.5 cm, thickness: 1 mm) and a silicon wafer were placed on the sample stage of a vacuum deposition chamber equipped with a pair of copper rod electrodes. The chamber was evacuated to a vacuum of 8 mTorr, and the sample stage temperature was controlled at approximately 30°C using water cooling. Helium and oxygen were introduced simultaneously at a flow rate of 90 sccm each, and the chamber pressure was maintained at 100 mTorr.

Turn on the copper rod electrode pulsed plasma discharge to pre-treat the transparent glass surface. The discharge time is 240 seconds and the discharge power is 400W.

Turn off the copper rod electrode plasma discharge, turn on the nickel-chromium hot wire power supply, and control the hot wire temperature to 300°C. After vaporizing tetraethyl orthosilicate (TEOS) at 110°C, introduce it into the vacuum deposition chamber at a flow rate of 300μl/min. At the same time, maintain the water-cooled sample stage temperature, chamber pressure, and helium and oxygen flow rates constant.

Turn off the power to the nickel-chromium heating wire, shut off the helium flow, maintain the oxygen flow at 90 sccm, and maintain the chamber pressure at 100 mTorr. Restart the copper rod electrode pulsed plasma discharge, with a discharge time of 30 seconds and a discharge power of 300 W.

After coating, the temperature and vacuum were maintained constant. After 30 minutes, the vacuum was broken and the silicon wafer and glass plate samples were removed. The coating thickness of the silicon wafer was tested, and the water contact angle test results of the glass plate samples were listed in Table 1 below. At room temperature, the glass plate samples were immersed in water for different times and then naturally dried. The water contact angle test results are listed in Table 2 below. The anti-fog test results of the coated (coated) glass plate samples and the uncoated blank glass plate samples are shown in Figure 3.

Comparative Example 1

A transparent glass plate (length: 13 cm, width: 6.5 cm, thickness: 1 mm) and a silicon wafer were placed in a plasma enhanced chemical vapor deposition (PECVD) vacuum reaction chamber. The chamber was continuously evacuated to a vacuum level of 80 mTorr. The chamber temperature was maintained at 45°C, and helium was introduced at a flow rate of 40 sccm.

Maintain the chamber pressure at 80 mTorr and the helium flow rate at 40 sccm. Start RF plasma discharge to pre-treat the surface of the transparent glass plate. The RF energy output mode is continuous discharge, with a discharge time of 300 seconds and a discharge power of 300W.

Then, 1,4-butenediol was introduced at a monomer flow rate of 120 μL/min and a monomer vaporization temperature of 110°C. The chamber pressure was maintained at 80 mTorr, the helium flow rate was maintained at 40 sccm, and RF plasma discharge was initiated. The RF energy output mode was pulsed, with a discharge time of 5400 s, a discharge power of 80 W, a pulse frequency of 50 Hz, and a pulse duty cycle of 45%.

After the coating preparation was completed, the reaction chamber was returned to normal pressure. The chamber was opened to remove the silicon wafer and glass plate samples. The coating thickness of the silicon wafer was tested, and the water contact angle of the glass plate samples was tested. The results are listed in Table 1 below. At room temperature, the glass plate samples were immersed in water for different times and then naturally dried. The water contact angle test results are listed in Table 2 below.

Comparative Example 2

A transparent glass plate (length: 13 cm, width: 6.5 cm, thickness: 1 mm) and a silicon wafer were placed in a PECVD vacuum reaction chamber. The chamber was continuously evacuated to a vacuum level of 80 mTorr. The chamber temperature was maintained at 45°C, and helium was introduced at a flow rate of 40 sccm.

Maintain the chamber pressure at 80 mTorr and the helium flow rate at 40 sccm. Start RF plasma discharge to pre-treat the surface of the transparent glass plate. The RF energy output mode is continuous discharge, with a discharge time of 300 seconds and a discharge power of 300W.

Next, 1,4-butenediol and methacrylamide were mixed in a mass ratio of 5:1 and stirred at room temperature for 10 minutes until uniformly mixed. The mixture was then passed through a vaporization chamber for vaporization and then introduced into the PECVD vacuum reaction chamber. The monomer flow rate into the vaporization chamber was 120 μL/min, the monomer vaporization temperature was 110°C, the chamber pressure was maintained at 80 mTorr, the helium flow rate was maintained at 40 sccm, and the RF plasma discharge was started. The RF energy output mode was pulsed, with a discharge time of 1800 s, a discharge power of 80 W, a pulse frequency of 50 Hz, and a pulse duty cycle of 45%.

After the coating preparation was completed, the reaction chamber was returned to normal pressure. The chamber was opened to remove the silicon wafer and glass plate samples. The coating thickness of the silicon wafer was tested, and the water contact angle of the glass plate samples was tested. The results are listed in Table 1 below. At room temperature, the glass plate samples were immersed in water for different times and then naturally dried. The water contact angle test results are listed in Table 2 below.

Comparative Example 3

A transparent glass plate (length: 13 cm, width: 6.5 cm, thickness: 1 mm) and a silicon wafer were placed in a PECVD vacuum reaction chamber. The chamber was continuously evacuated to a vacuum level of 80 mTorr. The chamber temperature was maintained at 45°C, and helium was introduced at a flow rate of 40 sccm.

Then, tetraethyl orthosilicate (TEOS) was introduced at a monomer flow rate of 45 μL/min and a monomer vaporization temperature of 110°C. The chamber pressure was maintained at 80 mTorr, the helium flow rate was maintained at 40 sccm, and the RF plasma discharge was started. The RF energy output mode was pulsed, with a discharge time of 3600 s, a discharge power of 80 W, a pulse frequency of 50 Hz, and a pulse duty cycle of 45%.

After the coating preparation was completed, the reaction chamber was returned to normal pressure. The chamber was opened to remove the silicon wafer and glass plate samples. The coating thickness of the silicon wafer was tested, and the water contact angle of the glass plate samples was tested. The results are listed in Table 1 below. At room temperature, the glass plate samples were immersed in water for different times and then naturally dried. The water contact angle test results are listed in Table 2 below.

Comparative Example 4

A transparent glass plate (length: 13 cm, width: 6.5 cm, thickness: 1 mm) and a silicon wafer were placed on the sample stage of a vacuum deposition chamber equipped with a pair of copper rod electrodes. The chamber was evacuated to a vacuum of 8 mTorr, and the sample stage temperature was controlled at approximately 30°C using water cooling. Helium was introduced at a flow rate of 90 sccm, and the chamber pressure was maintained at 100 mTorr.

Turn on the nickel-chromium hot wire power supply and control the hot wire temperature to 300°C. After vaporizing tetraethyl orthosilicate (TEOS) at 110°C, introduce it into the vacuum deposition chamber at a flow rate of 300 μl/min. Simultaneously, maintain the water-cooled sample stage temperature, chamber pressure, and helium and oxygen flow rates constant.

After coating, the temperature and vacuum were maintained constant. After 30 minutes, the vacuum was broken and the silicon wafer and glass plate samples were removed. The coating thickness of the silicon wafer was tested, and the water contact angle of the glass plate samples was tested. The results are listed in Table 1 below. At room temperature, the glass plate samples were immersed in water for different times and then naturally dried. The water contact angle test results are listed in Table 2 below.

According to the results in Tables 1 and 2 above, in Examples 1-3, the hydrophilic coating formed by hot-wire chemical vapor deposition of the organosilicon monomer ethyl orthosilicate on the substrate surface in an oxygen atmosphere has excellent hydrophilic properties, with a water contact angle of less than 5°. Moreover, the water contact angle of the coating can still be maintained below 10° after being immersed in water for 180 minutes, indicating that it has excellent hydrophilic retention in a high humidity environment. In Comparative Examples 1-2, the hydrophilic monomer is used to form the coating by plasma polymerization. Although a coating with excellent hydrophilic properties can be obtained, its hydrophilicity significantly decreases after immersion in water for 10 minutes, indicating poor hydrophilicity retention in high-humidity environments. In Comparative Example 3, the plasma-polymerized coating or coating of ethyl orthosilicate exhibited a water contact angle of 95°, indicating a lack of hydrophilicity. In Comparative Example 4, the hot-wire chemical vapor deposition of ethyl orthosilicate without oxygen resulted in a water contact angle of 20°, indicating poor hydrophilicity. Comparing the results of Examples 1-3, in Example 3, the glass plate with a plasma pre-treatment step and a plasma post-treatment step in an oxygen atmosphere has a better hydrophilicity retention in a high humidity environment than the glass plate with only a plasma pre-treatment step in Example 1. The hydrophilicity and hydrophilicity of the glass plate sample with only a plasma pre-treatment step in a high humidity environment are better than those of the glass plate sample with only a plasma pre-treatment step in a high humidity environment. The hydrophilicity retention of the glass plate samples in Example 2, which did not undergo the plasma pre-treatment and post-treatment steps, is superior to that of the glass plate samples in Example 2. This indicates that the plasma pre-treatment step is beneficial for improving the hydrophilicity of the coating and its hydrophilicity retention in a high-humidity environment. The plasma post-treatment step in an oxygen atmosphere further improves the hydrophilicity retention of the coating in a high-humidity environment. The results in Figures 1-3 demonstrate that the coatings in Examples 1-3 have excellent anti-fogging properties.

Although the present invention is disclosed above, it is not limited thereto. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims.

Claims (15)

A hydrophilic coating is characterized in that the water contact angle of the hydrophilic coating is less than 10 degrees. The hydrophilic coating is formed by hot-wire chemical vapor deposition of organosilicon monomers on the surface of a substrate in an oxygen atmosphere. The hydrophilic coating according to claim 1, wherein the water contact angle of the hydrophilic coating is less than 5°. The hydrophilic coating according to claim 1, wherein the water contact angle of the hydrophilic coating after being immersed in water at room temperature for 120 minutes is less than 10°. The hydrophilic coating according to claim 1, wherein the organosilicon monomer is selected from at least one of the structures of the following formulae (1) to (3): (1) (2) (3) In the above formulas (1) to (3), _R1 , _R5 and _R9 are independently selected from _C1 - _C10 alkyl groups or _C1 - _C10 alkoxy groups, _R2 , _R3 , _R4 , _R6 and _R10 are independently selected from hydrogen atom, _C1 - _C10 alkyl groups or C1- _C10 alkoxy groups, _R7 is a hydrogen atom, a hydroxyl group, _C1 - _C10 alkyl groups or _C1 - _C10 alkoxy groups, _R8 is a hydrogen atom or _C1 - _C10 alkyl groups, n is an integer from 1 to 10 _, and m is an integer from 1 to 10. The hydrophilic coating according to claim 1, wherein the organosilicon monomer has a structure represented by formula (1), and R ₁ , R ₂ , R ₃ and R ₄ are independently selected from C ₁ -C ₄ alkoxy groups. The hydrophilic coating according to claim 5, wherein the organosilicon monomer is ethyl orthosilicate, tetramethoxysilane, propyl orthosilicate, or butyl orthosilicate. The hydrophilic coating according to claim 1, wherein the boiling point of the organosilicon monomer is below 200°C. The hydrophilic coating according to claim 1, wherein the thickness of the hydrophilic coating is 5 nm to 3000 nm. A method for preparing a hydrophilic coating as described in any one of claims 1 to 8, comprising the following steps: Placing a substrate on a sample stage equipped with a cooling device in a vacuum deposition chamber; Evacuating the vacuum deposition chamber, introducing oxygen, an inert gas, and an organosilicon monomer gas, and performing the hot-wire chemical vapor deposition by activating the heating wire and the cooling device. The method for preparing a hydrophilic coating as described in claim 9, wherein the heating wire is a metal wire containing at least one of nickel, chromium or tungsten. The method for preparing a hydrophilic coating as described in claim 9, wherein the temperature of the sample stage is controlled below 100°C and the temperature of the heating wire is 200-900°C. The method for preparing a hydrophilic coating as described in claim 9 further includes the following step: performing plasma pre-treatment on the surface of the substrate before the hot wire chemical vapor deposition. The method for preparing a hydrophilic coating as described in claim 9 further comprises the following step: after the hot wire chemical vapor deposition, the surface of the hot wire chemical vapor deposition coating is subjected to plasma post-treatment in an oxygen atmosphere. The method for preparing a hydrophilic coating as described in claim 12 or 13, wherein the plasma is a bipolar pulsed plasma. A device, characterized in that at least a portion of its surface has the hydrophilic coating according to any one of claims 1 to 8.