Preparation method of super-hydrophilic surface with ordered microstructure construction and coating thereof

Abstract

The application relates to a preparation method of an ordered microstructure constructed super-hydrophilic surface and a coating thereof, and belongs to the technical field of surface functionalized coating preparation. The method comprises the following steps: depositing an HMDSO polymer on the surface of a substrate by PECVD to form an initial organic silicon deposition layer; then, the ventilation and plasma are closed and a time interval is set to control the surface active group density; a TMCTS polymer is deposited on the obtained organic layer surface, so that the fragment structure formed after TMCTS plasma activation is preferentially deposited on the surface active sites to form an ordered cell microstructure; and the surface with the microstructure is subjected to oxygen plasma modification and hydrophilic polymer molecule grafting to construct a super-hydrophilic functional layer. The application realizes the ordered construction of the surface microstructure by synergistically controlling the precursor chemical properties, active sites and local selective growth, and obtains a coating with high light transmittance, long-term stable super-hydrophilicity and excellent anti-fog performance through acrylic acid grafting.

Description

Technical Field

[0001] This invention belongs to the technical field of surface functionalized coating preparation, specifically relating to a method for preparing a superhydrophilic surface with an ordered microstructure and its coating. Background Technology

[0002] Transparent anti-fog coatings are widely used in optical lenses, automotive windows, cameras, and optical components for aerospace equipment, especially in environments with high humidity and large temperature differences, such as automotive windshields, electronic device displays, and aviation instruments. The main function of superhydrophilic anti-fog coatings is to reduce the surface contact angle, promote the spread of water film, prevent water droplets from forming on the surface, and avoid visual blurring caused by light scattering.

[0003] However, while traditional superhydrophilic coatings can effectively eliminate surface droplets in the initial stage, they have significant limitations in long-term use. These coatings typically rely on hydrophilic groups (such as -OH and -COOH) introduced to the surface to achieve superhydrophilicity, but these groups are easily oxidized, adsorb impurities from the air, or chemically degraded over time, leading to a gradual decline in coating performance and difficulty in maintaining the anti-fogging effect in the long term. Especially for smooth, unstructured superhydrophilic surfaces, the wetting and spreading process of water droplets upon contact with the surface is mainly dominated by surface chemistry, lacking effective regulation of the liquid interface by surface structure. When surface hydrophilic groups are contaminated or locally fail, water droplets shrink locally, making it difficult to form a continuous and stable water film. Such superhydrophilic surfaces, relying solely on chemical composition and lacking structural synergy, struggle to maintain a stable superhydrophilic state in complex environments.

[0004] Constructing micro- and nano-structures on surfaces can create more capillary channels and continuous spreading paths, accelerating the transformation of water droplets into water films. Simultaneously, the microstructures have a pinning effect on the liquid interface, making the formed water film less prone to rupture or retraction when disturbed, effectively enhancing the stability of water film spreading. However, the large height fluctuations and scale distribution differences of disordered microstructures introduce light scattering effects, leading to decreased transmittance and making it difficult to meet the high transparency requirements of optical devices. Compared to disordered microstructures, ordered microstructures have regular arrangements and specific spatial frequencies, reducing the randomness of surface morphology and effectively avoiding multi-angle scattering and increased haze caused by random height fluctuations and scale distribution, maintaining the high transparency of the material. Furthermore, ordered microstructures can form a refractive index gradient layer between the air and the substrate, reducing light reflection loss at the interface, thereby improving transmittance while ensuring low scattering. Therefore, ordered microstructure surfaces not only do not reduce transmittance but also help improve overall optical performance, providing a structural basis for their application in transparent anti-fog coatings and optical devices, and promising more stable and durable anti-fog surfaces.

[0005] However, existing methods for constructing ordered microstructured surfaces still have certain limitations. While top-down processing techniques such as photolithography and template methods can achieve regular structures, the processes are complex and costly, with limited adaptability to substrate size and morphology. Furthermore, the structures rely on physical forming, and the lack of strong chemical bonds between the structural layers and the substrate makes them susceptible to structural damage under mechanical wear or environmental stress, hindering large-scale applications. Meanwhile, bottom-up methods such as spraying and dip coating are simple and widely applicable, but the film formation process is affected by factors such as droplet accumulation and solvent evaporation, resulting in highly random structural growth and making it difficult to achieve ordered microstructure control, especially in actual production where it is difficult to form coatings with high transparency.

[0006] Chemical vapor deposition (CVD) offers advantages in constructing stable functional coatings due to its solvent-free process, uniform film formation, and ability to form chemical bonds with the substrate. However, traditional single-step CVD processes often focus on growing continuous films, lacking precise control over surface morphology and structural evolution. This makes it difficult to construct superhydrophilic surfaces with ordered microstructures while maintaining high transparency. Therefore, it is of great significance to prepare coatings with high transparency, strong adhesion, controllable microstructure, and the ability to maintain superhydrophilic anti-fogging effects during long-term use. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems existing in the prior art and provide a superhydrophilic surface coating constructed with an ordered microstructure and its preparation method. This invention is achieved through the following technical solution: This invention provides a superhydrophilic surface coating constructed with an ordered microstructure, wherein the coating comprises, from the substrate outwards: An initial organosilicon smoothing layer containing Si-O-Si / Si-OH bonds was deposited on the substrate surface using PECVD with HMDSO and O2 as reactant gases. An ordered cellular or island-like microstructure layer is formed on the initial smooth silicone layer. This microstructure layer is composed of a silicone polymer containing Si-O-Si bonds, and the microstructure unit size is 0.3-1.2 μm. These microstructure units are orderly arranged and distributed on the initial smooth silicone layer. A hydrophilic polymer layer is chemically bonded to the surface of the microstructure layer.

[0008] Furthermore, the hydrophilic polymer layer is an acrylic polymer hydrophilic layer, in which the carboxyl groups (-COOH) in the acrylic polymer hydrophilic layer are bonded to water molecules through hydrogen bonds, giving the coating superhydrophilic properties.

[0009] Furthermore, the thickness of the acrylic polymer hydrophilic layer is 5-50 nm, and the hydrophilic layer is treated with PECVD to form a stable network with a cross-linked structure.

[0010] Another aspect of the present invention provides a method for preparing a superhydrophilic surface constructed with an ordered microstructure, comprising the following steps: (1) Using PECVD, HMDSO and O2 are used as reaction gases to form an initial organosilicon deposition layer containing Si–O–Si / Si–OH on the substrate surface; (2) After deposition in step (1), stop the flow of reaction gas and turn off the plasma power supply, and keep the substrate in a vacuum environment for 1 min-3 min to regulate the density of surface active groups; (3) PECVD deposition is performed on the surface after treatment in step (2) using TMCTS and O2 as reaction gases under the condition of plasma power of 100-200W, so that the fragment structure formed after TMCTS plasma activation is preferentially deposited at the surface active site to form an ordered cellular microstructure.

[0011] (4) The surface with microstructure obtained in step (3) is activated by oxygen plasma and hydrophilic polymer monomers are introduced for plasma grafting polymerization to construct a superhydrophilic functional layer.

[0012] Furthermore, in step (2), the sample is left to stand in a vacuum environment for 2 minutes.

[0013] Further, in step (1), the HMDSO to O2 flow rate ratio is 2:1, the deposition pressure is 40-70 Pa, and the deposition time is 2-5 min.

[0014] Furthermore, in step (3), the TMCTS to O2 flow rate ratio is 1:1, the deposition pressure is 40-80 Pa, and the deposition time is 5-15 min.

[0015] Furthermore, the hydrophilic polymer monomer in step (4) is acrylic acid.

[0016] Further, the construction of the superhydrophilic functional layer in step (4) specifically includes: first, introducing O2 into the cavity for plasma activation treatment; then introducing a mixed gas of acrylic acid and O2, and performing graft polymerization under discharge conditions; finally, turning off O2 and continuously introducing acrylic acid gas for subsequent reactions; the ratio of the mixed gas of acrylic acid and O2 is 2:1, and the graft polymerization temperature is 50-80℃, and the time is 10-20min.

[0017] Furthermore, in step (1), the substrate includes any one of silicon wafer, glass, ceramic, metal, and plastic.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention uses PECVD technology to obtain an ordered planar microstructure, which can ensure the transparency of the coating, while also meeting certain surface roughness requirements and increasing the specific surface area of ​​the coating. Furthermore, the anti-fogging effect is improved by adjusting wetting kinetics and enhancing the water film spreading ability.

[0019] (2) This invention uses plasma to pretreat a substrate with an ordered microstructure, which can generate active groups such as hydroxyl groups on the substrate surface and also clean the substrate surface to remove residual organic fragments. The generated active groups can serve as grafting sites, providing more grafting sites for the next grafting step.

[0020] (3) The present invention prepares ordered microstructures by PECVD technology, which can obtain a surface with visible light transmittance of more than 98%; after further modification by oxygen plasma and hydrophilic flexible polymer molecular linking, the static contact angle of the surface can be reduced to less than 5 degrees and the superhydrophilicity can be maintained for more than 70 days. Attached Figure Description

[0021] Figure 1 This is a planar schematic diagram of the surface morphology of the substrate with ordered microstructure obtained in Example 1; Figure 2 This is a schematic cross-sectional view of the surface morphology of the substrate with ordered microstructure obtained in Example 1; Figure 3 The water contact angle of the ordered microstructure grafted superhydrophilic coating in Example 1; Figure 4 This is a schematic diagram of the surface morphology of the sample in Example 3 with the deposition time changed to 5 min. Figure 5 This is a schematic diagram of the surface morphology of the sample in Example 4 with the deposition time changed to 15 min. Figure 6 This is a schematic diagram of the surface morphology of the sample with interchanged monomers and other conditions remaining unchanged in Comparative Example 2. Figure 7 This is a schematic diagram of the surface morphology of the sample in Comparative Example 4 without steps (1) and (3) at a 2-minute interval. Figure 8 For Comparative Example 5, the sample surface morphology planar diagram with the interval between steps (1) and (3) changed from 2 min to 5 min is shown. Figure 9 For Comparative Example 7, a schematic diagram of the sample surface morphology with the deposition power changed to 100W in step (3) is shown. Figure 10 For Comparative Example 8, the deposition power in step (3) was changed to 200W, and a schematic diagram of the sample surface morphology was obtained. Figure 11For Comparative Example 9, a schematic diagram of the surface morphology of a sample with the gas ratio changed from TMCTS:O2=7:3 in step (2) is shown. Figure 12 For Comparative Example 10, a schematic diagram of the surface morphology of a sample with the gas ratio changed from TMCTS:O2=3:7 in step (3) is shown. Figure 13 The image shows a comparison of the anti-fog test results of Example 1, Comparative Example 1, and an untreated glass slide under 80°C water vapor on the first day. In the image, a represents Example 1, b represents Comparative Example 1, and c represents the untreated glass slide. Figure 14 The image shows a comparison of the anti-fogging test results of Example 1, Comparative Example 1, and an untreated glass slide under 80°C water vapor on the fourth day. In the image, a represents Example 1, b represents Comparative Example 1, and c represents the untreated glass slide. Figure 15 The image shows a comparison of the anti-fogging test results of Example 1, Comparative Example 1, and an untreated glass slide under 80°C water vapor on the seventh day. In the image, a represents Example 1, b represents Comparative Example 1, and c represents the untreated glass slide. Detailed Implementation

[0022] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0023] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0024] This invention provides a method for preparing superhydrophilic surfaces with ordered microstructures. The core of this method lies in achieving a transformation of the surface micromorphology from "disordered growth" to "ordered anchoring" through stepwise control during the PECVD process, and combining this with chemical grafting to enhance longevity. This method is applicable to various substrate materials, including but not limited to silicon wafers, glass, ceramics, metals, and plastics.

[0025] Step (1): Construction of the initial organosilicon deposition layer

[0026] Using PECVD with HMDSO (hexamethyldisiloxane) and O2 as reactants, an initial organosilicon deposition layer containing Si–O–Si / Si–OH was formed on the substrate surface. This layer not only serves as the base layer for subsequent microstructure growth but also provides the active sites required for chemical bonding.

[0027] In this step, the preferred flow ratio of HMDSO to O2 is 2:1, the deposition pressure is controlled within the range of 40-70 Pa, and the deposition time is 2-5 min. The plasma power is a key parameter affecting the degree of precursor dissociation and deposition quality; this invention controls it within the range of 100-200 W, preferably 120-150 W. When the power is below 100 W, the degree of HMDSO dissociation is insufficient, the concentration of active fragments is low, the deposition rate is slow, and the film quality is poor, making it difficult to form a dense and uniform organosilicon layer. When the power is above 200 W, excessive plasma energy causes partial etching of the deposit, and high-energy particle bombardment may damage the substrate surface. Within the preferred range of 100-200 W, HMDSO can fully dissociate and form a smooth organosilicon layer rich in Si–O–Si framework and Si–OH active groups on the substrate surface; the thickness of this layer is typically 20-30 nm.

[0028] Step (2): Regulation of active site density

[0029] After deposition in step (1) is completed, the flow of reactive gas and precursor is stopped and the plasma power supply is turned off. The substrate is kept in a vacuum environment for 1 min to 3 min, preferably 2 min. This interval process reduces the number and density of active groups on the surface of the deposited layer, which is a key step in inducing local selective nucleation of subsequent TMCTS fragments.

[0030] During the PECVD deposition process, the surface of the initial deposited layer generated in step (1) contains a large number of high-energy active free radicals (such as Si). SiO (etc.). By allowing these active free radicals to remain in a vacuum for 1-3 minutes, partial relaxation and self-quenching occur, enabling controllable adjustment of the active site density. If the resting time is too short (<1min), the density of active sites is too high and the distribution is uniform, which leads to the TMCTS fragments in step (3) undergoing full nucleation on the surface, forming a disordered continuous film instead of an ordered microstructure; If the standing time is too long (>3 min), the active sites will disappear excessively and the density of residual active sites will be too low, making it difficult to induce the nucleation and growth of cellular or island-like structures, and the surface will remain relatively smooth. Within the 1-3 min time range defined by this invention, local selective distribution of active sites can be achieved—some active sites are quenched to form inert regions, while some active sites are retained to form active regions. This non-uniform distribution lays the foundation for the subsequent directional anchoring of TMCTS fragments and the construction of ordered microstructures.

[0031] Step (3): Construction of ordered microstructures

[0032] On the surface treated in step (2), PECVD deposition is performed using TMCTS (tetramethylcyclotetrasiloxane) and O2 as the reaction gases. The preferred flow ratio of TMCTS to O2 is 1:1, the deposition pressure is controlled within the range of 40-80 Pa, and the deposition time is 5-15 min. Similar to step (1), the plasma power supply is controlled within the range of 100-200 W, preferably 120-150 W.

[0033] Under plasma irradiation, TMCTS molecules are activated and generate free radicals and ionic fragments. These active fragments preferentially undergo reaction anchoring and nucleation growth at the active sites formed in step (2), while deposition in inert regions is relatively inhibited. By synergistically regulating the precursor chemical properties (the cyclic siloxane structure of TMCTS), the local distribution of active sites, and deposition kinetics, TMCTS fragments preferentially nucleate and gradually grow at the active sites, eventually forming ordered cellular or island-like microstructures.

[0034] Deposition time has a significant impact on microstructure morphology: when the deposition time is 5 min, the microstructure is in the early stage of nucleation, with small cell units (about 0.3-0.5 μm) and low height; when the deposition time is 10 min, the microstructure is mature, with moderately sized cell units (about 0.5-0.8 μm), arranged in an orderly manner and with uniform height; when the deposition time is extended to 15 min, the microstructure continues to grow, and the unit size increases (about 0.8-1.2 μm), but excessively long deposition time may cause adjacent microstructure units to merge, and the orderliness decreases slightly.

[0035] Plasma power also plays a crucial role in microstructure formation: when the power is 100W, the activation level of TMCTS is insufficient, the number of active fragments is limited, and the formed microstructures are uneven in size and irregularly distributed; when the power is increased to 200W, the excessively high plasma energy leads to intensified competition between the deposition and etching processes, and the microstructures are bombarded and etched by high-energy particles while growing, resulting in irregular morphology; within the preferred range of 120-150W, the precursor is fully activated and the deposition process is controllable, which can form uniformly sized and orderly arranged cellular or island-like microstructures.

[0036] Step (4): Construction of the superhydrophilic functional layer

[0037] The microstructured surface obtained in step (3) is subjected to oxygen plasma modification treatment, and a hydrophilic polymer monomer is introduced for plasma graft polymerization to construct a superhydrophilic functional layer. The preferred hydrophilic polymer monomer of this invention is acrylic acid.

[0038] Specifically, the construction process of the superhydrophilic functional layer includes: first, introducing O2 into the cavity for plasma modification treatment, introducing active groups such as hydroxyl and carboxyl groups onto the surface of the microstructure, while removing residual organic debris to provide active sites for subsequent grafting; then, introducing a mixed gas of acrylic acid and O2, with the preferred flow ratio of acrylic acid to O2 being 2:1, and carrying out graft polymerization under discharge conditions, where acrylic acid monomers undergo free radical polymerization at the active sites and anchor to the microstructure surface through chemical bonds; finally, turning off O2 and continuously introducing acrylic acid gas for subsequent reactions, allowing the acrylic acid polymer molecular chains to further extend and crosslink. The graft polymerization temperature is preferably 50-80℃, and the time is 10-20 min.

[0039] Through the above graft polymerization process, an acrylic polymer hydrophilic layer was constructed on the surface of the ordered microstructure. The thickness of this hydrophilic layer can be controlled within the range of 5-50 nm by adjusting the graft polymerization time and acrylic acid flow rate: when the graft polymerization time is short (about 2 min) and the acrylic acid flow rate is low (about 20 sccm), the thickness of the hydrophilic layer is about 5-8 nm; when the graft polymerization time is extended and the acrylic acid flow rate is increased, the thickness of the hydrophilic layer increases accordingly, reaching a maximum of 45-50 nm. After PECVD treatment, the hydrophilic layer forms a stable network with a cross-linked structure, and the abundant carboxyl groups (-COOH) in the acrylic acid molecular chain endow the surface with excellent hydrophilicity.

[0040] The ordered microstructured superhydrophilic coating prepared by this invention comprises the following three layers from the substrate outwards: The first layer—the initial silicone smoothing layer: This layer is deposited on the surface of the glass substrate by PECVD with HMDSO and O2 as reactive gases. It is about 20-30 nm thick and contains a Si-O-Si framework structure and Si-OH active groups. The surface is smooth and dense, forming a strong chemical bond with the glass substrate.

[0041] The second layer—an ordered cellular microstructure layer: This layer is formed by PECVD deposition of TMCTS and O2 as reactant gases on the initial smooth silicone layer. Due to the 2-minute vacuum settling in step (2), the active groups on the surface of the initial layer partially relax, resulting in a non-uniform distribution of active and inert regions. TMCTS fragments preferentially nucleate and gradually grow at the active sites, ultimately forming an ordered cellular microstructure. Characterization by AFM and SEM revealed that the microstructure units are approximately 0.5-0.8 μm in size, arranged in an orderly and highly uniform manner.

[0042] The third layer—the acrylic polymer hydrophilic layer—is formed by plasma grafting polymerization of acrylic acid after oxygen plasma activation treatment. The acrylic polymer molecular chains are anchored to the microstructure surface via chemical bonds (covalent bonds), forming a stable network with a cross-linked structure. The abundant carboxyl groups (-COOH) in the hydrophilic layer bind to water molecules through hydrogen bonds, endowing the coating with superhydrophilic properties.

[0043] The static water contact angle of the above coating surface is 4.8°, which is much less than 5°, reaching a superhydrophilic state; the visible light transmittance is 98%, meeting the requirements for optical transparency; the anti-fog effectiveness in an 80℃ water vapor environment is greater than 70 days, demonstrating excellent long-term stability.

[0044] The coating's superhydrophilicity and long-lasting anti-fogging properties stem from the synergistic effect of its microstructure and surface chemistry: (1) Capillary action of ordered microstructures: Cellular or island-like microstructures form regularly arranged capillary channels on the surface. When a water droplet comes into contact with the surface, capillary force drives the water droplet to spread rapidly along the channel, accelerating the transformation of the water droplet into a continuous water film. At the same time, the microstructure has a pinning effect on the liquid interface, making the formed water film less likely to break or shrink when subjected to external disturbances. (2) Chemical affinity of acrylic hydrophilic layer: The carboxyl groups in the acrylic polymer molecular chain form hydrogen bonds with water molecules, which reduces the interfacial energy between the surface and water and promotes the uniform spread of water film on the surface; the cross-linked network structure gives the hydrophilic layer good chemical stability and makes it less susceptible to oxidation, contamination or degradation. (3) Guarantee of optical performance by ordered structure: Compared with disordered microstructure, ordered microstructure has regular arrangement and specific spatial frequency distribution, which effectively avoids multi-angle scattering and haze increase caused by random height fluctuations and scale distribution, and maintains the high transparency of the material while providing capillary channels; In addition, ordered microstructure can form a refractive index gradient layer between air and substrate, reducing light reflection loss at the interface.

[0045] The specific implementation steps and effects of this application will be described in detail below through examples and comparative examples.

[0046] Example 1

[0047] A method for preparing a superhydrophilic surface constructed with ordered microstructures includes the following steps: (1) After wiping the glass substrate with anhydrous ethanol and drying it, the substrate was placed in the PECVD chamber and the vacuum was reduced to 3Pa. First, 20sccm HMDSO and 12sccm O2 were introduced. The plasma power was set to 130W and the reaction was controlled within 1min-3min. If the interval time was too short (<1min), the active sites would not be fully relaxed. If it was too long (>3min), the active sites would be over-quenched, affecting the microstructure growth density. In this embodiment, the reaction time was 2min, and an initial organosilicon deposition layer containing Si–O–Si / Si–OH was formed on the substrate surface. (2) After deposition in step (1), the plasma power supply is turned off and the introduction of HMDSO and O2 is stopped, with an interval of 2 min, thereby regulating the density of surface active groups; (3) Based on step (2), continue deposition by introducing 10 sccm of TMCTS and 12 sccm of O2. Set the plasma power supply to 130W and react for 10 min. Then turn off the plasma power supply and stop introducing TMCTS and O2. After the pressure in the chamber drops to 10 Pa, remove the sample. A substrate with an ordered microstructure is obtained; the schematic diagram of the substrate surface morphology is shown below. Figure 1 The morphology of the base section is as follows Figure 2 As shown; (4) Leave the activated substrate with ordered microstructure obtained in step (3) in the plasma chamber, evacuate to a pressure of 3 Pa, introduce 12 sccm of O2, set the plasma power supply voltage to 700 V, react for 10 min, then introduce 20 sccm of O2 and 40 sccm of acrylic acid (i.e., the flow ratio of acrylic acid to O2 is 2:1), set the plasma power supply voltage to 700 V, react for 2 min, then turn off the plasma power supply, turn off the oxygen and angle valve, and introduce acrylic acid for 10 min.

[0048] Example 2

[0049] The difference between this embodiment and Embodiment 1 is that a silicon wafer is used as the substrate. All other aspects are the same as in Embodiment 1. That is, in this embodiment, an ordered microstructure is prepared on the surface of the silicon wafer and a superhydrophilic coating is constructed.

[0050] Example 3

[0051] A method for preparing a superhydrophilic surface constructed with ordered microstructures includes the following steps: (1) After wiping the glass substrate with anhydrous ethanol and drying it, the substrate was placed in the PECVD chamber and the vacuum was drawn to reduce the pressure to 3Pa. First, 20sccm HMDSO and 12sccm O2 were introduced. The plasma power was set to 130W and the reaction was carried out for 2min to form an initial organosilicon deposition layer containing Si–O–Si / Si–OH on the substrate surface. (2) After deposition in step (1), the plasma power supply is turned off and the introduction of HMDSO and O2 is stopped, with an interval of 1 min, thereby regulating the density of surface active groups; (3) Based on step (2), continue deposition by introducing 10 sccm of TMCTS and 12 sccm of O2. Set the plasma power supply to 130W and react for 5 minutes. Then, turn off the plasma power supply and stop introducing TMCTS and O2. Wait for the pressure inside the chamber to drop to 10 Pa before removing the sample. A substrate with an ordered microstructure is obtained; a schematic diagram of the substrate surface morphology is shown below. Figure 4 As shown; (4) Leave the activated substrate with ordered microstructure obtained in step (3) in the plasma chamber, evacuate to a pressure of 3 Pa, introduce 12 sccm O2, set the plasma power supply voltage to 700 V, react for 10 min, then introduce 20 sccm O2 and 40 sccm acrylic acid, set the plasma power supply voltage to 700 V, react for 2 min, then turn off the plasma power supply, turn off the oxygen and angle valve, and introduce acrylic acid for 10 min.

[0052] Example 4

[0053] A method for preparing a superhydrophilic surface constructed with ordered microstructures includes the following steps: (1) After wiping the glass substrate with anhydrous ethanol and drying it, the substrate was placed in the PECVD chamber and the vacuum pressure was 3Pa. First, 20sccm HMDSO and 12sccm O2 were introduced. The plasma power was set to 130W and the reaction was carried out for 2min to form an initial organosilicon deposition layer containing Si–O–Si / Si–OH on the substrate surface. (2) After deposition in step (1), the plasma power supply is turned off and the introduction of HMDSO and O2 is stopped, with an interval of 2 min, thereby regulating the density of surface active groups; (3) Based on step (2), continue deposition by introducing 10 sccm of TMCTS and 12 sccm of O2. Set the plasma power supply to 130W and react for 15 minutes. Then, turn off the plasma power supply and stop introducing TMCTS and O2. Wait for the pressure inside the chamber to drop to 10 Pa before removing the sample. A substrate with an ordered microstructure is obtained; the schematic diagram of the substrate surface morphology is shown below. Figure 1 The morphology of the base section is as follows Figure 5 As shown; (4) Leave the activated substrate with ordered microstructure obtained in step (3) in the plasma chamber, evacuate to a pressure of 3 Pa, introduce 12 sccm O2, set the plasma power supply voltage to 700 V, react for 10 min, then introduce 20 sccm O2 and 40 sccm acrylic acid, set the plasma power supply voltage to 700 V, react for 2 min, then turn off the plasma power supply, turn off the oxygen and angle valve, and introduce acrylic acid for 10 min.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that steps (1) to (3) are omitted, and step (4) is performed directly on the substrate. All other steps are the same as in Example 1. That is, this comparative example grafts a superhydrophilic coating onto a blank substrate.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that the monomers in step (1) and step (3) are interchanged, while the rest are the same as in Example 1. That is, this comparative example first performs the deposition of TMCTS+O2, and then performs the deposition of HMDSO+O2.

[0058] Comparative Example 3

[0059] The difference between this comparative example and Example 1 is that step (1) is omitted, while the rest is the same as in Example 1. That is, HMDSO+O2 layer deposition is not performed in this comparative example.

[0060] Comparative Example 4

[0061] The difference between this comparative example and Example 1 is that the 2-minute interval in step (1) is omitted; otherwise, it is the same as Example 1. That is, in this comparative example, TMCTS+O2 deposition is performed directly after HMDSO+O2 deposition.

[0062] Comparative Example 5

[0063] The difference between this comparative example and Example 1 is that the interval of 2 min in step (1) is changed to an interval of 5 min, while the rest is the same as in Example 1. That is, in this comparative example, TMCTS+O2 deposition is performed after a 5 min interval following the deposition of HMDSO+O2.

[0064] Comparative Example 6

[0065] The difference between this comparative example and Example 1 is that step (3) is omitted, while the rest is the same as in Example 1. That is, this comparative example does not perform TMCTS+O2 layer deposition.

[0066] Comparative Example 7

[0067] The difference between this comparative example and Example 1 is that the deposition power in step (3) is changed and the plasma power supply power is set to 100W. All other aspects are the same as in Example 1.

[0068] Comparative Example 8

[0069] The difference between this comparative example and Example 1 is that the deposition power in step (3) is changed and the plasma power supply power is set to 200W. All other aspects are the same as in Example 1.

[0070] Comparative Example 9

[0071] The difference between this comparative example and Example 1 is that the gas ratio in step (3) is changed, and the ratio of TMCTS to O2 is set to 7:3. All other aspects are the same as in Example 1.

[0072] Comparative Example 10

[0073] The difference between this comparative example and Example 1 is that the gas ratio in step (3) is changed, and the ratio of TMCTS to O2 is set to 3:7. All other aspects are the same as in Example 1.

[0074] Comparative Example 11

[0075] The difference between this comparative example and Example 1 is that the oxygen plasma pretreatment in step (4) is replaced with argon plasma pretreatment, while the rest are the same as in Example 1.

[0076] Comparative Example 12

[0077] The difference between this comparative example and Example 1 is that the acrylic acid gas grafting in step (4) is not performed, that is, only oxygen plasma modification treatment is performed without introducing acrylic acid monomers, and the rest is the same as Example 1.

[0078] The static water contact angle and visible light transmittance of the surfaces obtained in the examples and comparative examples, as well as the untreated glass substrates and silicon wafer substrates, were tested using the following methods: The static contact angle and dynamic sliding angle of the prepared coatings were tested using a Kruss DSA 100 contact angle meter. All static contact angles were measured using 5 μL water droplets. At least five different areas of each coating were measured, and the average value was taken as the final value. The visible light transmittance of the prepared coatings was tested using a TU-1950 UV-Vis spectrophotometer. A blank glass slide was used as the background, and the scanning wavelength was 350-780 nm. The test results are shown in Table 1. Since the silicon substrate is opaque, the coating transmittance and anti-fogging tests could not be performed; therefore, they are indicated by " / ".

[0079] Table 1 Surface test results of the examples and comparative examples

[0080] Surface water contact angle of Example 1 is as follows Figure 3 As shown, Figure 13 - Figure 1 Figure 5 shows a comparison of the anti-fogging effects of Example 1, Comparative Example 1, and an untreated glass sheet under water vapor at 80°C, where c is the untreated glass sheet, b is Comparative Example 1, and a is Example 1. Figure 13 This is a comparison of the anti-fog effect on the first day. Figure 14 This is a comparison image showing the anti-fog effect on the fourth day. Figure 15 This is a comparison image showing the anti-fog effect on the seventh day. Figure 13 - Figure 1 The English background in Figure 5 primarily compares the anti-fog effect by the clarity of the English letters.

[0081] Based on the data in Table 1 and Figures 13-15 It can be seen that the surface prepared by the method of the present invention has excellent transparency and anti-fogging durability. The untreated glass slide has a water contact angle of 45° and poor hydrophilicity. It fogs up quickly when placed on 80°C water vapor. In Comparative Example 1, no microstructure film was constructed on the substrate, the surface is smooth, and there is no microstructure and graft coating to work together to prevent fogging, resulting in poor anti-fogging durability. In Comparative Example 2, the monomers in steps (1) and (2) were interchanged, and the light transmittance and hydrophilicity were significantly reduced. In Comparative Example 3, step (1) was not performed, and TMCTS+O2 deposition was performed directly. The results showed that the surface roughness was large and the light transmittance was poor.

[0082] In Comparative Example 4, the interval between steps (1) and (2) was not 2 minutes, resulting in higher light transmittance and lower roughness. However, due to the lack of surface structure, the anti-fog durability was significantly reduced. In Comparative Example 5, the interval in step (1) was changed to 5 minutes, resulting in lower light transmittance, higher roughness, and an irregular surface structure, which also significantly reduced the anti-fog durability.

[0083] In Comparative Example 6, step (2) was omitted, i.e., HMDSO + O2 was directly deposited. The surface roughness was low, and the light transmittance was good, but there was no microstructure synergistic optimization of anti-fogging performance, resulting in poor anti-fogging durability. In Comparative Example 7, the deposition power in step (2) was changed, and the plasma deposition power was set to 100W. Irregular microstructures were generated on the surface, resulting in poor light transmittance and poor anti-fogging durability after grafting. In Comparative Example 8, the plasma power was set to 200W. Microstructures were generated on the resulting surface, but the surface microstructures were irregular, and the transmittance was not affected. The anti-fogging durability was also poor. In Comparative Example 9, the gas ratio in step (2) was changed, and the ratio of TMCTS to O2 was set to 7:3. Microstructures were generated after deposition, but the density of the generated microstructures was low and not obvious. The anti-fogging durability after grafting was poor. Comparative Example 10 changed the gas ratio in step (2), setting the ratio of TMCTS to O2 to 3:7. The deposited surface was smooth and had no microstructure, with good light transmittance. In Comparative Example 11, the oxygen plasma pretreatment in step (3) was changed to argon plasma pretreatment. It was found that the surface pretreated with argon plasma had poor hydrophilicity and did not play an anti-fogging role. In Comparative Example 12, the surface was not modified with oxygen plasma and hydrophilic molecular linkages were not applied. The surface water contact angle was too large, and it was in a hydrophobic state, with no anti-fogging performance.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A superhydrophilic surface coating constructed with an ordered microstructure, characterized in that, The coating comprises, from the substrate outwards, the following: An initial organosilicon smoothing layer containing Si-O-Si / Si-OH bonds was deposited on the substrate surface using PECVD with HMDSO and O2 as reactant gases. An ordered cellular or island-like microstructure layer is formed on the initial smooth silicone layer. This microstructure layer is composed of a silicone polymer containing Si-O-Si bonds, and the microstructure unit size is 0.3-1.2 μm. These microstructure units are orderly arranged and distributed on the initial smooth silicone layer. A hydrophilic polymer layer is chemically bonded to the surface of the microstructure layer.

2. The superhydrophilic surface coating constructed with ordered microstructures according to claim 1, characterized in that, The hydrophilic polymer layer is an acrylic polymer hydrophilic layer, in which the carboxyl groups are bonded to water molecules through hydrogen bonds, giving the coating superhydrophilic properties.

3. The superhydrophilic surface coating constructed with ordered microstructures according to claim 2, characterized in that, The thickness of the acrylic polymer hydrophilic layer is 5-50 nm, and the hydrophilic layer is treated with PECVD to form a stable network with a cross-linked structure.

4. A method for preparing a superhydrophilic surface coating constructed with an ordered microstructure as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Using PECVD, HMDSO and O2 are used as reaction gases to form an initial organosilicon deposition layer containing Si–O–Si / Si–OH on the substrate surface; (2) After deposition in step (1), stop the introduction of reactive gas and precursor and turn off the plasma power supply. Keep the substrate in a vacuum environment for 1 min to 3 min to reduce the number and density of active groups on the surface of the deposited layer. (3) The surface treated in step (2) is subjected to PECVD deposition with TMCTS and O2 as reaction gases under the condition of plasma power of 120-150W. The flow ratio of TMCTS to O2 is 1:

1. The free radicals and ion fragments generated after plasma activation of TMCTS are anchored to the active sites by the reaction, so that they preferentially nucleate and grow at the active sites to form ordered cellular or island microstructures. (4) The surface with microstructure obtained in step (3) is activated by oxygen plasma and hydrophilic polymer monomers are introduced for plasma grafting polymerization to construct a superhydrophilic functional layer.

5. The method for preparing a superhydrophilic surface coating constructed with an ordered microstructure according to claim 4, characterized in that, In step (2), the substrate is kept in a vacuum environment for 2 minutes.

6. The method for preparing a superhydrophilic surface coating constructed with an ordered microstructure according to claim 4, characterized in that, In step (1), the HMDSO to O2 flow rate ratio is 2:1, the deposition pressure is 40-70 Pa, and the deposition time is controlled at 2-5 min.

7. The method for preparing a superhydrophilic surface coating constructed with an ordered microstructure according to claim 4, characterized in that, In step (3), the deposition pressure is 40-80 Pa and the deposition time is 5-15 min.

8. The method for preparing a superhydrophilic surface coating constructed with an ordered microstructure according to claim 4, characterized in that, The hydrophilic polymer monomer in step (4) is acrylic acid.

9. The method for preparing a superhydrophilic surface coating constructed with an ordered microstructure according to claim 8, characterized in that, The construction of the superhydrophilic functional layer in step (4) specifically includes: first, introducing O2 into the cavity for plasma activation treatment; then introducing a mixed gas of acrylic acid and O2, and performing graft polymerization under discharge conditions; finally, turning off O2 and continuously introducing acrylic acid gas for subsequent reactions; the ratio of the mixed gas of acrylic acid and O2 is 2:1, and the graft polymerization temperature is 50-80℃, and the time is 10-20min.

10. The method for preparing a superhydrophilic surface coating constructed with an ordered microstructure according to claim 4, characterized in that, In step (1), the substrate includes any one of silicon wafer, glass, ceramic, metal, and plastic.

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