Liquid-like polymer brush anti-icing coating as well as preparation method and application thereof

Abstract

The invention discloses a liquid-like polymer brush anti-icing coating as well as a preparation method and application thereof, a liquid-like coating is constructed through a single-end free macromolecular chain, the adhesion strength of ice and a solid surface is effectively reduced, and a polymer brush is rapidly formed on various substrates (including glass, metal, ceramic and the like). According to the invention, liquid-like properties are provided for the coating by utilizing the unique flexibility of siloxane with terminal reactive groups, and the coating shows low contact angle hysteresis and low ice adhesion strength. And meanwhile, perfect acid and alkali corrosion resistance, ultraviolet (UV) degradation and even dozens of ice / deicing cycles are shown. The glass has wide application in the outdoor engineering fields of automobile glass, electric power communication, fan blades, aviation and the like.

Description

Technical Field

[0001] The present invention belongs to the field of engineering technology (materials), and particularly relates to a liquid-like polymer brush anti-icing coating, a preparation method thereof, and an application thereof. Background Art

[0002] The icing phenomenon is widespread in nature and is of extremely important significance for maintaining the ecological balance of the earth. In human production and life, ice has very crucial application values in fields such as food preservation, biomedicine, and tissue engineering. However, the existence of the ice covering phenomenon will also bring many potential hazards to fields such as transportation, communication, electric power, aviation, and military. In severe cases, it will even cause major disasters and accidents, and even result in huge economic losses and endanger lives.

[0003] Currently, the de-icing methods commonly used at home and abroad are divided into three categories, including physical methods (such as mechanical de-icing, heating de-icing), chemical methods (such as spraying brine, anti-icing agents), and passive anti-icing (such as coating technology). The first two methods have many problems such as high working intensity, low efficiency, environmental pollution, and being restricted by time and space. Passive anti-icing is mainly to construct an anti-icing functional coating on the surface of the substrate to reduce the adhesion force of ice to the substrate surface and the amount of ice covering. Compared with physical methods and chemical methods, this method of coating a functional coating has many advantages such as low cost, low energy consumption, and easy implementation, and is an ideal anti-icing technology, thus having great application value. However, there are still many problems in the existing anti-icing coating technology in actual application scenarios (such as poor mechanical properties, poor chemical stability, etc.), making it unable to meet the actual application needs of society. Therefore, the research on long-term stable anti-icing coating technology is a major and urgently needed technical problem to be solved at home and abroad.

[0004] In recent years, biomimetic materials have been extensively studied in both basic science and practical applications, with a series of anti-icing coating technologies proposed, including superhydrophobic anti-icing coatings, oil-lubricated anti-icing coatings, water-lubricated anti-icing coatings, and liquid-like polymer brush anti-icing coatings. Among these, the superhydrophobic surface technology, which mimics the lotus leaf structure, effectively reduces the contact area between ice and the surface by trapping a certain thickness of air layer within a micro-nano composite structure modified with a low surface energy coating, thereby delaying the freezing of water droplets. Simultaneously, the superhydrophobic surface can also rapidly remove water droplets, thereby reducing the amount of water accumulated on the surface and effectively inhibiting the formation and transfer of ice. However, the metastable air layer on the superhydrophobic surface is unstable under low temperature, high humidity, and / or high pressure. Condensation within the water droplet structure causes the surface droplets to undergo a Cassie-Wenzel transition, ultimately causing the surface to lose its superhydrophobicity. Furthermore, inspired by the Nepenthes pitcher plant, Aizenberg of Harvard University infused an inert liquid onto a substrate with a micro-nano composite porous structure to create a continuous lubricant liquid layer. Due to the laminar sliding properties of the surface oil phase and the presence of a molecularly smooth liquid layer, the ice adhesion strength on the surface of oil-lubricated materials can be reduced to less than 10 kPa, thus achieving an anti-icing effect. However, low-surface-energy lubricating liquids often suffer from drawbacks such as evaporation, migration, and loss, which shorten the service life of oil-lubricated materials. Furthermore, the loss of lubricating liquid can cause certain environmental pollution.

[0005] Liquid-like polymer brush coatings, prepared by grafting hydrophobic, flexible polymer chains onto solid surfaces in the form of polymer brushes, exhibit hydrophobic and ice-repellent properties very similar to those of oil-lubricated anti-icing materials. The high mobility of the molecular chains in liquid-like polymer brushes enables self-lubrication without the need for a liquid lubricant. With their excellent anti-icing properties and good chemical and mechanical stability, these materials are becoming a new strategy for developing anti-icing coatings. However, the preparation methods for these surfaces remain relatively complex, making the rapid preparation of low-adhesion anti-icing surfaces within a short timeframe crucial for practical applications. Summary of the Invention

[0006] In order to improve the above technical problems, the present invention provides a simple method for quickly forming a polydimethylsiloxane (PDMS) brush anti-icing coating on a substrate within a wide temperature range.

[0007] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0008] A coating comprises polysiloxane, which is a polymer brush formed by grafting siloxane with terminal reactive groups onto a substrate.

[0009] Preferably, the end - group reactive groups of the polysiloxane are grafted onto the substrate by covalent bonds.

[0010] According to an embodiment of the present invention, the siloxane having end - group reactive groups is selected from low - molecular - weight chlorosilane bis - end - group silane monomers (such as at least one of dichlorodimethylsilane, 1,3 - dichlorotetramethyldisiloxane, and dimethoxydimethylsilane, etc.) or high - molecular - weight mono - end - group siloxanes (such as trimethoxy - terminated polysiloxane or vinyl - end - group polysiloxane, etc.).

[0011] According to an embodiment of the present invention, the weight - average molecular weight of the high - molecular - weight mono - end - group siloxane is 1000 - 100000, and examples are 1000, 3000, 5000, 8000, 10000, 20000, 50000, 100000.

[0012] According to an embodiment of the present invention, the thickness of the coating is 1 - 10 nm, preferably 3 - 10 nm, and an example is 7 nm.

[0013] According to an embodiment of the present invention, the ice adhesion strength on the surface of the coating is less than 30 kPa, such as 25 kPa, 20 kPa.

[0014] According to an embodiment of the present invention, the coating is a liquid - like polymer brush anti - ice coating.

[0015] According to an embodiment of the present invention, the coating is a polymer brush formed by grafting a siloxane having end - group reactive groups onto a substrate.

[0016] According to an embodiment of the present invention, the grafting method is: coating a solution of a siloxane having end - group reactive groups on the substrate and / or immersing the substrate in a solution of a siloxane having end - group reactive groups. For example, the solvent used in the solution is a good solvent for the siloxane. Preferably, the solvent is at least one of isopropyl alcohol, ethanol, n - hexane, acetone, toluene (preferably water - saturated toluene), and ethylene glycol, etc.

[0017] According to an embodiment of the present invention, the concentration of the siloxane having end - group reactive groups in the solution is 1 - 10%, and examples are 1%, 2%, 5%, 8%, 10%.

[0018] According to an embodiment of the present invention, the solution may further contain an acid catalyst. For example, the acid catalyst includes molecules that can generate hydrogen ions, such as at least one of hydrochloric acid, Lewis acid, and chlorosilane.

[0019] In one embodiment of the present invention, the acid catalyst can be the same as the siloxane having end - group reactive groups. For example, the acid catalyst can be dichlorodimethylsilane, 1,3 - dichlorotetramethyldisiloxane.

[0020] According to an embodiment of the present invention, the concentration of the acid catalyst in the solution is 0.1-1%, and examples are 0.1%, 0.2%, 0.5%, 0.8%, 1%.

[0021] In the present invention, the mechanism of hydrogen ion generation by the hydrolysis of chlorosilane is as follows:

[0022] R3SiCl + H2O → R3SiOH + HCl

[0023] R2SiCl2 + H2O → R2Si(OH)2 + 2HCl

[0024] RSiCl3 + H2O → RSi(OH)3 + 3HCl

[0025] According to an embodiment of the present invention, the soaking time can be, for example, 10 s to 2 h.

[0026] According to an embodiment of the present invention, the substrate is at least one of metal, silicon wafer, plastic, glass, ceramic, wood, and polymer, etc.

[0027] The present invention also provides a method for preparing the above coating, including forming a chain structure on the substrate spontaneously in a solution with a siloxane having a terminal reactive group.

[0028] According to an embodiment of the present invention, the method for preparing the coating includes the following steps:

[0029] 1) Coating a solution of a siloxane having a terminal reactive group on the substrate and / or soaking the substrate in a solution of a siloxane having a terminal reactive group to prepare the coating.

[0030] According to an embodiment of the present invention, the method for preparing the coating further includes step 2): washing the residual solution on the surface of the coating and drying to form the coating. For example, the solvent for washing can be toluene or isopropanol.

[0031] The present invention also provides applications of the above coating in the fields of food preservation, biomedicine, tissue engineering, transportation, communication, electric power, wind turbine blades, aviation, military, etc. For example, it is applied to surface anti-icing and / or de-icing in the fields of automobiles, ships, aviation, etc.

[0032] The present invention also provides a method for anti-icing and / or de-icing, including applying the above siloxane having a terminal reactive group to the surface of the substrate body.

[0033] According to an embodiment of the present invention, the substrate body is at least one of metal, silicon wafer, plastic, glass, ceramic, wood, and polymer, etc.

[0034] According to an embodiment of the present invention, the application can be selected from means known in the art, such as spraying, roller coating, brushing, coating, dipping, etc., for applying the siloxane having terminal reactive groups on the surface of the substrate body.

[0035] The present invention also provides the application of the above anti-icing and / or de-icing method in the fields of food preservation, biomedicine, tissue engineering, transportation, communication, electric power, fan blades, aviation, military, etc. For example, it is applied to surface anti-icing and / or de-icing in the fields of automobiles, ships, aviation, etc.

[0036] Advantages of the present invention:

[0037] (1) Due to the lubricating effect of the liquid-like substance, the PDMS brush of the present invention shows dynamic repellency to liquids with different surface tensions. Droplets of water, dimethyl sulfoxide, propylene glycol, etc. can easily slide on the surface of the PDMS polymer brush with an inclined angle of the present invention without any adhesion phenomenon.

[0038] (2) The present invention further studied the performance of the liquid-like PDMS brush in anti-solid adhesion. Taking the lateral adhesion strength τ = F / A of the solid contaminant on the surface as the standard for determining the surface's ability to resist solid adhesion. By studying the adhesion of paint on silicon wafers, it was found that the PDMS brush has significant advantages in reducing solid adhesion. On the PDMS polymer brush of the present invention, the paint can be completely torn off.

[0039] (3) The ice adhesion strength on the surface of the PDMS polymer brush of the present invention decreased by 10 times from 200 kPa to 20 kPa, showing good anti-ice adhesion ability. And after multiple breakages and re-coatings, the coating can still continue to play its role.

[0040] (4) The PDMS polymer brush of the present invention can be applied to different substrate surfaces, and can reduce the ice adhesion strength on the surfaces of metals, plastics, glass, silicon wafers, etc.

[0041] (5) The present invention constructs a liquid-like coating through a single-ended free polymer chain, effectively reducing the ice adhesion strength between ice and the solid surface, and realizing the rapid formation of polymer brushes on various substrates, including glass, metal, ceramics, etc. The present invention utilizes the unique flexibility of the siloxane having terminal reactive groups to endow the coating with liquid-like properties, showing low contact angle hysteresis and low ice adhesion strength. At the same time, it shows perfect resistance to acid-base corrosion, ultraviolet (UV) degradation, and even dozens of ice / de-icing cycles. It has wide applications in outdoor engineering fields such as automotive glass, electric power communication, fan blades, and aviation. Description of the Drawings

[0042] Figure 1Sliding pictures of 20 μL water droplets, dimethyl sulfoxide, and propylene glycol droplets on the PDMS brush coating surface prepared in Example 1.

[0043] Figure 2 Ice adhesion strength result graph of the PDMS brush coating prepared in Example 1 after multiple etching-grafting processes.

[0044] Figure 3 Adhesion performance result graph of paint on the glass and the PDMS brush coating surface prepared in Example 2.

[0045] Figure 4 Adhesion schematic diagram of paint on the PDMS brush coating surface prepared in Example 2.

[0046] Figure 5 Universal experiment result graph of the PDMS brush coating of Example 3 on different substrates. Detailed implementation mode

[0047] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only for illustrative and explanatory purposes of the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0048] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

[0049] Example 1

[0050] A preparation method of a liquid-like polymer brush coating includes the following steps:

[0051] Using trimethoxy-terminated polydimethylsiloxane with a weight average molecular weight of 3000 as the main component, with a weight fraction of 5 parts, dichlorodimethylsilane as an acid catalyst, with a weight fraction of 0.5 parts, 100 parts of isopropanol, and ultrasonically mixing for 10 min to obtain a reaction solution. Immerse the oxygen plasma-etched silicon wafer in the reaction solution for a certain time (from 1 min to 120 min), then take out the silicon wafer, wash it successively with toluene and isopropanol after the solvent volatilizes, and dry it with compressed air to obtain the PDMS brush coating surface.

[0052] This process has a rapid reaction. Within 1 min of the reaction time, the contact angle of the silicon wafer rapidly increases to about 100°, already having a hydrophobic effect; when the soaking time (grafting time) is 30 min, the overall orientation degree of the PDMS brush increases, the thickness increases, and the contact angle hysteresis of water decreases to 5°, having obvious hydrophobic and solid-repellent properties. And the ice adhesion strength on the PDMS brush surface also decreases from 50 kPa at 1 min of soaking reaction to about 20 kPa.

[0053] 20 μL of deionized water, dimethyl sulfoxide, and propylene glycol were respectively drop-coated on the surface of the PDMS brush coating prepared in this example, and the phenomena of water droplets, dimethyl sulfoxide droplets, and propylene glycol droplets sliding on the surface of the PDMS brush coating were observed. The results are as Figure 1 shown. It can be seen from the figure that: using the PDMS brush coating material prepared in Example 1, it has excellent dynamic low adhesion performance for water, dimethyl sulfoxide, and propylene glycol. Through surface tilting, water droplets, dimethyl sulfoxide droplets, and propylene glycol droplets can all achieve residue-free and pinning-free sliding.

[0054] Taking trimethoxy-terminated polydimethylsiloxane with a weight-average molecular weight of 3000 as the main component, with a weight fraction of 5 parts, dichlorodimethylsilane as an acid catalyst, with a weight fraction of 0.5 parts, 100 parts of isopropanol, and ultrasonic mixing for 10 min to obtain a reaction solution. The surface of the PDMS brush coating prepared by immersing in the above reaction solution for 1 min was subjected to oxygen plasma etching treatment. After it became hydrophilic, it was immersed in the reaction solution again for 30 min, then taken out, washed successively with toluene and isopropanol after the solvent evaporated, and dried with compressed air to obtain the surface of the PDMS brush coating. This process was repeated 4 times. The ice adhesion performance of the prepared PDMS brush coating surface was measured respectively. The results are as Figure 2 shown. The results in the figure show that: the PDMS brush coating of the present invention can achieve re-grafting after wear to achieve a long-term anti-icing effect, and after multiple grafting-wear-re-grafting, the surface of the PDMS brush coating of the present invention still exhibits low ice adhesion performance.

[0055] Example 2

[0056] A preparation method of a liquid-like polymer brush coating includes the following steps:

[0057] Taking dichlorodimethylsilane (DCDMS) as the main component, through the self-catalytic polycondensation reaction of hydrochloric acid generated by hydrolysis, linear polydimethylsiloxane is formed on the solid surface. Its weight fraction is 10 parts, and toluene saturated with water is 1000 parts. The solution was rotated and mixed at 3000 rpm for about 30 seconds and left to stand for 5 min at room temperature before use. The oxygen plasma-treated glass slide was immersed in the reaction solution for a certain time (from 30 s to 1 h) to obtain the surface of the PDMS brush coating.

[0058] The surface of the PDMS brush coating obtained by taking out the oxygen plasma-treated glass slide after immersing it in the DCDMS reaction solution for 30 s can remove the residual DCDMS reaction solution on the surface of the PDMS brush coating by simply tilting, without leaving residual stains. When the soaking (grafting) time is 15 min, the molecular weight of the PDMS brush coating increases, the thickness of the PDMS brush coating increases, and the water contact angle hysteresis decreases to less than 5°.

[0059] The PDMS brush coating surface prepared in this example has a lubricating and repulsive effect on common substances in life such as red wine, white wine, seed oil, and castor oil, and can achieve residue-free sliding on the PDMS brush coating surface.

[0060] The paint was respectively scrape-coated onto the oxygen plasma-treated glass (bare substrate surface) and the PDMS brush coating surface (coating surface, the oxygen plasma-treated glass slide was immersed in the DCDMS reaction solution for 15 minutes) of this example, and the adhesion strength of the paint on the oxygen plasma-treated glass and the PDMS brush coating surface was measured. The results are as Figure 3 shown. It can be seen from the figure that for paint stains, the PDMS brush coating surface prepared in this example has significantly reduced adhesion performance, and the adhesion strength of the paint on the PDMS brush coating surface is reduced by one order of magnitude; and on the PDMS brush coating surface prepared in this example, the paint can be completely peeled off as a whole (as Figure 4 ).

[0061] Example 3

[0062] A preparation method of a liquid-like polymer brush coating includes the following steps:

[0063] Dissolve 5 parts of 1,3-dichlorotetramethyldisiloxane in 100 parts of ethanol solution, stir at 60 °C for 2 hours to hydrolyze the 1,3-dichlorotetramethyldisiloxane molecules, release hydrochloric acid, and self-catalyze to form a silicone oxygen long chain with end groups. Immerse the oxygen plasma-treated silicon wafer in the solution for 30 minutes. After the solvent volatilizes, wash the substrate surface with toluene and isopropanol, and dry it with compressed air to obtain the PDMS brush coating surface.

[0064] The PDMS brush coating prepared in this example can reduce the ice adhesion strength to about 20 kPa.

[0065] Example 4

[0066] A preparation method of a liquid-like polymer brush coating, compared with Example 3, the difference is only that: the silicon wafers are sequentially replaced with aluminum sheets, copper sheets, stainless steel, ceramics, glass, and plastics, and PDMS brush coatings are respectively prepared.

[0067] The ice adhesion strengths of the test substrates are respectively silicon wafers, aluminum sheets, copper sheets, stainless steel, ceramics, glass, plastics (bare substrate surfaces) and the corresponding PDMS brush coating surfaces (coating surfaces). The results are as Figure 5As shown. It can be seen from the figure that: in addition to the glass and silicon wafer substrates, the PDMS brush coating prepared from the siloxane with end-group reactive groups in the present invention has a wide range of application scenarios. For substrates such as metals, plastics, and ceramics, the PDMS brush coating of the present invention has the effect of reducing ice adhesion. For the metal surface, the metal surface can be modified into a superhydrophobic surface by grafting a siloxane with end-group reactive groups to form a PDMS brush coating; for a surface with low surface roughness, the ice can be desorbed under gravity or under a small external force by grafting a siloxane with end-group reactive groups to form a PDMS brush coating.

[0068] Above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A coating, characterized in that, The coating includes polysiloxane, and the polysiloxane is a polymer brush formed by grafting siloxane with terminal reactive groups on a substrate. Preferably, the terminal reactive groups of the polysiloxane are grafted on the substrate by covalent bonds.

2. The coating according to claim 1, wherein The siloxane with terminal reactive groups is selected from at least one of low molecular weight chlorosilane bis-terminal silane monomers (such as dichlorodimethylsilane, 1,3-dichlorotetramethyldisiloxane, and dimethoxydimethylsilane, etc.) or high molecular weight mono-terminal siloxanes (such as trimethoxy-terminated polysiloxane or vinyl-terminated polysiloxane, etc.). Preferably, the weight-average molecular weight of the high molecular weight mono-terminal siloxane is 1000 - 100000. Preferably, the thickness of the coating is 3 - 10 nm. Preferably, the ice adhesion strength on the surface of the coating is less than 30 kPa.

3. The coating according to claim 1 or 2, characterized in that, The coating is a polymer brush formed by grafting siloxane with terminal reactive groups on a substrate.

4. The coating according to claim 3, wherein The grafting method is: coating a solution of siloxane with terminal reactive groups on the substrate and / or soaking the substrate in a solution of siloxane with terminal reactive groups. Preferably, the solvent used in the solution is a good solvent for siloxane. Preferably, the solvent is at least one of isopropyl alcohol, ethanol, n-hexane, acetone, toluene (preferably toluene saturated with water), and ethylene glycol, etc. Preferably, the concentration of siloxane with terminal reactive groups in the solution is 1 - 10%.

5. The coating according to claim 4, characterized in that, The solution may also contain an acid catalyst. For example, the acid catalyst includes molecules that can generate hydrogen ions, such as at least one of hydrochloric acid, Lewis acid, and chlorosilane. Preferably, the acid catalyst can be the same as the siloxane with terminal reactive groups. For example, the acid catalyst can be dichlorodimethylsilane, 1,3-dichlorotetramethyldisiloxane. Preferably, the concentration of the acid catalyst in the solution is 0.1 - 1%. Preferably, the soaking time can be, for example, 1 s - 2 h. Preferably, the substrate is at least one of metal, silicon wafer, plastic, glass, ceramic, wood, and polymer, etc.

6. A method for preparing the coating according to any one of claims 1-5, characterized in that, The preparation method includes allowing siloxane with terminal reactive groups to spontaneously form a chain structure on the substrate in a solution.

7. The preparation method according to claim 6, comprising the following steps: 1) Coating a solution of siloxane with terminal reactive groups on the substrate and / or soaking the substrate in a solution of siloxane with terminal reactive groups to prepare the coating. Preferably, the preparation method of the coating further includes step 2): washing the residual solution on the surface of the coating and drying to form the coating. For example, the solvent for washing can be toluene, isopropyl alcohol.

8. Application of the coating according to any one of claims 1 - 5 and / or the coating prepared by the preparation method according to claim 8 in the fields of food preservation, biomedicine, tissue engineering, transportation, communication, electric power, wind turbine blades, aviation, military, etc. For example, it is applied to surface anti-icing and / or de-icing in fields such as automobiles, ships, and aviation.

9. An anti-icing and / or de-icing method, comprising applying the siloxane with terminal reactive groups according to any one of claims 1 - 5 to the surface of the substrate body. Preferably, the substrate body is at least one of metal, silicon wafer, plastic, glass, ceramic, wood, polymer, etc. Preferably, the application is selected from methods such as spraying, roll coating, brushing, coating, dipping, etc. for applying the siloxane having terminal reactive groups on the surface of the substrate body.

10. Application of the anti-icing and / or de-icing method according to claim 9 in the fields of food preservation, biomedicine, tissue engineering, transportation, communication, electric power, wind turbine blades, aviation, military, etc. For example, it is applied to surface anti-icing and / or de-icing in the fields of automobiles, ships, aviation, etc.

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