CN110734700A - super-hydrophobic coating composite material for preventing and removing ice and preparation method thereof - Google Patents

Abstract

The invention discloses super-hydrophobic coating composite materials for preventing and removing ice and a preparation method thereof, wherein the contact angle of the obtained materials is more than 150 degrees, the thickness is 2-5 mu m, the surface of the materials is provided with a rough concave-convex micro-nano structure, Polydimethylsiloxane (PDMS) is used as an adhesive, the materials are obtained by carrying out polymerization reaction with steps and then dip-coating, brushing or spraying the reaction product on the surface of a base material, and the surface of the ring-crosslinked polyphosphazene microsphere is rich in-CF (carbon fluoride)₃The average diameter of the group is 0.5-2 μm, and the mass ratio of the group to PDMS is 1-3: 5. the obtained super-hydrophobic coating composite material has the lotus leaf super-hydrophobic self-cleaning performance, shows good self-cleaning performance and anti-icing performance in a wet and cold environment (15 ℃ below zero and 70% relative humidity), is long in icing delay time, low in adhesion after icing, good in mechanical durability and suitable for being used in the anti-icing and anti-icing field in large-area construction.

Description

super-hydrophobic coating composite material for preventing and removing ice and preparation method thereof

Technical Field

The invention belongs to the technical field of functional composite materials, and particularly relates to super-hydrophobic coating composite materials with efficient durable deicing functions and a preparation method thereof.

Background

According to statistics, 75 flight accidents occur in 2009 and 2017, wherein icing causes 8% of serious accidents, and 20% of common accidents cause huge loss.

At present, the traditional deicing methods include mechanical deicing, solution deicing and thermal deicing, and the methods have high energy consumption, low efficiency and short deicing duration and can cause influence on the environment. The novel deicing method achieves the purpose of deicing by mainly designing the special shape structure and chemical composition of the surface of the material, and has the characteristics of low energy consumption and high efficiency. The principle of the anti-icing coating is to remove the droplets that are not frozen on the surface by a weak external force before the supercooled droplets are frozen, thereby achieving the anti-icing effect. The existing super-hydrophobic coating has excellent anti-icing performance, the rolling of liquid drops can be effectively promoted by a larger contact angle and a smaller rolling angle, and the icing time of the liquid drops can be prolonged by the air cushion heat insulation effect of a micro-nano rough structure on the surface.

Patent application (CN101475173A) discloses that silver or gold nanoparticles are used as barriers to carry out chemical etching on the surface of a silicon chip to obtain a micron and nano composite structure surface, and then the composite surface is subjected to chemical modification and the like to obtain a super-hydrophobic surface, which has the defects of selectivity on the etched surface and needs chemical modification.A patent application (CN106521465A) discloses a three-level structure super-hydrophobic surface for anti-icing and a preparation method thereof, and the three-level structure super-hydrophobic surface has higher dynamic water repellency, the contact rebound time of impact liquid drops on the surface of the impact liquid drops is greatly reduced, but the mechanical property of the material is unstable, and the preparation process is complex.although the super-hydrophobic surface has an anti-icing effect of , the three-level structure super-hydrophobic surface still has two problems in practical use:

(1) the preparation process is complex, special equipment is often needed, the process is complicated, the material is selective, and the method is not suitable for preparing the super-hydrophobic coating in a large area;

(2) the super-hydrophobic durability of the coating is poor, resulting in a short life of the self-cleaning function of the coating.

Disclosure of Invention

Aiming at the defects of the existing super-hydrophobic coating, the invention provides super-hydrophobic coating composite materials for ice prevention and removal, which have good mechanical durability, can cope with almost hundred icing and ice removal circulation experiments, and show good self-cleaning performance and ice resistance in a wet and cold environment (15 ℃ below zero and relative humidity of 70%).

In addition, the invention also provides a preparation method of the super-hydrophobic coating composite material, which is simple and convenient, low in cost and strong in practicability, and overcomes the defects and application limitations of the existing deicing technology.

The above object of the present invention is achieved by the following technical solutions:

the super-hydrophobic coating composite material has a contact angle larger than 150 degrees, a thickness of 2-5 mu m, a rough concave-convex micro-nano structure on the surface, and is obtained by taking Polydimethylsiloxane (PDMS) as an adhesive, performing polymerization with ring-crosslinked polyphosphazene microspheres, and then dip-coating, brushing or spraying the adhesive on the surface of a substrate, wherein:

the mass ratio of the ring-crosslinked polyphosphazene microspheres to the PDMS is (1-3): 5;

the surface of the ring-crosslinked polyphosphazene microsphere is rich in-CF₃The average diameter of the radicals is 0.5 to 2 μm.

, the ring-crosslinked polyphosphazene microsphere is prepared by dissolving 0.40g of polyphosphazene (HCCP) (1.15mmol) and 1.16g of Bisphenol AF (BAF) (3.448mmol) in 80mL of acetonitrile in a dry single-neck round-bottom flask, adding 4mL of triethylamine, reacting in an ultrasonic water bath at 50 ℃ for 5h, washing the obtained reaction product with ethanol and deionized water three times respectively, and drying in vacuum at 60 ℃ to obtain white powder of the ring-crosslinked polyphosphazene microsphere.

The preparation method of the super-hydrophobic coating composite material comprises the following steps:

(1) sequentially carrying out ultrasonic cleaning on the surface of a base material to be treated by using an ethanol water solution and cleaning by using distilled water for at least times, and drying by using a 60-DEG C oven;

(2) and (2) mixing PDMS and a curing agent according to a mass ratio of 10: 1, dissolving in normal hexane, adding ring-crosslinked polyphosphazene microspheres, and sequentially performing ultrasonic dispersion for 15min and magnetic stirring for 1h to obtain PDMS/PHC dispersion liquid;

(3) and (2) dip-coating, brushing or spraying the PDMS/PHC dispersion liquid obtained in the step (1) on the surface of the base material treated in the step (1), and curing and reacting for 3h at 60 ℃.

, the solidifying agent contains polydimethylsiloxane as main component and Pt catalyst as effective component.

Compared with the prior art, the invention has the beneficial effects that:

(1) in the invention, the surface of the ring-crosslinked polyphosphazene microsphere is rich in-CF₃The group has good monodispersity and reactivity, forms a composite interface layer with the PDMS elastomer in a covalent bond mode, has good interface structure and a synergistic effect of a micron-scale surface structure, and the obtained super-hydrophobic coating composite material has lotus leaf super-hydrophobic self-cleaning performance, a contact angle of more than 150 degrees, good self-cleaning performance and anti-icing performance in a wet and cold environment (-15 ℃, relative humidity of 70 percent), long icing delay time, low adhesion after icing and good mechanical durability.

(2) The preparation method of the super-hydrophobic coating composite material can be carried out at room temperature, has mild conditions, does not need complex special equipment and subsequent treatment process, is suitable for large-area construction, and is easy to apply to the surfaces of different objects.

Drawings

FIG. 1 is a schematic process diagram of example 1.

FIG. 2 is the surface topography of the coating in example 1.

FIG. 3 is the water contact angle of the coating in example 4; wherein, (a, b) contact angle schematic; (c) the state of the coating in water; (d) water flow rebounding photos; (e) photographs of static water droplets on the surface of different substrates.

FIG. 4 is a stability test of the coating of the present invention; wherein, (a, b) a schematic diagram of a sandpaper abrasion test; (c) schematic diagram of knife scratch test; (d) performing an abrasion test using abrasive paper; (e) scratch test with finger and knife; (f) contacting a superhydrophobic coating composite coating with a hand; (g) contact angle and sliding angle of the material after multiple times of abrasion.

FIG. 5 is an anti-icing performance of the coating of the present invention; wherein, (a) a static anti-icing test; (b) dynamic anti-icing experiments; (c) ice adhesion strength of untreated aluminum sheets and superhydrophobic coating composite coated aluminum sheets.

Detailed Description

The following is a detailed description of the embodiments of the present invention, which is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

Preparation method of super-hydrophobic coating composite material

Step 1: in a dry, single-neck round-bottom flask, 0.40g of polyphosphazene (1.15mmol) and 1.16g of bisphenol AF (3.448mmol) were dissolved in 80mL of acetonitrile, 4mL of triethylamine was added to the solution, and the reaction was carried out in an ultrasonic water bath at 50 ℃ for 5 hours. After the reaction is finished, respectively washing the reaction product with ethanol and deionized water for three times, and performing vacuum drying at the temperature of 60 ℃ to obtain poly (cyclotriphosphazene-co-bisphenol AF) microspheres which are white powder, wherein the surfaces of the prepared phosphazene microspheres are rich in-CF (CF)₃The groups have better monodispersity and the average diameter is 0.5-2 mu m.

2, placing the surface of the substrate in an ethanol water solution, cleaning oil stains and dust on the surface by using ultrasonic waves, carrying out ultrasonic treatment for 10min, cleaning the surface by using distilled water for 3 times, transferring the surface to a 60 ℃ oven for drying for later use, dissolving quantitative PDMS and a curing agent in n-hexane, adding the prepared hydrophobic PHC microspheres, dispersing for 15min by using ultrasonic waves, stirring for 1h on a magnetic stirrer to obtain PDMS/PHC dispersion liquid, uniformly spraying the dispersion liquid on the surface of the pretreated material by adopting a dip-coating, brushing or spraying process, and placing the pretreated material in a physicochemical drying oven for heating, curing and crosslinking to obtain the PDMS/PHC coating.

Test method

1. Micro-morphology

A field emission scanning electron microscope (FE-SEM) photograph was taken at an acceleration voltage of 5kV by a JEOLJSM-7410F type field emission scanning electron microscope. Samples were prepared as follows: the porous coating film was cut to a specification of 2mm × 2mm, and then the sample was subjected to a metal spraying treatment.

2. Wetting Performance test

The hydrophobicity of the coating was reflected by the contact angle of water on the surface of the coating, as measured by a Dataphysics OCA20 contact angle test instrument. The contact angle of water on the surface of the coating measured by the contact angle measuring instrument reflects the hydrophobicity of the coating, and each sample is measured for 5 times at different positions and averaged.

3. Mechanical stability

The mechanical stability of the surface was evaluated by applying a finger scratch, sandpaper abrasion test and knife scratch test A200 mesh grit SiC sandpaper was used to perform a sandpaper abrasion test under a load of 50g and then pulled at a speed of 60mm/s in directions in 20cm increments until a final distance of 120cm was reached, testing the contact angle value during each abrasion test.

4. Anti-icing performance

The anti-icing performance of the coating is verified through icing delay time and ice adhesion measurement experiments. Static and dynamic anti-icing experiments using a home-made device to measure the droplets on the coating. The samples were placed on a stage by controlling the system temperature at-15 ℃ in an outdoor environment (70% RH), then 40 μ Ι _ of water droplets were placed on the surface to cool down, and the digital camera recorded the freezing process and time of the water droplets. The ice-removing performance of the composite material with high efficiency and long service life is illustrated by adopting a method of icing-deicing circulation that ice blocks are soaked in water and are still on the surface. The dynamometer is made of SH-500 with a mountain degree, the clamp is made of aluminum material, and the dynamometer is placed in a temperature control box in advance to be cooled to-25.0 ℃. The ice blocks used in the experiment are prepared in advance by using a mould and placed in a temperature control box for heat preservation, the temperature of purified water stained by the ice blocks is about 10 ℃ of the room temperature of a laboratory, and the ice blocks are favorable for controlling the temperature of water and avoiding freezing in the process of moving to the surface after being stained with water. The freezing time of each icing is about 3min, each deicing adopts a thrust gauge to horizontally align the center of an ice block to remove the ice block, and the force is recorded.

The following specific examples are used to prepare super-hydrophobic coating composite materials, and the performance tests are performed, further are used to explain the technical scheme of the present invention.

Example 1

Referring to fig. 1, 50mg of PDMS and 5mg of a curing agent were dissolved in n-hexane without PHC, and after ultrasonic dispersion for 15min, the PDMS dispersion was stirred on a magnetic stirrer for 1h to obtain a PDMS dispersion. The dispersion is uniformly sprayed on the surface of the pretreated glass by adopting a spraying process on a glass sheet, and then the glass sheet is placed in a physicochemical drying oven for curing reaction for 3 hours at 60 ℃ to obtain a PDMS coating, wherein the surface appearance is shown in figure 2. The measured contact angle of the droplet was 128 °, the rolling angle was 15 °, and the freezing delay time was 872 s.

Example 2

The mass ratio of PHC to PDMS was 0.2. Dissolving 50mg of PDMS and 5mg of curing agent in n-hexane, adding 10mg of hydrophobic PHC microspheres, ultrasonically dispersing for 15min, and stirring for 1h on a magnetic stirrer to obtain PDMS/PHC dispersion. And (3) uniformly distributing the dispersion liquid on the pretreated aluminum sheet by adopting a lifting process on the aluminum sheet, and placing the aluminum sheet in a physicochemical drying oven for curing reaction at 60 ℃ for 3 hours to obtain the PDMS/PHC coating composite material, wherein the measured contact angle of the liquid drop is 153 degrees, the rolling angle is 7.8 degrees, and the freezing delay time is 1029 s.

Example 3

The mass ratio of PHC to PDMS was 0.4. Dissolving 50mg of PDMS and 5mg of curing agent in n-hexane, adding 20mg of hydrophobic PHC microspheres, ultrasonically dispersing for 15min, and stirring for 1h on a magnetic stirrer to obtain PDMS/PHC dispersion liquid. The dispersion is uniformly coated on the surface of a pretreated steel material by adopting a brushing process, and the pretreated steel material is placed in a physicochemical drying oven for curing reaction for 3h at the temperature of 60 ℃ to obtain the PDMS/PHC coating composite material, wherein the measured contact angle of liquid drops is 160 degrees, the rolling angle is 3.9 degrees, and the icing delay time is 1398 s.

Example 4

The mass ratio of PHC to PDMS was 0.4. Dissolving 50mg of PDMS and 5mg of curing agent in n-hexane, adding 20mg of hydrophobic PHC microspheres, ultrasonically dispersing for 15min, and stirring for 1h on a magnetic stirrer to obtain PDMS/PHC dispersion. The dispersion is uniformly sprayed on the surface of the pretreated steel by adopting a spraying process, and then the surface is placed in a physicochemical drying oven for curing reaction for 3h at the temperature of 60 ℃ to obtain the PDMS/PHC coating composite material, wherein the measured contact angle of liquid drops is 164 degrees (as shown in figure 3), the rolling angle is 3.7 degrees, and the icing delay time is 1472 s.

As shown in fig. 3, the hydrophobicity of the coating can be visually reflected by the static contact angle of water on the surface of the coating, and the wettability of the super-hydrophobic coating composite material prepared in example 4 on different substrate surfaces is tested. It can be seen that the superhydrophobicity is mainly due to the nano-and micro-scale surface roughness and the low surface energy-CF₃Synergistic effect of the groups. The surface of the coated composite material shows excellent super-hydrophobicity, has a stable Cassie-Baxter state, and has a contact angle of 164 degrees and a rolling angle of 3.7 degrees (figures 3a and b). When the surface is immersed in water, the coating is covered by a layer of air with intense light reflection (fig. 3c), and a continuous stream of water dyed with methylene blue is able to bounce off completely at the surface (fig. 3 d). Meanwhile, the super-hydrophobic coating composite may be applied to various surfaces including aluminum substrates, stainless steel plates, paper and cotton (fig. 3e) in addition to the glass slide glass, and all have super-hydrophobicity, and thus, it can be known that the obtained super-hydrophobic coating composite may be applied to various surfaces.

Example 5

The mass ratio of PHC to PDMS was 0.6. Dissolving 50mg of PDMS and 5mg of curing agent in n-hexane, adding 30mg of hydrophobic PHC microspheres, ultrasonically dispersing for 15min, and stirring for 1h on a magnetic stirrer to obtain PDMS/PHC dispersion. The dispersion liquid is uniformly sprayed on the surface of a pretreated aluminum sheet by adopting a spraying process, and then the aluminum sheet is placed in a physicochemical drying oven for curing reaction for 3 hours at the temperature of 60 ℃ to obtain the PDMS/PHC coating composite material, wherein the measured contact angle of liquid drops is 157 degrees, the rolling angle is 5 degrees, and the icing delay time is 1276 s.

As shown in fig. 4, the mechanical stability of the superhydrophobic coating composite of the present invention was verified by performing finger scraping, sandpaper abrasion, and scraping tests according to general standards. In fig. 4e, it can be observed that the coated composite material still retains its superhydrophobicity in the area after being touched by a finger. Sandpaper abrasion test is an effective method of evaluating the mechanical abrasion resistance of superhydrophobic surfaces, using 200 mesh grit SiC sandpaper as a tool to abrade the surface, a sample of superhydrophobic-coated composite material of 50 grams or more is placed face down on the sandpaper and moved 20cm along the scale (fig. 4a, d), and then the sample is rotated 90 ° in the opposite direction (facing the sandpaper) and moved 20cm along the scale (fig. 4b, d) to ensure that the surface is abraded both longitudinally and transversely in each cycle. Fig. 4g shows the contact angle and the change in the sliding angle data for the superhydrophobic coating composite after multiple abrasions, and after 10 abrasion cycles, the contact angle was found to drop slightly from 160 ° to 156 ° and the sliding angle increased slightly from 3.7 ° to 8.6 °, but still not more than 10 °, indicating that the material remained superhydrophobic even after being abraded by sandpaper cycles. Furthermore, the knife scratch test schematic is shown in fig. 4c, using a knife to scrape the superhydrophobic coating composite along a red dashed path, it can be seen that the superhydrophobicity and self-cleaning performance of the superhydrophobic coating composite is well maintained after the knife test (fig. 4 f).

As shown in fig. 5, static and dynamic anti-icing experiments and icing-deicing cycle experiments of droplets on the superhydrophobic coating composite material according to the present invention were performed using a homemade apparatus, by controlling the system temperature at-15 ℃ in an outdoor environment (70% humidity), placing a sample on a stage, then placing 40 μ L of water droplets on the surface to cool down, a digital camera recording the freezing process and time of the water droplets, and verifying the anti-icing performance of the coating by the icing delay time, including:

1) the test of static deicing experiments compares the freezing delay time of single water drop dyed by methylene blue on the super-hydrophobic coating composite material coated aluminum sheet and the freezing delay time of pure aluminum sheet on a cooling table, ensures that the surface reaches-15 ℃ by controlling the temperature, and records the freezing delay time by shooting photos in the whole freezing process, as shown in fig. 5 a. It was found that on pure aluminum slides, the water droplets rapidly frozen after 7s, began to nucleate, and completely frozen at 28 s. The water drops on the surface of the super-hydrophobic coating composite material coated aluminum sheet begin to nucleate in 1231s and are completely frozen in 1472s, and the icing delay time is 50 times slower than that of the pure aluminum surface, so that the super-hydrophobic coating composite material has excellent anti-icing performance and still has good anti-icing performance in a large supercooling degree environment.

2) The dynamic anti-icing test verifies the anti-icing performance of the super-hydrophobic coating composite material, the super-hydrophobic coating composite material coated aluminum sheet and the pure aluminum sheet are inclined on a cooling platform at fixed angles, water drops drop on the surface, as shown in figure 5 b.

3) Icing-deicing cycle test the anti-icing performance and stability of the superhydrophobic coating composite material, the ice adhesion strength at-25 ℃ is shown in fig. 5c, the ice adhesion value on the surface of the pure aluminum sheet is 320kPa, and the ice adhesion strength on the superhydrophobic coating composite material coated aluminum sheet is 60 kPa. This is probably due to the low contact area of the liquid on the superhydrophobic surface with the substrate, so that the ice formed is loose and fluffy, resulting in a decrease of the adhesion strength of ice on the superhydrophobic coating composite coated aluminum sheet by a factor of nearly 5 compared to a pure aluminum surface.

Claims (6)

1. The super-hydrophobic coating composite material for preventing and removing ice is characterized in that the contact angle of the super-hydrophobic coating composite material is larger than 150 degrees, the thickness of the super-hydrophobic coating composite material is 2-5 microns, and the surface of the material has a rough concave-convex micro-nano structure, and the super-hydrophobic coating composite material is obtained by taking Polydimethylsiloxane (PDMS) as an adhesive, performing polymerization reaction with ring-crosslinked polyphosphazene microspheres , and then performing dip-coating, brushing or spraying on the surface of a base material.

2. The super-hydrophobic coating composite material according to claim 1, wherein the mass ratio of the ring-crosslinked polyphosphazene microspheres to the PDMS is 1-3: 5.

3. the superhydrophobic coating composite material of claim 1, wherein the surface of the ring-crosslinked polyphosphazene microsphere is rich in-CF₃The average diameter of the radicals is 0.5 to 2 μm.

4. The superhydrophobic coating composite material according to claim 1 or 3, wherein the ring-crosslinked polyphosphazene microsphere is prepared by the following method: in a dry, single-neck round-bottom flask, 0.40g of polyphosphazene (HCCP) (1.15mmol) and 1.16g of Bisphenol AF (BAF) (3.448mmol) were dissolved in 80mL of acetonitrile, 4mL of triethylamine were added, and the mixture was reacted for 5h in an ultrasonic water bath at 50 ℃; and washing the obtained reaction product with ethanol and deionized water for three times respectively, and drying in vacuum at 60 ℃ to obtain the white powder of the ring-crosslinked polyphosphazene microsphere.

5. A method for preparing the superhydrophobic coating composite of any of claims 1-4, comprising the steps of:

(1) sequentially carrying out ultrasonic cleaning on the surface of a base material to be treated by using an ethanol water solution and cleaning by using distilled water for at least times, and drying by using a 60-DEG C oven;

(2) and (2) mixing PDMS and a curing agent according to a mass ratio of 10: 1, dissolving in normal hexane, adding the ring-crosslinked polyphosphazene microspheres, and sequentially performing ultrasonic dispersion for 15min and magnetic stirring for 1h to obtain a PDMS/PHC dispersion solution;

(3) and (2) dip-coating, brushing or spraying the PDMS/PHC dispersion liquid obtained in the step (1) on the surface of the base material treated in the step (1), and curing and reacting for 3h at 60 ℃.

6. The method for preparing the super-hydrophobic coating composite material according to claim 5, wherein the curing agent comprises polydimethylsiloxane as a main component and a platinum catalyst as an effective component.

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