CN110373069B

CN110373069B - Hydrogel coating and preparation method and application thereof

Info

Publication number: CN110373069B
Application number: CN201810327418.1A
Authority: CN
Inventors: 郭倩; 贺志远; 吕健勇; 王健君
Original assignee: Institute of Chemistry CAS; University of Chinese Academy of Sciences
Current assignee: Institute of Chemistry CAS; University of Chinese Academy of Sciences
Priority date: 2018-04-12
Filing date: 2018-04-12
Publication date: 2021-03-05
Anticipated expiration: 2038-04-12
Also published as: CN110373069A

Abstract

The invention belongs to the technical field of surface processing and coating, and particularly relates to a hydrogel coating as well as a preparation method and application thereof. The hydrogel coating is formed by alternately coating different polyelectrolytes on the surface of a base material in a layer-by-layer assembly mode and preparing a polyelectrolyte network structure through chemical crosslinking, so that the aims of reducing the icing temperature and prolonging the icing time are fulfilled. The coating prepared by the invention has the characteristics of simple preparation process, wide application range, easiness in large-area construction, environmental friendliness, excellent anti-icing and anti-frost effects and the like.

Description

Hydrogel coating and preparation method and application thereof

Technical Field

The invention belongs to the technical field of surface processing and coating, and particularly relates to a hydrogel coating as well as a preparation method and application thereof.

Background

The icing phenomenon is widely present in nature, especially in a low-temperature and high-humidity environment. Icing in the fields of heat exchange, traffic, electric power, communication, aviation, national defense and the like often causes the problems of energy consumption improvement, efficiency reduction and the like, and can also form potential safety hazards and cause catastrophic accidents in severe cases. Therefore, the research and preparation of the anti-icing material have important significance on the safety of economy, society and national defense.

In addition to heating, ice protection of cold surfaces can take targeted measures before or after icing, respectively: preventing the accumulation of water droplets on cold surfaces or preventing the freezing of accumulated water droplets before freezing, and reducing the adhesion of the ice layer to the substrate to cause it to fall off after freezing, generally include spraying an ice inhibitor, performing surface treatment, or applying an anti-icing coating.

Patent CN102134475A discloses an anti-icing additive, wherein polyacrylate polyelectrolyte and copolymer of methacrylamide and methyl acrylate are mixed according to a certain proportion, chemical groups of polyacrylate can generate hydrogen bond action with ice crystals to be adsorbed on the surfaces of the ice crystals to inhibit the growth of the ice crystals, and the copolymer of methacrylamide and methyl acrylate improves the hydrophobic action of the additive and can effectively adsorb on the surfaces of the ice crystals to inhibit the growth of the ice crystals, thereby being an effective measure for preventing the recrystallization of binary ice solution. However, the ice formation inhibitor is usually an organic liquid, cannot exist stably for a long time, has a short action time, and requires repeated construction.

The Aizenberg group of Harvard university designs and prepares a super-hydrophobic surface with a micro-material structure, a nano structure or a micro-nano structure, water drops can rebound when colliding with the super-hydrophobic surface to avoid water from freezing after the water accumulates on the surface, and heat exchange between a substrate and the water drops can be inhibited to delay the freezing of the water drops on the surface. The patent CN105689236A discloses a method for preparing a superhydrophobic coating on an aluminum surface with a micro-nano composite structure based on this principle. However, the superhydrophobic surface can only have a certain degree of anti-icing effect when the temperature is not too low and the humidity is not too high, and the superhydrophobic surface has poor mechanical properties and is easy to damage so as to lose the anti-icing effect.

Patent CN101701131A discloses an intelligent active anti-icing coating material and a preparation method thereof, wherein the coating material comprises 10-60 wt% of temperature-sensitive phase-change material and 20-80 wt% of solvent, wherein the temperature-sensitive phase-change material is a block copolymer formed by polysiloxane and other polymers, but the structure and the preparation method are complex. The anti-icing coating generally acts by reducing the ice adhesion strength of the surface after icing and post-processing after icing, so improvement in initial anti-icing performance is required.

In summary, the conventional anti-icing methods generally have some limitations, so it is urgently needed to develop an anti-icing approach with easy construction, low energy consumption, high efficiency and no pollution.

Disclosure of Invention

In order to solve the defects of the prior art, the invention aims to provide a hydrogel coating and a preparation method and application thereof. Scientifically screening and reasonably matching polyelectrolytes with different electrical properties, alternately coating the polyelectrolytes on the surface of a base material in a layer-by-layer assembly mode in a spraying, brushing, spin coating and other modes, and forming a polyelectrolyte multilayer film with a specific thickness through electrostatic interaction, hydrogen bonds, base pairing interaction, charge transfer interaction or covalent bonds and the like among different polyelectrolytes; through chemical crosslinking, a part of polyelectrolyte forms a network structure, and then the uncrosslinked polyelectrolyte is extracted and removed, so that the hydrogel coating with remarkable anti-icing performance is obtained.

The purpose of the invention is realized by the following technical scheme:

the invention provides a hydrogel coating which is obtained by applying a chemical crosslinking method on the basis of a polyelectrolyte multilayer film.

According to the present invention, the polyelectrolyte is selected from one or more (e.g., two or more) of an anionic polyelectrolyte, a cationic polyelectrolyte, or an amphoteric polyelectrolyte.

According to the invention, the polyelectrolytes are chosen from weak polyelectrolytes.

According to the invention, the anionic polyelectrolyte is chosen from: poly (sodium 4-styrenesulfonate) (PSS), polyacrylic acid, polyacrylate, polymethacrylic acid (PMAA), polymethacrylate, polystyrenesulfonic acid, polyvinylsulfonic acid salt, polyvinylphosphoric acid, polyvinylphosphate, polyphosphate, polysilicate, negatively charged nucleic acid or protein, or the like.

Preferably, the anionic polyelectrolyte is selected from one or more (e.g., two or three) of poly (4-styrenesulfonate), polymethacrylic acid, and polystyrene sulfonate.

According to the invention, the cationic polyelectrolyte is chosen from: one or more (e.g., two or more) of polyvinylpyrrolidone (PVPON), polyethyleneimine salt, polyvinylamine salt, polyvinylpyridine salt, polyvinylamine salt, polyallylamine salt, polydiallyldimethylammonium salt, positively charged protein, and the like. According to the invention, the polyallylamine salt is preferably polyallylamine hydrochloride (PAH).

Preferably, the cationic polyelectrolyte is selected from one or more (e.g., two or three) of polyethyleneimine, polyvinylpyrrolidone, and polyallylamine hydrochloride.

According to the invention, the polyelectrolyte is a polyelectrolyte with functional groups.

According to the present invention, the functional group of the functional group-bearing polyelectrolyte is selected from at least one of epoxy group, amino group, carboxyl group, hydroxyl group, double bond, and the like.

According to the invention, the polyelectrolyte multilayer film is prepared by adopting a layer-by-layer self-assembly mode, and the polyelectrolyte multilayer film is assembled together by utilizing at least one of electrostatic attraction, hydrogen bonds, base pairing interaction, charge transfer interaction or covalent bonds.

According to the invention, the hydrogel coating is provided with counter ions. The counter ion is selected from Fe³⁺、Li⁺、Cu²⁺、NH₄ ⁺、Ag⁺、Ca²⁺、CTAB⁺(CTAB is cetyltrimethylammonium bromide, CTAB⁺Cetyl trimethylammonium ion) is added.

According to the invention, the hydrogel coating comprises a base layer and a primary coating.

According to the invention, the base layer is a multi-layer coating formed by alternately forming a cationic polyelectrolyte layer and an anionic polyelectrolyte layer from the substrate side to the outside in sequence, so as to enhance the adsorption force of the subsequent main coating.

According to the invention, the base layer is formed alternately in the following sequence of constituent units: a cationic polyelectrolyte layer/an anionic polyelectrolyte layer/a cationic polyelectrolyte layer; the number of said building blocks may be from 1 to 20, preferably from 2 to 7, for example from 2 to 5.

According to the invention, the anionic polyelectrolyte of the base layer is selected from poly (sodium 4-styrenesulfonate) (PSS) and the cationic polyelectrolyte of the base layer is selected from polyethyleneimine and/or polyallylamine hydrochloride (PAH).

According to the invention, the primary coating is a polyelectrolyte multilayer film formed by alternately forming an anionic polyelectrolyte layer, a cationic polyelectrolyte layer and a polyelectrolyte layer from the side of the cationic polyelectrolyte layer to the outside.

According to the invention, the cationic polyelectrolyte in the primary coating is different from the cationic polyelectrolyte in the base layer; the anionic polyelectrolyte in the primary coating is different from the anionic polyelectrolyte in the base layer.

According to the invention, the anionic polyelectrolyte of the primary coating is selected from polymethacrylic acid (PMAA) and the cationic polyelectrolyte of the primary coating is selected from polyvinylpyrrolidone (PVPON).

According to the invention, the main coating is formed alternately in succession with n constituent units as follows: an anionic polyelectrolyte layer/a cationic polyelectrolyte layer; denoted as n layers.

The n is 2 to 200, preferably 2 to 60, more preferably 2 to 40, and still more preferably 2 to 30.

For example, from the substrate side out, the composition of the hydrogel coating before crosslinking is:

PAH/PSS/PAH/PSS/PAH/PSS/PAH/PMAA/PVPON/PMAA … … PMAA/PVPO N/PMAA/PVPON … …, and the outermost layer is PVPON.

The invention also provides an anti-icing material comprising a substrate and a hydrogel coating on the surface of the substrate, the hydrogel coating having the above definition.

Wherein the substrate is selected from metal materials, non-metal materials, inorganic materials, organic materials, composite materials and the like, such as silicon, glass, copper, aluminum, iron, metal oxide materials, high polymer organic materials.

The invention also provides a preparation method of the hydrogel coating or the anti-icing material, which comprises the following steps: a step of preparing a polyelectrolyte multilayer film, and a step of chemical crosslinking.

Preferably, the preparation method specifically comprises the following steps:

(1) coating polyelectrolyte on the surface of a substrate in a layer-by-layer assembly mode to form a polyelectrolyte multilayer film;

(2) forming a three-dimensional network structure on part of polyelectrolyte by chemical crosslinking;

(3) the uncrosslinked polyelectrolyte is extracted and removed.

According to the invention, in step (1), the polyelectrolytes are preferably different polyelectrolytes; the different polyelectrolytes are coated alternately on the surface of the substrate.

The polyelectrolyte is preferably a polyelectrolyte with functional groups.

According to the invention, in the step (1), the layer-by-layer assembly is that different polyelectrolyte solutions are alternately coated on the surface of the substrate by soaking, spraying, brushing, spin coating and the like to form the polyelectrolyte multilayer film.

According to the invention, in step (1), the substrate has the above definition.

According to the present invention, in the step (2), a crosslinking agent may be added to the reaction.

The chemical crosslinking is a functional group of the polyelectrolyte, and reacts with a crosslinking agent under a specific acid-base environment to connect the polyelectrolytes in a chemical bond mode.

According to the invention, in the step (3), the extraction is the destruction of hydrogen bond action among different polyelectrolytes in a specific acid-base environment, and uncrosslinked polyelectrolytes fall off.

According to the invention, the preparation method specifically comprises the following steps:

1) preparing a cationic polyelectrolyte solution, an anionic polyelectrolyte solution, an activator solution and a cross-linking agent solution;

2) forming a coating of a corresponding cationic polyelectrolyte or anionic polyelectrolyte on a substrate with a cationic polyelectrolyte solution or an anionic polyelectrolyte solution;

3) forming a coating layer with opposite charges to the previous coating layer on the base material with the coating layer obtained in the step 2) by using an anionic polyelectrolyte solution or a cationic polyelectrolyte solution;

4) repeating the steps 2) and 3) until a target number of layers of coatings are obtained;

5) soaking the substrate with the polyelectrolyte coating in an activating agent solution for activation, and then soaking in a cross-linking agent solution for cross-linking;

6) soaking the whole material obtained in the step 5) in an alkaline solution, and extracting to remove one component;

7) soaking the whole material obtained in the step 6) in a counter ion solution to obtain the hydrogel coating with counter ions.

According to the invention, in step 1), the solvent of the anionic polyelectrolyte solution and the cationic polyelectrolyte solution is preferably water.

The activating agent is selected from 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC).

The cross-linking agent is one or two of ethylenediamine and glutaraldehyde.

The concentration of the anionic polyelectrolyte solution of the base layer is 0.5-1.5g/L, such as 1 g/L.

The concentration of the cationic polyelectrolyte solution of the base layer is 0.5-1.5g/L, such as 1 g/L.

The concentration of the anionic polyelectrolyte solution of the primary coating is in the range of 0.1 to 0.9g/L, for example 0.5 g/L.

The concentration of the cationic polyelectrolyte solution of the primary coating is 0.1-0.9g/L, such as 0.5 g/L.

The concentration of the activator solution is 2-8g/L, for example 5 g/L.

The concentration of the crosslinker solution is 2-8g/L, for example 5 g/L.

When preparing the polyelectrolyte solution, inorganic salts may be added to the solution, and the thickness of the coating produced may be adjusted by varying the concentration of the inorganic salts.

According to the invention, the concentration of the inorganic salt is between 0.001 and 4mol/L, for example 0.5 mol/L. The inorganic salt is preferably sodium chloride.

According to the invention, step 2) also comprises a step of pre-treatment of the substrate; the pretreatment steps of the base material are as follows: and (3) placing the base material in a mixed solution of concentrated sulfuric acid and hydrogen peroxide, and heating for a period of time until no bubbles are generated. After the solution was cooled to room temperature, the substrate was rinsed and dried.

When preparing the substrate layer, the step 2) is specifically as follows: and (3) soaking the treated base material in a cationic polyelectrolyte solution or an anionic polyelectrolyte solution, wherein the surface of the base material has positive charges or negative charges.

When preparing the substrate layer, the step 3) is specifically as follows: soaking the base material with the coating obtained in the step 2) in a polyelectrolyte solution with opposite charges to form a coating with opposite charges to the previous coating;

the time of soaking in said steps 2) and 3) may be the same or different, independently of each other, in the preparation of the substrate layer, selected from 5 to 15 minutes, for example 10 minutes.

In preparing the base layer, the steps 2) and 3) are repeated to obtain the target number of layers.

When the main coating is prepared, the step 2) is specifically as follows: and dripping the anionic polyelectrolyte solution or the cationic polyelectrolyte solution on the prepared integral material for coating, wherein the coating mode is spin coating.

When the main coating is prepared, the step 3) is specifically as follows: and dripping the polyelectrolyte solution with opposite charges on the prepared integral material for coating to form a coating with opposite charges to the previous coating, wherein the coating is spin-coated.

The spin coating speeds of said steps 2) and 3) may be the same or different in the preparation of the primary coating, independently of each other selected from the group consisting of 1000 and 4000 revolutions per second, such as 3000 revolutions per second.

In the preparation of the primary coating, the time of said spin coating of steps 2) and 3) may be the same or different, independently of each other, selected from 20 seconds to 40 seconds, for example 30 seconds.

In the preparation of the primary coating, the pH values of the anionic polyelectrolyte solution and the cationic polyelectrolyte solution may be the same or different, and are chosen independently of one another from 1 to 4, for example 2.5;

the pH of the polyelectrolyte solution may be adjusted by a phosphate buffer.

According to the invention, said steps 2) and 3) also comprise a step of washing the monolith after it has been removed from the polyelectrolyte solution.

In the preparation of the base layer, it is preferred to carry out rinsing with an inorganic salt solution, such as a sodium chloride solution. The time for flushing is 1-5 minutes. After the target number of layers of coating is achieved, it is preferably rinsed with deionized water.

In the preparation of the primary coating, rinsing with an acidic solution, for example phosphate buffer at pH 1-4, is preferred.

In step 5), the activation time is 5 to 65 minutes, preferably 10 to 60 minutes, for example 40 minutes.

The pH of the solution when activation is carried out is preferably 4.0 to 6.0, for example 5.0;

the pH of the solution may be adjusted by a phosphate buffer.

The crosslinking time is 3 to 29 hours, preferably 8 to 24 hours, for example 16 hours.

When crosslinking is performed, the pH of the solution is preferably 4.2 to 6.5, e.g. 5.8;

the pH of the solution may be adjusted by a phosphate buffer.

In step 6), the pH of the alkaline solution may be 7-9, e.g. 8.

The alkaline solution may be a phosphate buffer solution.

The soaking time may be 5 to 35 hours, preferably 10 to 30 hours, for example 24 hours.

In step 7), the counter ion solution is selected from an ammonium chloride solution, a silver nitrate solution, a lithium chloride solution, a copper chloride solution, an iron chloride solution, a calcium chloride solution, or a cetyltrimethylammonium bromide (CTAB) solution.

Preferably, the concentration of the counterion solution is 0.01-0.1mol/L, e.g., 0.01mol/L, 0.1 mol/L.

The soaking time is 15-25 hours, for example 19 hours.

The invention also provides application of the hydrogel coating or the anti-icing material, and the hydrogel coating or the anti-icing material can be used in the fields of electric power, traffic, communication or aviation, such as frost prevention of a heat exchanger, anti-icing of blades of a wind driven generator, anti-icing of vehicles, anti-icing of ships, anti-icing of surfaces of airplanes, anti-icing of electric power and communication facilities, and the like.

The invention has the advantages of

(1) The process is simple: the preparation method of the hydrogel coating is simple and easy to operate, and different polyelectrolytes can be alternately coated on the surface of the base material in a layer-by-layer assembly mode through spraying, brushing, spin coating and other modes, so that the hydrogel coating is formed through crosslinking.

(2) Wide application range and easy large-area construction: the hydrogel coating is excellent based on the preparation method and is suitable for being coated on the surfaces of various base materials, including metal materials, inorganic materials, organic materials, composite materials and the like.

(3) The performance is excellent: the hydrogel coating can effectively reduce the freezing temperature and prolong the freezing time, and has excellent anti-icing and anti-frost effects.

(4) Environmental protection property: the hydrogel coating disclosed by the invention is free of organic solvent in the preparation process, free of organic matter generation and loss in the application process, and green and environment-friendly.

Drawings

FIG. 1 is a schematic view of the sandwich structure of cover glass and O-ring for ice transfer time and ice nucleation according to the present invention;

FIG. 2 is a statistical plot of the freezing temperature of 0.1 μ L water droplets under 8-layer (PMAA) hydrogel coatings of different counterions using the experimental device shown in FIG. 1 as a sandwich device;

FIG. 3 is a statistical plot of freezing temperature for 0.1 μ L of water droplets at different numbers of layers of the cetyl trimethylammonium cation (PMAA) hydrogel coating, using the experimental device shown in FIG. 1 as a sandwich device;

FIG. 4 is a microscope photograph of condensed water before and after freezing on the surface of a hydrogel coating, wherein the experimental device is the device with the sandwich structure shown in FIG. 1;

FIG. 5 is a statistical plot of the ice transport time of condensed water under different counter ion coatings of 8-layer (PMAA) hydrogels, using the experimental device shown in FIG. 1 as a sandwich device.

Detailed Description

As previously mentioned, the present invention provides a hydrogel coating. The coating is a hydrogel coating formed by crosslinking a polyelectrolyte multilayer film assembled by two or more components. The polyelectrolyte multilayer film is formed by combining polyelectrolytes through certain interaction force including electrostatic interaction force, hydrogen bonds, coordination, charge transfer, molecular specificity recognition and the like. In a particular embodiment of the invention, the coating is held together by polyelectrolytes through hydrogen bonding and electrostatic interaction forces.

In the following examples, the "ice transit time" is the total time required from the freezing of the first water droplet to the freezing of the last water droplet, as observed by a microscope. The "freezing temperature" is a temperature at which a water droplet freezes, as observed by a microscope.

The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

The experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents, unless otherwise specified, are commercially available.

EXAMPLE 1 preparation of hydrogel coating

The hydrogel coating is obtained by applying a chemical crosslinking method on the basis of the polyelectrolyte multilayer film, the preparation of the polyelectrolyte multilayer film adopts a layer-by-layer self-assembly mode, and the polyelectrolyte multilayer film is assembled together by utilizing the electrostatic attraction and the hydrogen bond action of the polyelectrolyte.

Solutions of polyethyleneimine, poly (sodium 4-styrenesulfonate) (PSS) and polyallylamine hydrochloride (PAH) were prepared in a concentration of 1g/L with deionized water, respectively, and then sodium chloride was added to these solutions to give a concentration of 0.5 mol/L. Phosphate buffer solution with pH 2.5, 5.0 and 8 of 0.01mol/L is prepared by deionized water, and the pH and the ionic strength can be controlled and adjusted by 0.1mol/L hydrochloric acid solution and sodium hydroxide solution. Solutions of polymethacrylic acid (PMAA) and polyvinylpyrrolidone (PVPON) were prepared at a concentration of 0.5g/L using a phosphate buffer solution having a pH of 2.5, respectively. A 5g/L EDC solution was prepared using a phosphate buffer solution at pH 5.0. An ethylenediamine solution having a concentration of 5g/L was prepared from a phosphate buffer solution having an acid-base number in the range of 1 to 2, and the acid-base number of the solution was finally adjusted to 5.8.

(1) The silicon wafer is cut into the size of 1.8cm multiplied by 1.8cm, then placed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide (the volume ratio is 3:1), heated to 90 ℃ and kept for 30 minutes until no bubbles are generated (note: in the experiment, to ensure safety, the experiment must be carried out in a fume hood and concentrated sulfuric acid with high density must be added into the hydrogen peroxide solution). After the solution was cooled to room temperature, the mixed solution was poured into a designated waste liquid bottle, rinsed 3 times with a large amount of ultrapure water, and blown dry with nitrogen for use (it was stored in ultrapure water before use).

(2) And (3) soaking the treated silicon wafer in a polyethyleneimine solution for 10 minutes, and washing the silicon wafer for 1 minute by using a 0.5mol/L sodium chloride solution, wherein the surface of the silicon wafer has positive charges. Then, the sample was immersed in the PSS solution for 10 minutes to make the surface negatively charged, and washed with 0.5mol/L NaCl solution for 1 minute. The silicon wafer with the negative charge PSS coating was then immersed in the PAH solution for 10 minutes and rinsed with 0.5mol/L NaCl solution for 1 minute, which was recorded as one cycle. The circulation process is repeated for 3 times, and finally the PAH solution is soaked in the PAH solution for 10 minutes, so that the outermost layer is a PAH layer, the PAH layer is washed by deionized water for 1 minute, and the PAH layer is dried by nitrogen. At this point the base layer treatment is complete.

(3) 0.4mL of PMAA solution was dropped onto the substrate-bearing silicon wafer and applied by spin coating, followed by spin coating at 3000 rpm for 30 seconds and rinsing twice with phosphate buffer at pH 2.5 for 30 seconds. 0.4mL of PVPON solution was dropped onto a PMAA coated silicon wafer, spin coated at 3000 rpm for 30 seconds, and rinsed twice with phosphate buffer at pH 2.5 for 30 seconds to form a polyelectrolyte multilayer PMAA/PVPON, noted as 1 layer.

(4) The above process (3) is repeated until the desired number of layers n is reached.

(5) The coated substrate material obtained in step (4) was immersed in the EDC solution for 40 minutes and rinsed with deionized water for 30 seconds. Then soaked in ethylenediamine solution with gentle stirring for 16 hours and rinsed with deionized water for 30 seconds.

(6) And (3) soaking the integral material obtained in the step (5) in a phosphate buffer solution with the pH value of 8 for 24 hours to remove the PVPON coating, soaking the integral material in the phosphate buffer solution with the pH value of 5 for 15 minutes, washing the integral material with deionized water for 1 minute, and drying the integral material with nitrogen.

(7) Deionized water is used for preparing 0.1mol/L ammonium chloride, silver nitrate and lithium chloride solution and 0.01mol/L cupric chloride, ferric chloride, calcium chloride and Cetyl Trimethyl Ammonium Bromide (CTAB) solution. The hydrogel-coated silicon wafer obtained in step (6) was placed in each of these counter ion solutions for 19 hours in two pieces, rinsed with deionized water for 30 seconds, and blown dry with nitrogen.

The polyelectrolyte multilayer film coating obtained in the step (4) is marked as "PMAA/PVPON", and the final hydrogel coating obtained is marked as "(PMAA)_nR "is used generally in the following examples.

EXAMPLE 2 freezing temperature of Water droplets on hydrogel coating surface

7 types of 8-layer coatings "(PMAA) were prepared in the manner of example 1₈-Li”，“(PMAA)₈-NH₄”，“(PMAA)₈-Ag”,“(PMAA)₈-Cu”,“(PMAA)₈-Ca”,“(PMAA)₈-Fe”,“(PMAA)₈CTAB sample, using a micro-injector to drop 9-12 drops of 0.1 μ L water drops on the surface of the sample, then putting the sample into a sandwich structure shown in figure 1, placing the sample on a cold table, cooling at a rate of 5 ℃/min, observing and recording the freezing temperature of the water drops, repeatedly measuring 200 water drops, and calculating the average value and counting the data (shown in figure 2). The result shows that the difference of the freezing temperature of the surface of the sample with different counter ions is about 10 ℃ at most; coating "(PMAA)₈The freezing temperature of the-CTAB "sample was lowest compared to the others, around-24 ℃.

Therefore, the change of the water drop freezing temperature within 10 ℃ can be realized by changing the chemical composition of the hydrogel coating, namely the counter ion type.

EXAMPLE 3 Effect of coating thickness on coating icing temperature

Prepared in 7 thicknesses according to the method of example 1Hydrogel coating with cetyl trimethylammonium bromide ion "(PMAA)₂-CTAB”，“(PMAA)₄-CTAB”，“(PMAA)₆-CTAB”，“(PMAA)₈-CTAB”，“(PMAA)₁₀-CTAB”，“(PMAA)₂₀-CTAB”，“(PMAA)₃₀CTAB "sample, using a microsyringe, 9-12 drops of 0.1. mu.L water drops on the surface of the sample, then placing the sample in a sandwich structure as shown in FIG. 1, placing on a cold stage, cooling at a rate of 5 ℃/min, observing and recording the freezing temperature of the water drops. The freezing temperature of the water droplets on each sample was recorded, and 100-200 water droplets were repeatedly measured to obtain an average value and statistical data (shown in FIG. 3).

As a result, it was found that: coating at different thicknesses "(PMAA)_nThe samples of CTAB are all low in freezing temperature ranging from-24 ℃ to (-28 ℃).

It can be seen that the coating thickness has little effect on the freezing temperature of the hydrogel coating with cetyltrimethylammonium bromide ions.

Example 4 Ice transport time of condensed Water on different hydrogel coating surfaces

7 types of 8-layer coatings "(PMAA) were prepared according to the method of example 1₈-Li”，“(PMAA)₈-NH₄”，“(PMAA)₈-Ag”,“(PMAA)₈-Cu”,“(PMAA)₈-Ca”,“(PMAA)₈-Fe”,“(PMAA)₈-CTAB sample, put into sandwich structure, 4 drops of 0.2 μ L water drop are dropped on the glass sheet of the bottom layer, heated to 50 deg.C, kept for 3 minutes, condensed to 5 deg.C, then cooled at 5 deg.C/min, observed and recorded with high speed camera the whole process of freezing water drop on the surface of the visual field. The time to freeze the first water drop was recorded as 0ms and recorded using a high speed camera. Fig. 4 is a picture of condensed water before and after freezing in a microscope field. The ice transfer time of the condensed water on each sample was counted and plotted in fig. 5, to investigate the effect of hydrogel coatings with different counterions on the ice transfer time of the condensed water.

As a result, it was found that: coating "(PMAA)₈Ag "all condensed water on the surface of the sample freezes within 10s, while in the coating" (PMAA)₈-NH₄"the freezing time of all condensed water on the surface of the sample is about 60 s.

It can be seen that the hydrogel coating surfaces with different counterions have an effect on the ice transport time of the condensed water, with a maximum difference of about a dozen times.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A hydrogel coating, wherein the hydrogel coating comprises a base layer and a primary coating layer;

the base layer is a polyelectrolyte multilayer film formed by a cationic polyelectrolyte layer, an anionic polyelectrolyte layer and the like from the side of the base material to the outside in turn;

the main coating is a polyelectrolyte multilayer film formed by sequentially and alternately arranging an anionic polyelectrolyte layer and a cationic polyelectrolyte layer from the side of the cationic polyelectrolyte layer to the outside;

the cationic polyelectrolyte in the primary coating is different from the cationic polyelectrolyte in the base layer; the anionic polyelectrolyte in the primary coating is different from the anionic polyelectrolyte in the base layer;

the hydrogel coating is obtained by applying a chemical crosslinking method on the basis of a polyelectrolyte multilayer film;

the anionic polyelectrolyte is selected from: one or more of poly (sodium 4-styrenesulfonate) (PSS), polyacrylic acid, polyacrylate, polymethacrylic acid (PMAA), polymethacrylate, polystyrenesulfonic acid salt, polyvinylsulfonic acid salt, polyvinylphosphoric acid, polyvinylphosphate, polyphosphate, polysilicate, negatively charged nucleic acids or proteins;

the cationic polyelectrolyte is selected from: one or more of polyvinylpyrrolidone (PVPON), polyethyleneimine salt, polyvinylamine salt, polyvinylpyridine salt, polyvinylamine salt, polyallylamine salt, polydiallyldimethylammonium salt, positively charged protein;

the polyelectrolyte multilayer film is prepared by adopting a layer-by-layer self-assembly mode, and is assembled together by utilizing at least one of electrostatic attraction, hydrogen bonds, base pairing interaction, charge transfer interaction or covalent bonds of the polyelectrolyte.

2. The hydrogel coating of claim 1, wherein the hydrogel coating is provided with a counter ion; the counter ion is selected from Fe³⁺、Li⁺、Cu²⁺、NH₄ ⁺、Ag⁺、Ca²⁺、CTAB⁺One or more of (a).

3. The hydrogel coating of claim 1, wherein the anionic polyelectrolyte is selected from one or more of poly (4-sodium styrene sulfonate), polymethacrylic acid, polystyrene sulfonate.

4. The hydrogel coating of claim 1, wherein the cationic polyelectrolyte is selected from one or more of polyethyleneimine, polyvinylpyrrolidone, polyallylamine salts.

5. The hydrogel coating of claim 4, wherein the polyallylamine salt is polyallylamine hydrochloride (PAH).

6. The hydrogel coating of claim 1, wherein the polyelectrolyte is a functional group-bearing polyelectrolyte; the functional group of the polyelectrolyte with functional groups is selected from at least one of epoxy group, amino group, carboxyl group, hydroxyl group and double bond.

7. The hydrogel coating of claim 1, wherein the anionic polyelectrolyte of the base layer is selected from poly (sodium 4-styrenesulfonate) (PSS) and the cationic polyelectrolyte of the base layer is selected from polyethyleneimine and/or polyallylamine hydrochloride (PAH).

8. Hydrogel coating according to claim 1 or 7, wherein the anionic polyelectrolyte of the primary coating is selected from polymethacrylic acid (PMAA) and the cationic polyelectrolyte of the primary coating is selected from polyvinylpyrrolidone (PVPON).

9. The hydrogel coating of claim 1, wherein the primary coating is formed alternately in sequence as n constituent units of: an anionic polyelectrolyte layer/a cationic polyelectrolyte layer; recording as n layers;

and n is 2-200.

10. The hydrogel coating of claim 1,

from the substrate side out, the composition of the hydrogel coating before crosslinking is:

PAH/PSS/PAH/PSS/PAH/PSS/PAH/PMAA/PVPON/PMAA/PVPON … … PMA A/PVPON/PMAA/PVPON, and the outermost layer is PVPON.

11. An anti-icing material, characterized in that the anti-icing material comprises a substrate and a hydrogel coating on the surface of the substrate;

the substrate is selected from a metallic material, a non-metallic material, an inorganic material, an organic material, and a composite material;

the hydrogel coating is as defined in any one of claims 1 to 10.

12. The anti-icing material of claim 11, wherein said substrate is selected from the group consisting of silicon, glass, copper, aluminum, iron, metal oxide materials, high molecular polymer organic materials.

13. A method of preparing the hydrogel coating of any one of claims 1 to 10 or the anti-icing material of claim 11 or 12, the method comprising: a step of preparing a polyelectrolyte multilayer film, and a step of chemical crosslinking.

14. The method according to claim 13, characterized in that it comprises the steps of:

(1) coating polyelectrolyte on the surface of a base material in a layer-by-layer assembly mode to form a polyelectrolyte multilayer film, wherein the polyelectrolyte multilayer film sequentially comprises a polyelectrolyte multilayer film forming a base layer and a polyelectrolyte multilayer film forming a main coating;

(3) the uncrosslinked polyelectrolyte is extracted and removed.

15. The method of claim 14,

in the step (1), the polyelectrolytes are different polyelectrolytes; the different polyelectrolytes are alternately coated on the surface of the substrate;

the polyelectrolyte is a polyelectrolyte with functional groups;

in the step (1), the layer-by-layer assembly is that different polyelectrolyte solutions are alternately coated on the surface of a base material by soaking, spraying, brushing or spin coating to form a polyelectrolyte multilayer film;

in the step (2), the chemical crosslinking is a functional group of the polyelectrolyte, and the functional group reacts with a crosslinking agent in a specific acid-base environment to connect the polyelectrolytes in a chemical bond form;

in the step (3), the extraction is the destruction of hydrogen bond action among different polyelectrolytes in a specific acid-base environment, and uncrosslinked polyelectrolytes fall off.

16. The method according to claim 13, characterized in that it comprises the steps of:

17. The method according to claim 16, wherein in step 1), the solvent of the anionic polyelectrolyte solution and the cationic polyelectrolyte solution is water; and/or the presence of a gas in the gas,

the activating agent is selected from 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC); and/or the presence of a gas in the gas,

the cross-linking agent is selected from one or two of ethylenediamine and glutaraldehyde; and/or the presence of a gas in the gas,

the concentration of the anionic polyelectrolyte solution of the substrate layer is 0.5-1.5 g/L; and/or the presence of a gas in the gas,

the concentration of the cationic polyelectrolyte solution of the substrate layer is 0.5-1.5 g/L; and/or the presence of a gas in the gas,

the concentration of the anionic polyelectrolyte solution of the main coating is 0.1-0.9 g/L; and/or the presence of a gas in the gas,

the concentration of the cationic polyelectrolyte solution of the main coating is 0.1-0.9 g/L; and/or the presence of a gas in the gas,

the concentration of the activating agent solution is 2-8 g/L; and/or the presence of a gas in the gas,

the concentration of the cross-linking agent solution is 2-8 g/L; and/or the presence of a gas in the gas,

when preparing the polyelectrolyte solution, adding inorganic salt into the solution; the concentration of the inorganic salt is 0.001-4 mol/L; the inorganic salt is sodium chloride.

18. The method of claim 16, wherein step 2) further comprises a step of pre-treating the substrate; the pretreatment steps of the base material are as follows: placing the base material in a mixed solution of concentrated sulfuric acid and hydrogen peroxide, and heating for a period of time until no bubbles are generated; after the solution was cooled to room temperature, the substrate was rinsed and dried.

19. The method according to claim 16, wherein, in preparing the substrate layer, step 2) is specifically: and (3) soaking the treated base material in a cationic polyelectrolyte solution or an anionic polyelectrolyte solution, wherein the surface of the base material has positive charges or negative charges.

20. The method according to claim 16, wherein, in preparing the substrate layer, step 3) is specifically: soaking the base material with the coating obtained in the step 2) in a polyelectrolyte solution with opposite charges to form a coating with opposite charges to the previous coating.

21. The method according to claim 16, wherein the soaking time of the steps 2) and 3) is the same or different and is selected from 5 to 15 minutes independently from each other when preparing the substrate layer.

22. The method of claim 16, wherein steps 2) and 3) are repeated to obtain a target number of layers in preparing the substrate layer.

23. The method according to claim 16, wherein in preparing the primary coating, step 2) is embodied as: and dripping the anionic polyelectrolyte solution or the cationic polyelectrolyte solution on the prepared integral material for coating, wherein the coating mode is spin coating.

24. The method according to claim 16, wherein in preparing the primary coating, step 3) is in particular: and dripping the polyelectrolyte solution with opposite charges on the prepared integral material for coating to form a coating with opposite charges to the previous coating, wherein the coating is spin-coated.

25. The method as claimed in claim 24, wherein the spin coating speed in steps 2) and 3) is the same or different and is selected from 1000-.

26. The method according to claim 24, wherein the spin coating time of steps 2) and 3) is the same or different and is independently selected from 20 seconds to 40 seconds.

27. The method according to claim 16, wherein the pH values of the anionic polyelectrolyte solution and the cationic polyelectrolyte solution are the same or different and are selected from 1 to 4 independently of each other in preparing the primary coating.

28. The method of claim 16, wherein the pH of the polyelectrolyte solution is adjusted by a phosphate buffer.

29. The method of claim 16, wherein steps 2) and 3) further comprise the step of rinsing the monolith after it is removed from the polyelectrolyte solution.

30. The method of claim 16, wherein the base layer is prepared by rinsing with an inorganic salt solution; the flushing time is 1-5 minutes; after the target number of layers of coating was obtained, it was rinsed with deionized water.

31. The method of claim 16, wherein the primary coating is prepared by rinsing with an acidic solution.

32. The method of claim 16, wherein in step 5), the activation time is 5-65 minutes.

33. The method of claim 16, wherein the solution, when activated, has a pH of 4.0 to 6.0;

the pH of the solution was adjusted by phosphate buffer.

34. The method of claim 16, wherein the time for crosslinking is 3 to 29 hours;

the pH of the solution is 4.2-6.5 when crosslinking is performed;

the pH of the solution was adjusted by phosphate buffer.

35. The method according to claim 16, wherein in step 6), the pH of the alkaline solution is 7-9;

the alkaline solution is phosphate buffer solution;

the soaking time is 5-35 hours.

36. The method according to claim 16, wherein in step 7), the counter ion solution is selected from the group consisting of an ammonium chloride solution, a silver nitrate solution, a lithium chloride solution, a copper chloride solution, an iron chloride solution, a calcium chloride solution, and a cetyltrimethylammonium bromide (CTAB) solution.

37. The method of claim 16, wherein the concentration of the counterion solution is 0.01-0.1 mol/L;

the soaking time is 15-25 hours.

38. Use of the hydrogel coating according to any one of claims 1 to 10 or the anti-icing material according to claim 11 or 12, wherein the hydrogel coating or the anti-icing material is used in the fields of electricity, traffic, communication, aviation.

39. Use according to claim 38 for frost protection of heat exchangers, ice protection of wind turbine blades, ice protection of vehicles, ice protection of ships, ice protection of aircraft surfaces, ice protection of power and communication installations.