Preparation method of BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating

Abstract

The invention relates to a preparation method of a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating, which comprises the following steps: dissolving NH2-PDMS-NH2 and terephthalaldehyde in 20ml of DMF (Dimethyl Formamide) solution, and carrying out polymerization reaction in a nitrogen atmosphere to prepare I-PDMS; adding IPDI (isophorone diisocyanate), and carrying out polymerization reaction in a nitrogen atmosphere, so as to prepare HI-PDMS; then adding PBA, and carrying out a polymerization reaction in a nitrogen atmosphere to prepare a polymer BHI-PDMS; the synthesized BHI-PDMS and nano SiO2 are mixed and then sprayed to form a fluoride-free, moisture-absorption, self-repairing, super-hydrophobic and highly transparent coating, the problem that transparency becomes poor due to introduction of a repairing agent when the self-repairing and super-hydrophobic coating is prepared is solved, the self-repairing and super-hydrophobic coating can be conveniently applied to various optical devices, the surfaces of the materials are endowed with long-acting self-cleaning and waterproof capabilities, and the self-cleaning and waterproof properties of the surfaces of the materials are improved. And the transparency of the material is reserved.

Description

Technical Field

[0001] The present invention relates to the technical field of super hydrophobic coatings, and in particular to a BHI-PDMS / SiO 2 Preparation method of self-repairing super-hydrophobic transparent coating. Background Art

[0002] Super-hydrophobic surface is a common phenomenon in nature, which refers to the state where the static contact angle of water droplets on the solid surface is more than 150° and the rolling angle is less than 10°. Super-hydrophobic coating materials have unique self-cleaning, anti-corrosion, anti-fouling and anti-fogging, anti-icing and anti-dust and other important properties. They have broad application prospects in the fields of self-cleaning and anti-fouling, oil-water separation, anti-fogging, anti-icing, anti-corrosion, biomedicine, surface patterning, new transportation equipment, etc.

[0003] The super-hydrophobicity of the material surface is the result of the combined effect of the chemical composition of the material surface and the surface microstructure. Therefore, the super-strong hydrophobicity of the material surface can be achieved by changing the chemical composition of the material surface, such as introducing low surface free energy substances, or constructing a surface micro-nano multi-level structure. However, in practical applications, super-hydrophobic coating materials are inevitably affected by external environments such as chemical corrosion, scratches and wear, resulting in the loss of super-hydrophobicity. Existing super-hydrophobic self-cleaning coatings are generally compounded formula products. The introduction of repair agents will cause the transparency of the coating to deteriorate, so further improvement is needed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a BHI-PDMS / SiO 2 Preparation method of self-repairing super-hydrophobic transparent coating.

[0005] The present invention is achieved through the following technical solutions:

[0006] A BHI-PDMS / SiO 2 A method for preparing a self-repairing super-hydrophobic transparent coating comprises the following steps:

[0007] S1. NH 2 -PDMS-NH 2 and terephthalaldehyde were dissolved in 20 ml of DMF solution, and polymerization was carried out under nitrogen atmosphere to obtain the preliminary polymer I-PDMS;

[0008] S2. IPDI was added to the I-PDMS solution, and polymerization was carried out under a nitrogen atmosphere to obtain a polymer HI-PDMS;

[0009] S3. PBA was added to the HI-PDMS solution, and polymerization was carried out under a nitrogen atmosphere to obtain a polymer BHI-PDMS;

[0010] S4. The synthesized BHI-PDMS and nano-SiO 2 After mixing, spray coating was performed to form BHI-PDMS / SiO 2 Self-healing superhydrophobic transparent coating.

[0011] According to the above technical solution, preferably, in step S1, 1 mmol NH 2 -PDMS-NH 2 and 0.5mmol terephthalaldehyde were dissolved in 20ml DMF solution.

[0012] According to the above technical solution, preferably, in step S2, 1 mmol IPDI is added to the I-PDMS solution.

[0013] According to the above technical solution, preferably, in step S3, 1 mmol PBA is added to the HI-PDMS solution.

[0014] According to the above technical solution, preferably, in steps S1-S3, the polymerization reaction is carried out under a nitrogen atmosphere for 24 hours.

[0015] According to the above technical solution, preferably, in step S4, the concentration of the BHI-PDMS is 0.25-0.7 mg / ml.

[0016] According to the above technical solution, preferably, in step S4, the BHI-PDMS and nano-SiO 2 The total concentration of the two substances was controlled to a maximum of 0.5 mg / ml.

[0017] According to the above technical solution, preferably, in step S4, the BHI-PDMS and nano-SiO 2 The mass ratio is (0.5-1.5):1.

[0018] According to the above technical solution, preferably, in step S4, the synthesized BHI-PDMS and nano-SiO 2 After mixing, spray it in 10-30 layers.

[0019] According to the above technical solution, preferably, in step S4, the substrate is placed on a heating platform for spraying, the distance between the nozzle and the substrate is fixed at 10-15 cm, and the single spraying amount does not exceed 0.1 m / cm 2 After spraying, drying is carried out.

[0020] The beneficial effects of the present invention are:

[0021] The present invention forms a supramolecular polymer having three reversible dynamic chemical bonds (imine bond, hydrogen bond, nitrogen coordinated boron oxygen bond) through polymerization reaction between specific functional groups. The dynamic chemical bonds of the supramolecular polymer can be quickly repaired after being damaged, and simultaneously play multiple roles in the coating, such as transparent coating building blocks, hydrophobic agent, adhesive, and repair agent, thereby solving the problem of poor transparency caused by the introduction of repair agents when preparing self-repairing super-hydrophobic coatings.

[0022] At the same time, SiO 2 The nanoparticles and BHI-PDMS supramolecular polymer were sprayed on the substrate to obtain a new fluorine-free, hygroscopic self-healing superhydrophobic, highly transparent coating, which can be conveniently applied to various optical devices, giving the surface of these materials long-lasting self-cleaning and waterproof capabilities while retaining the transparency of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the chemical reaction in the preparation process of the present invention.

[0024] Figure 2 BHI-PDMS / SiO sprayed on PC board 2 Coating in O 2 Digital images of contact angle test before and after plasma etching and the change of contact angle sliding angle with repair time.

[0025] Figure 3 Graph showing the relationship between the number of sprayed layers and the contact angle in the present invention.

[0026] Figure 4 The different solute concentrations in the present invention have an effect on the BHI-PDMS / SiO 2 Schematic diagram of the influence of superhydrophobicity of coating and transmittance of visible light at 550 nm (T550).

[0027] Figure 5 The BHI-PDMS and nano-SiO 2 The mass ratio of BHI-PDMS / SiO 2 Schematic diagram of the effects of coating hydrophobicity and light transmittance. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and the best embodiment. Based on the embodiments in the invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the invention.

[0029] like Figure 1 As shown, the present invention comprises the following steps:

[0030] S1. NH 2 -PDMS-NH 2 and terephthalaldehyde were dissolved in 20 ml of DMF solution, and polymerization was carried out under a nitrogen atmosphere to obtain a preliminary polymer I-PDMS.

[0031] Specifically, in this example, it is preferred to add 1 mmol NH 2 -PDMS-NH 2 and 0.5 mmol of terephthalaldehyde were dissolved in 20 ml of DMF solution and transferred to a round-bottom flask. The polymerization reaction was carried out for 24 hours under a nitrogen atmosphere to obtain a preliminary polymer I-PDMS. This step is to achieve the reaction between the amino group and the aldehyde group so that the molecular chain segment contains a dynamic chemical bond, an imine bond.

[0032] S2. Add IPDI to the I-PDMS solution and perform polymerization reaction under a nitrogen atmosphere to obtain a polymer HI-PDMS.

[0033] Specifically, in this example, 1 mmol IPDI is preferably added to the I-PDMS solution, and the polymerization reaction is carried out for 24 hours under a nitrogen atmosphere to obtain the polymer HI-PDMS. This step is to achieve the reaction between the amino group and the isocyanate group so that the molecular chain segments contain dynamic chemical bonds and hydrogen bonds.

[0034] S3. PBA is added to the HI-PDMS solution, and a polymerization reaction is carried out under a nitrogen atmosphere to obtain a polymer BHI-PDMS.

[0035] Specifically, in this example, 1 mmol of PBA is preferably added to the HI-PDMS solution, and the polymerization reaction is carried out for 24 hours under a nitrogen atmosphere to obtain the polymer BHI-PDMS. This step is to achieve the reaction between the amino group and the isocyanate group in PBA so that the molecular chain segment contains a nitrogen-coordinated boron-oxygen bond.

[0036] The chemical bond contains two hydroxyl groups that can form a dynamic chemical bond boron oxygen hexacyclic ring between molecular chains. When the coating is destroyed, the super hydrophobicity of the coating is also destroyed, and water molecules can enter. When the nitrogen coordinated boron oxygen bond is destroyed, its two hydroxyl groups are exposed. The entry of water molecules acts as a medium to generate hydrogen bond forces with the hydroxyl groups, accelerating the collision and combination between the nitrogen coordinated boron oxygen bonds, thereby accelerating the self-repair process and restoring the super hydrophobic state. Therefore, by introducing the cross-linking effect of the nitrogen coordinated boron oxygen hexacyclic ring, when the self-repairing material in the coating is destroyed, the hydrophobicity becomes worse, and water molecules are more likely to enter, so that the self-repairing material can achieve active moisture absorption to enhance the self-repairing ability.

[0037] S4. The synthesized BHI-PDMS and nano-SiO 2After mixing, spray coating was performed to form BHI-PDMS / SiO 2 Self-healing superhydrophobic transparent coating.

[0038] Specifically, in this example, it is preferred to combine the synthesized BHI-PDMS with nano-SiO 2 (SiO with a particle size of 7 nm 2 Nanoparticles, concentration 0.175 mg / ml) were mixed and sprayed, and added to anhydrous ethanol at a ratio of (0.5-1.5):1 (the preferred mass ratio in this example is 1:1), BHI-PDMS and nano-SiO 2 The total concentration of the two substances was controlled at a maximum of 0.5 mg / ml. The substrate was then placed on a heating platform at 50°C for spraying. The distance between the nozzle and the substrate was fixed at 12 cm. The number of spray layers was 10-30 (15 layers were preferred in this example). The working pressure of the spray gun was 0.24 MPa. The amount of each spray was controlled at 0.1 ml / cm 2 , repeat the spraying process until the required number of spraying cycles is reached. After the substrate is sprayed, it is dried at 60°C for 12 hours.

[0039] The final product of the self-healing material prepared in the present invention, BHI-PDMS, is a light yellow viscoelastic body (water contact angle is about 120.2°±0.2), has good transparency, and the selected hydrophobic nano-silica particle size is about 7nm, which is smaller than the wavelength range of visible light and can be transmitted, so the transparency of the coating is also less affected. Mixing BHI-PDMS and hydrophobic nano-silica in a certain proportion and spraying them has more advantages in coating transparency and adhesion performance than the traditional method of introducing a repair agent.

[0040] The dynamic covalent bonds of the supramolecular polymer prepared in the present invention can be reversibly opened under moisture stimulation, so that the PDMS segments have better mobility and the transparent self-healing super-hydrophobic coating can be reversibly opened under moisture stimulation. 2 After plasma etching, it can spontaneously and repeatedly repair its superhydrophobic properties under mild conditions. 2After plasma etching, the coating surface will have hydrophilic oxygen-containing functional groups, making the coating super-hydrophilic. However, after a certain period of self-repair, the coating can be restored to a super-hydrophobic state. The repair principle is that the BHI-PDMS molecular chain contains three reversible dynamic chemical bonds (imine bonds, hydrogen bonds, and nitrogen-coordinated boron-oxygen bonds). When the coating is damaged, these dynamic chemical bonds can be recombined under the movement of the molecular chain to achieve a self-repair effect. Moreover, the BHI-PDMS molecular chain segments can also accelerate the movement between molecular chains through the interaction between hydrogen bonds and between hydrogen bonds and surface hydrophilic groups, thereby covering the hydrophilic groups on the coating surface to accelerate the self-repair process and restore the super-hydrophobic state.

[0041] like Figure 2 As shown, Figure 2 (a) and (b) are the BHI-PDMS / SiO sprayed on PC board. 2 Coating in O 2 The digital images of the contact angle test before and after plasma etching and the contact angle sliding angle change with the repair time. After the coating was plasma etched, the contact angle decreased from 157.3°±0.5° to 0°. After 9 hours of recovery, the contact angle recovered to 156.8°±0.5°, and the sliding angle changed from 2.7°±0.2° to super hydrophobic, and then recovered to 2.8±0.2°. All these show that when the super hydrophobicity of the coating is damaged, it has good self-repairing properties and can be restored to a super hydrophobic state within a certain period of time.

[0042] like Figure 3 As shown, with the increase of the number of spray layers, the water contact angle of the coating continues to increase, which means that the hydrophobicity is enhanced. When the coating reaches a certain thickness, the contact angle rises more and more slowly, which is caused by the accumulation of silica particles.

[0043] In addition, this application also discloses the effects of different process parameters on the BHI-PDMS / SiO 2 The super hydrophobicity and transmittance of visible light at 550 nm (T550) of the coating. 2 The influence of super hydrophobicity and transmittance of visible light at 550 nm (T550) on the coating is shown in Figure 2. Figure 4As shown in the figure, as the concentration of the coating solution increases, the super hydrophobicity of the coating weakens. This is because, under the condition of ensuring the same spraying capacity, the high-concentration spraying solution is easy to agglomerate as the solvent evaporates after spraying, and it is impossible to form a uniform concave-convex structure on the surface. The transmittance increases slightly because the nano-silicon dioxide partially agglomerates, and the porosity increases due to uneven distribution, and the light transmittance increases. The low-concentration solution has the most uniform distribution, the smallest porosity, and the best super hydrophobicity, but there is a certain loss in transmittance. Therefore, the optimal concentration is screened out as 0.5mg / ml.

[0044] BHI-PDMS and Nano-SiO 2 The mass ratio of BHI-PDMS / SiO 2 The influence of coating hydrophobicity and light transmittance is as follows Figure 5 As shown in the figure, when the mass ratio of BHI-PDMS and nano-SiO2 is reduced to 0.5:1.0, the transparency of the coating decreases, but the superhydrophobicity increases. 2 The higher the content of BHI-PDMS, the easier it is to form a concave-convex surface structure, which improves the super-hydrophobicity of the coating. 2 When the mass ratio of BHI-PDMS increases to 1.5:1.0, the light transmittance of the coating increases, but the superhydrophobicity decreases. This is because the effect of BHI-PDMS on light transmittance is greater than that of SiO 2 Therefore, the light transmittance is enhanced. 2 The mass ratio of is preferably 1:1.

[0045] The present invention forms a supramolecular polymer with three reversible dynamic chemical bonds (imine bond, hydrogen bond, nitrogen coordinated boron oxygen bond) through polymerization reaction between specific functional groups. The supramolecular polymer dynamic chemical bonds can be quickly repaired after being damaged, and play multiple roles in the coating, such as transparent coating building blocks, hydrophobic agent, adhesive, and repair agent, thereby solving the problem of poor transparency caused by the introduction of repair agents when preparing self-repairing super hydrophobic coatings. At the same time, SiO 2 The nanoparticles and BHI-PDMS supramolecular polymer were sprayed on the substrate to obtain a new fluorine-free, hygroscopic self-healing superhydrophobic, highly transparent coating, which can be conveniently applied to various optical devices, giving the surface of these materials long-lasting self-cleaning and waterproof capabilities while retaining the transparency of the material.

[0046] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating, characterized in that: The following steps are involved: S1. NH2-PDMS-NH2 and terephthalaldehyde were dissolved in 20 ml of DMF solution and polymerized under a nitrogen atmosphere to obtain a preliminary polymer I-PDMS; S2. IPDI was added to the I-PDMS solution, and polymerization was carried out under a nitrogen atmosphere to obtain a polymer HI-PDMS; S3. PBA was added to the HI-PDMS solution, and polymerization was carried out under a nitrogen atmosphere to obtain a polymer BHI-PDMS; S4. The synthesized BHI-PDMS is mixed with nano-SiO2 and then sprayed to form a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating.

2. A method for preparing a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating according to claim 1, characterized in that: In step S1, 1 mmol NH2-PDMS-NH2 and 0.5 mmol terephthalaldehyde were dissolved in 20 ml DMF solution.

3. The method for preparing a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating according to claim 2, characterized in that: In step S2, 1 mmol IPDI is added to the I-PDMS solution.

4. The method for preparing a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating according to claim 3, characterized in that: In step S3, 1 mmol of PBA is added to the HI-PDMS solution.

5. The method for preparing the BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating according to any one of claims 1 to 4, characterized in that: In steps S1-S3, the polymerization reaction is carried out under a nitrogen atmosphere for 24 hours.

6. The method for preparing a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating according to claim 4, characterized in that: In step S4, the concentration of the BHI-PDMS is 0.25-0.7 mg / ml.

7. The method for preparing a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating according to claim 6, characterized in that: In step S4, the total concentration of the two substances, BHI-PDMS and nano-SiO2, is controlled at a maximum of 0.5 mg / ml.

8. A method for preparing a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating according to claim 7, characterized in that: In step S4, the mass ratio of BHI-PDMS to nano-SiO2 is (0.5-1.5):

1.

9. The method for preparing a BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating according to claim 4, characterized in that: In step S4, the synthesized BHI-PDMS is mixed with nano-SiO2 and then sprayed, and the number of spray layers is 10-30 layers.

10. The method for preparing the BHI-PDMS / SiO2 self-repairing super-hydrophobic transparent coating according to any one of claims 6 to 9, characterized in that: In step S4, the substrate is placed on a heating platform for spraying, the distance between the nozzle and the substrate is fixed at 10-15 cm, and the amount of spraying per time does not exceed 0.1 m / cm 2 After spraying, drying is carried out.

Images