A fluorine-containing modified organopolysilazane, and a preparation method and application thereof

Abstract

This invention discloses a fluorinated modified organopolysilazane, its preparation method, and its applications. The fluorinated modified organopolysilazane is prepared by alcoholysis reaction of the organopolysilazane and a fluorinated alcohol monomer. The fluorinated modified organopolysilazane is chemically bonded to the substrate surface to form a firmly bonded protective film. The fluorinated polysilazane coating formed by hydrolysis in air exhibits hydrophobicity, resistance to high and low temperatures, scratch resistance, rainproofing, anti-fogging, and self-cleaning properties.

Description

Technical Field

[0001] This invention relates to a fluorinated modified organopolysilazane, specifically to a fluorinated alcohol monomer-modified organopolysilazane, its preparation method, and its application; belonging to the field of polymer preparation technology. Background Technology

[0002] Polysilazanes, polymers whose main chain consists of Si-N bonds, are important precursors for the preparation of Si-C-N ceramics. The bond angle difference between Si and N atoms (Δθ = 23°) is smaller than that between Si and O atoms (Δθ = 36°), therefore, compared to polysiloxanes, they have a lower tendency to form rings and are easier to modify substituents. Furthermore, the numerous Si-N bonds in the polysilazane molecule readily undergo hydrolysis, ultimately reacting with the -OH groups on the substrate surface to form a stable Si-O-Si structure. This results in excellent adhesion and anchoring properties of the cured polysilazane coating. Therefore, as a ceramic precursor, polysilazanes can be used to construct coatings with excellent heat resistance, chemical corrosion resistance, weather resistance, scratch resistance, and transparency, thus endowing polysilazane coatings with superior performance and a longer service life.

[0003] However, most polysilazane molecules contain only a small number of hydrophobic groups, which is insufficient to meet the hydrophobic performance requirements of coatings. Therefore, it is necessary to modify the polysilazane used as the coating substrate with low surface energy materials. Among these, fluorinated organic compounds are widely used for hydrophobic modification.

[0004] Currently, research has explored the application of hydrophobically modified organopolysilazanes in the field of hydrophobic coatings. Chinese invention patent application CN 105385349A discloses a hydrophobic and antifouling organopolysilazane coating and its preparation method. This method uses perfluoroalkyl ethyl allyl ether to hydrophobically modify polysilazane via a hydrosilylation reaction, producing a high-performance hydrophobic self-cleaning coating. However, the synthesis reaction system of the fluorinated perfluoroalkyl ethyl allyl ether used in this method is complex, the product requires purification, the process is cumbersome, and the synthesis cost is high. Furthermore, the hydrosilylation reaction between perfluoroalkyl ethyl allyl ether and organopolysilazane must be carried out in the presence of a catalyst, and the catalyst residue in the product is difficult to remove, which can negatively impact the product's performance. Summary of the Invention

[0005] The purpose of this invention is to provide a fluorinated modified organopolysilazane and its preparation method. The preparation method is simple, and the coating prepared with the fluorinated modified organopolysilazane can be converted into a hydrophobic coating under air conditions, which has waterproof and self-cleaning effects.

[0006] To achieve the above objectives, the present invention provides a fluorine-modified organopolysilazane with the following structure:

[0007]

[0008] Wherein, the side groups R1, R2, R3, and R4 on the main chain are organic groups or hydrogen atoms, wherein the organic groups are straight-chain or branched alkyl, alkenyl, alkynyl, or other groups containing 1 to 5 carbon atoms. R8 is a straight-chain alkylene group containing 1 to 4 carbons, and R5, R6 and R7 are straight-chain alkyl groups containing 1 to 4 carbons; m is an integer from 6 to 12, and n is an integer from 1 to 5.

[0009] This invention provides a method for preparing the above-mentioned fluorinated modified organopolysilazane, comprising: a step of preparing the fluorinated modified organopolysilazane by reacting a fluorinated alcohol monomer and the organopolysilazane in a solvent under the protection of an inert gas.

[0010]

[0011] Preferably, the general structural formula of fluorinated alcohol monomers is as follows: Where m is an integer from 6 to 12, preferably 6 to 8; n is an integer from 1 to 5, preferably 2 to 3.

[0012] Preferably, the structural formula of the organopolysilazane is as follows: Wherein, the side groups R1, R2, R3, and R4 on the main chain are organic groups or hydrogen atoms; the organic groups are straight-chain or branched alkyl, alkenyl, alkynyl, or other groups containing 1 to 5 carbon atoms. R8 is a straight-chain alkylene group containing 1 to 4 carbons, while R5, R6, and R7 are straight-chain alkyl groups containing 1 to 4 carbons.

[0013] Preferably, the inert gas is nitrogen or argon.

[0014] Preferably, the solvent is at least one or a combination of tetrahydrofuran, toluene, xylene, ethylbenzene, n-hexane, n-octane, n-decane, cyclohexane, ethyl acetate, butyl acetate, tert-butyl acetate, diethyl ether, n-butyl ether, petroleum ether, acetone, methyl ethyl ketone, and ethyl ethyl ketone.

[0015] Preferably, the mass ratio of fluorinated alcohol monomer to organopolysilazane is 1:1 to 1:100, more preferably 1:1 to 1:40.

[0016] Preferably, the amount of solvent used is 3 to 20 times the total mass of the fluorinated alcohol monomer and the organopolysilazane, more preferably 3 to 10 times.

[0017] Preferably, the alcoholysis reaction temperature is 20–60°C, and more preferably 30–50°C.

[0018] Preferably, the alcoholysis reaction time is 2 to 12 hours, and more preferably 6 to 10 hours.

[0019] Preferably, the solvent is removed by vacuum evaporation at 40-90°C after the alcoholysis reaction.

[0020] In addition, the present invention provides a hydrophobic coating comprising the above-mentioned fluorinated modified organopolysilazane.

[0021] Preferably, it also includes a solvent, which is at least one or a combination of tetrahydrofuran, toluene, xylene, ethylbenzene, n-hexane, n-octane, n-decane, cyclohexane, ethyl acetate, butyl acetate, tert-butyl acetate, diethyl ether, n-butyl ether, petroleum ether, acetone, methyl ethyl ketone, and ethyl ethyl ketone.

[0022] Preferably, the concentration of fluorinated modified organopolysilazane in the hydrophobic coating is 1–60 wt%, more preferably 10–40 wt%.

[0023] Finally, the present invention provides a stable and durable hydrophobic coating and its preparation method, which is obtained by coating the above-mentioned hydrophobic coating on the surface of a substrate and then curing it.

[0024] Preferably, the coating is applied by methods such as drip casting, dip coating, spraying, spin coating, scraping, roller coating, or brushing, with spraying being the preferred method.

[0025] Preferably, the substrate is one of inorganic non-metallic materials, metallic materials, polymeric materials and composite materials with one-dimensional, two-dimensional or three-dimensional structures, with glass being the most preferred.

[0026] Preferably, curing refers to curing at a temperature of 60–200°C for 0.5–5 hours, and more preferably at a temperature of 80–120°C for 1–3 hours.

[0027] Preferably, the water contact angle of the hydrophobic coating is 103° to 108°.

[0028] In summary, the method for synthesizing fluorine-modified organopolysilicon nitride disclosed in this invention, and the method for applying it as a durable hydrophobic coating on a substrate surface, have four characteristics:

[0029] (1) Fluorine-modified organopolysilazane imparts good adhesion between polymer coatings and substrates such as glass, overcoming the limitation of poor adhesion to substrate materials that is common in low surface energy coatings, making fluorinated polysilazane a hydrophobic agent with good durability.

[0030] (2) Fluorine-modified organopolysilazane is transformed into a polysiloxane structure under the action of air moisture, forming a uniform and dense semi-inorganic coating while maintaining good interfacial bonding force, thus overcoming the problem that low surface energy coatings are difficult to wet and spread on high polarity glass surfaces.

[0031] (3) Compared with common hydrosilylation reactions, the modified reaction used in this invention does not require the use of catalysts or other auxiliaries. The reaction can still be carried out under mild and simple reaction conditions, and the product does not require post-processing, which greatly improves production efficiency.

[0032] (4) The traditional method of using multi-component blending to resolve the contradiction between substrate wettability and coating hydrophobicity is abandoned. Instead, precursor technology is used to achieve the unity of the two. The modified organopolysilazane in this invention has wide applicability and is suitable for various substrate surfaces, such as glass, plastics, metals and ceramics. Attached Figure Description

[0033] Figure 1 The image shows the Fourier transform infrared (FT-IR) spectra of the perfluorooctylpropanol-modified organopolysilazane and its reactants, namely perfluorooctylpropanol (PFOP) and organopolysilazane (OPSZ), prepared in Example 1.

[0034] Figure 2 The 1H NMR spectra of the perfluorooctylpropanol-modified organopolysilazane and its reactants, namely perfluorooctylpropanol (PFOP) and organopolysilazane (OPSZ), prepared in Example 1 are shown. 1 H-NMR spectrum.

[0035] Figure 3 Thermogravimetric analysis (TGA) diagram of the perfluorooctylpropanol modified organopolysilazane coating constructed on the surface of a glass substrate in Example 2.

[0036] Figure 4 Images of water droplets in contact with the glass surface obtained when measuring the water contact angle of the perfluorooctylpropanol modified organopolysilazane coating constructed on the glass substrate surface in Example 2.

[0037] Figure 5 Images of water droplets in contact with a glass surface obtained when measuring the water contact angle of an unmodified organopolysilazane coating.

[0038] Figure 6 Images of water droplets in contact with a glass surface obtained when measuring the water contact angle on a blank glass surface.

[0039] Figure 7 Images of water droplets in contact with the glass surface obtained when measuring the water contact angle of the perfluorohexylethanol-modified organopolysilazane coating constructed on the glass substrate surface in Example 4. Detailed Implementation

[0040] The following are embodiments of the present invention, but the present invention is not limited to the following embodiments. Any non-substantial improvements made using the concept and technical solutions of the present invention, or direct application of the technology of the present invention without modification, are within the scope of the claims of the present invention.

[0041] This invention provides a method for preparing the above-mentioned fluorine-modified organopolysilazane, the method comprising the following steps;

[0042] (1) Under the protection of an inert gas, fluorinated alcohol monomers and organopolysilazanes are added to a solvent and stirred until homogeneous;

[0043] (2) After the alcoholysis reaction is carried out at a temperature of 20 to 60°C for 2 to 12 hours, the solvent in the reaction system is removed by vacuum evaporation to obtain fluorine-modified organopolysilazane.

[0044] The alcoholysis reaction for preparing fluorine-modified organopolysilazanes is shown in reaction formula (1):

[0045]

[0046] Example 1: Preparation of perfluorooctylpropanol-modified organopolysilazane

[0047] The air in a pre-dried 25 mL Schlenk reaction tube was evacuated three times to remove air and moisture. Under nitrogen protection, 2.00 g of organopolysilazane (OPSZ) and 15.0 mL of solvent THF were added sequentially, and the mixture was stirred at 600 rpm until homogeneous. Then, 0.8 g of perfluorooctylpropanol (PFOP) was added, and the flask was protected with a nitrogen balloon. The temperature was raised to 50 °C, and the reaction system was allowed to react at 50 °C with stirring for 10 h. Heating was then stopped to terminate the reaction. The solvent in the reaction system was removed by rotary evaporation, yielding a semi-transparent liquid, perfluorooctylpropanol-modified organopolysilazane OPSZ-PFOP-40%.

[0048] The structure of the organic polysilazane used in this embodiment is as follows:

[0049]

[0050] Figure 1 The image shows the Fourier Transform Infrared (FT-IR) spectra of the perfluorooctylpropanol-modified organopolysilazane and its reactants, namely perfluorooctylpropanol (PFOP) and organopolysilazane (OPSZ), prepared in Example 1. The υ(NH) stretching vibration peak corresponds to 3383 cm⁻¹. -1 The stretching vibration peak of υ(CH) corresponds to 2961 cm⁻¹. -1 The stretching vibration peak of υ(Si-H) corresponds to 2120 cm⁻¹. -1 The δ(Si-CH3) bending vibration absorption peak corresponds to 1251 cm⁻¹. -1 The δ(NH) bending vibration absorption peak corresponds to 1161 cm⁻¹. -1 The υ(Si-N) stretching vibration peak corresponds to 890 cm⁻¹ -1The υ(OH) stretching vibration peak of PFOP corresponds to 3322 cm⁻¹. -1 However, it did not appear in the infrared absorption spectrum of OPSZ-PFOP-40%, indicating that the PFOP involved in the reaction had been fully utilized. Simultaneously, OPSZ-PFOP-40% was observed to have an absorption spectrum at 1199 cm⁻¹. -1 The appearance of the υ(CF) stretching vibration peak at the point also proves that the modification of OPSZ was successful.

[0051] Figure 2 The 1H NMR spectra of the perfluorooctylpropanol-modified organopolysilazane and its reactants, namely perfluorooctylpropanol (PFOP) and organopolysilazane (OPSZ), prepared in Example 1 are shown. 1 H-NMR spectrum. Comparison with PFOP. 1 The H-NMR spectrum shows that OPSZ-PFOP-40% 1 In the 1H-NMR spectrum, no proton peaks at 4.03-4.08 ppm were observed at this range, indicating that the hydroxyl groups in the PFOP molecule had completely participated in the reaction and disappeared. Meanwhile, OPSZ-PFOP-0.4... 1 In the H-NMR spectrum, C belonging to PFOP also appeared. H 2-O (δ=3.74), C H 2-CF2 (δ=2.18), CH2-C H The peak at 2 (δ=1.85) proves that the OPSZ modification was successful.

[0052] Example 2: Application of perfluorooctylpropanol-modified organopolysilazane

[0053] 0.05 g of the perfluorooctylpropanol modified organopolysilazane OPSZ-PFOP-40% prepared in Example 1 was dissolved in 1 mL of ethyl acetate solvent and mixed evenly to obtain an OPSZ-PFOP-40% solution with a mass fraction of 4.8 wt%. Then, using glass and tinplate as substrates, the prepared OPSZ-PFOP-40% solution was coated onto the substrate surface by spraying technology and allowed to heat-cur at 120°C for 2 hours to obtain perfluorooctylpropanol modified organopolysilazane OPSZ-PFOP-40% coatings constructed on different substrate surfaces, which were denoted as OPSZ-PFOP-40%@Glass and OPSZ-PFOP-40%@SPTE, respectively.

[0054] Figure 3The thermogravimetric analysis (TGA) curve shows the OPSZ-PFOP-40%@Glass coating constructed on a glass substrate in Example 2. From the TGA curve, the weight loss of the thermosetting OPSZ-PFOP-40% before 363°C mainly comes from the release of NH3 and H2 during the thermosetting process; the thermal crosslinking reaction occurs below 350°C; between 350 and 790°C, an organic-to-inorganic transformation occurs, after which the TGA curve flattens out, and the ceramic pyrolysis yield at 790°C is 65.3%.

[0055] Figure 5 , Figure 6 and Figure 7 Images showing the contact angle of water droplets with different surfaces obtained when measuring the water contact angle of the OPSZ-PFOP-40%@Glass coating constructed on a glass surface used as a substrate in Example 2, as well as the unmodified organopolysilazane OPSZ@coated Glass and blank glass surfaces as controls. Figure 7 The test results showed that the water contact angle on the blank glass surface was only 45.2°, classifying it as a hydrophilic surface; while Figure 5 OPSZ-PFOP-40%@Glass coating constructed on glass substrate and Figure 6 The water contact angles of the unmodified organopolysilazane OPSZ@Glass coatings were 106.1° and 95.6°, respectively, both exhibiting hydrophobicity, with the OPSZ-PFOP-40%@Glass coating showing more significant hydrophobicity.

[0056] Example 3: Preparation of organopolysilazane modified with perfluorohexylethanol

[0057] The air in a pre-dried 25 mL Schlenk reaction tube was evacuated three times to remove air and moisture. Under nitrogen protection, 2.00 g of organopolysilazane (OPSZ) and 15.0 mL of solvent THF were added sequentially, and the mixture was stirred at 600 rpm until homogeneous. Then, 0.6 g of perfluorohexylethanol (PFHE) was added, and the tube was protected with a nitrogen balloon. The temperature was raised to 50 °C, and the reaction system was allowed to react at 50 °C with stirring for 10 h. Heating was then stopped to terminate the reaction. The solvent in the reaction system was removed by rotary evaporation, yielding a semi-transparent liquid, perfluorohexylethanol-modified organopolysilazane OPSZ-PFHE-30%.

[0058] The structure of the organopolysilazane used in this embodiment is as follows:

[0059]

[0060] Example 4: Application of perfluorohexylethanol-modified organopolysilazane

[0061] 0.05 g of the perfluorohexyl ethanol modified organopolysilazane OPSZ-PFHE-30% prepared in Example 3 was dissolved in 1 mL of ethyl acetate solvent and mixed evenly to obtain an OPSZ-PFHE-30% solution with a mass fraction of 4.8 wt%. Then, using glass and tinplate as substrates, the prepared OPSZ-PFHE-30% solution was coated onto the substrate surface by spraying technology and allowed to heat-cur at 120°C for 2 hours to obtain perfluorohexyl ethanol modified organopolysilazane OPSZ-PFHE-30% coatings constructed on different substrate surfaces, which were denoted as OPSZ-PFHE-30%@Glass and OPSZ-PFHE-30%@SPTE, respectively.

[0062] Figure 7 Images of water droplets in contact with the coating surface were obtained when measuring the water contact angle of the OPSZ-PFHE-30%@Glass coating constructed on a glass surface used as a substrate in Example 4. According to... Figure 6 The test results showed that the water contact angle on the blank glass surface was only 45.2°, classifying it as a hydrophilic surface; while Figure 7 OPSZ-PFHE-30%@Glass coating constructed on glass substrate and Figure 5 The water contact angles of the unmodified organopolysilazane OPSZ@Glass coatings were 104.6° and 95.6°, respectively, both exhibiting hydrophobicity, with the OPSZ-PFHE-30%@Glass coating showing stronger hydrophobicity.

Claims

1. A method for preparing fluorine-modified organopolysilazane, characterized in that, The structure of the fluorine-modified organopolysilazane is shown in the following formula: ； The side groups R1, R2, R3, and R4 on the main chain are organic groups or hydrogen atoms, wherein the organic groups are straight-chain or branched alkyl, alkenyl, alkynyl, or other groups containing 1 to 5 carbon atoms. R8 is a straight-chain alkylene group containing 1 to 4 carbons, and R5, R6 and R7 are straight-chain alkyl groups containing 1 to 4 carbons; m is an integer from 6 to 12, and n is an integer from 1 to 5. The steps include: preparing fluorinated modified organopolysilazane by undergoing an alcoholysis reaction of fluorinated alcohol monomers and organopolysilazanes in a solvent under the protection of an inert gas. .

2. The method as described in claim 1, characterized in that, Fluorinated alcohol monomers In this context, m is 6-8; n is 2-3.

3. The method as described in claim 1, characterized in that, The mass ratio of fluorinated alcohol monomers to organopolysilazanes is 1:1 to 1:

100.

4. The method as described in claim 1, characterized in that, The mass ratio of fluorinated alcohol monomers to organopolysilazanes is 1:1 to 1:

40.

5. The method as described in claim 1, characterized in that, The alcoholysis reaction temperature is 20~60℃; the alcoholysis reaction time is 2~12h.

6. The method as described in claim 1, characterized in that, The alcoholysis reaction temperature is 30~50℃; the alcoholysis reaction time is 6~10h.

7. A hydrophobic coating, characterized in that, It comprises fluorinated modified organopolysilazane prepared by the method as described in any one of claims 1-6.

8. The hydrophobic coating as described in claim 7, characterized in that, It also contains a solvent, which is at least one or a combination of tetrahydrofuran, toluene, xylene, ethylbenzene, n-hexane, n-octane, n-decane, cyclohexane, ethyl acetate, butyl acetate, tert-butyl acetate, diethyl ether, n-butyl ether, petroleum ether, acetone, methyl ethyl ketone and ethyl ethyl ketone.

9. The hydrophobic coating as described in claim 7, characterized in that, In hydrophobic coatings, the concentration of fluorinated modified organopolysilazane is 1~60wt%.

10. The hydrophobic coating as described in claim 7, characterized in that, In hydrophobic coatings, the concentration of fluorinated modified organopolysilazane is 10~40wt%.

11. A stable and durable hydrophobic coating, characterized in that, It is obtained by applying the hydrophobic coating as described in any one of claims 7-10 to the surface of a substrate and then curing it.

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