Polysilazane containing perfluorinated branched short chain and preparation method thereof

Abstract

The invention discloses polysilazane containing a perfluorinated branched short chain and a preparation method of the polysilazane. The method comprises the following steps: (1) under the protection of inert gas, adding chlorosilane and a perfluorinated branched short-chain compound into a solvent for reaction to obtain a fluorine-containing chlorosilane monomer; and (2) adding a fluorine-containing chlorosilane monomer and a chlorosilane monomer into a solvent, and carrying out ammonolysis reaction under the protection of inert gas to prepare the fluorine-containing polysilazane. According to the invention, a perfluorinated branched short chain is introduced into polysilazane, so that the polysilazane is endowed with the characteristic of low surface energy, and meanwhile, the problems of toxicity and biological accumulation caused by a long-chain perfluorinated chain segment are avoided.

Description

Technical Field

[0001] The invention relates to a polysilazane based on perfluorinated branched short chain modification and a preparation method thereof, belonging to the field of polymer materials. Background Art

[0002] Polysilazane is a type of polymer material with Si-N bond as the main chain. Its molecular formula can be expressed as [R 1 R 2 Si-NR] n , where n is the degree of polymerization, R 1 and R 2 Represents the side chain substituent, usually a hydrogen atom, a methyl group or other organic group. This special molecular structure gives polysilazanes unique chemical properties. According to the different side chain substituents, polysilazanes can be mainly divided into two categories: inorganic polysilazanes and organic polysilazanes. The side chain substituents of inorganic polysilazanes are only hydrogen atoms, which can be used as precursors for preparing ceramic bulk materials, ceramic fibers, ceramic porous materials and ceramic coatings when cracked at high temperatures. Organic polysilazanes, by introducing organic groups, improve the flexibility of the overall polymer and significantly reduce the temperature required for coating curing, thus achieving a breakthrough close to large-scale industrial applications. In addition, since the coating has high density after curing of polysilazane, it can effectively protect structural components at a micron-level thickness through modification of different active groups, showing important application value in metal anti-corrosion, anti-fouling, anti-oxidation, wear resistance, self-cleaning and flame retardancy.

[0003] In view of the wide application potential of polysilazane in multiple fields, researchers continue to explore the development of different types of polysilazane materials. For example, by selecting different raw materials or performing later chemical modification, polysilazanes containing different organic groups are synthesized. Among them, fluorine-containing materials may produce new materials significantly different from traditional polysilazanes due to their excellent high and low temperature resistance, heat resistance and chemical resistance. 3M Company (CN201080029784) discloses a method for preparing organic fluorine-modified polysilazanes by reacting fluorine-containing compounds with polysilazanes. This method mainly relies on the reaction of the active sites of polysilazanes with fluorine-containing organic compounds, so the types of polysilazanes prepared by it are subject to certain restrictions. In addition, the Institute of Chemistry of the Chinese Academy of Sciences (CN201610891761) successfully prepared more types of fluorine-containing polysilazanes by modifying the monomer raw material stage, but the selected perfluoropolyether long-chain groups still have higher toxicity and bioaccumulation problems compared to short-chain fluorine-containing groups. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a perfluorinated branched short-chain polysilazane and a preparation method thereof.

[0005] In the first aspect, the present invention provides a polysilazane containing a perfluorinated branched short chain, the structural formula of which is:

[0006]

[0007] Wherein, * refers to a repeating structural unit; x, y, z are integers between 5 and 200;

[0008] Q f It is a fluorinated group containing a short chain of perfluorinated branches, and its structural formula is as follows

[0009]

[0010] R 1 , R 2 , R 3 and R 4 is any of hydrogen, alkyl, vinyl, phenyl, allyl or trifluoropropyl; R 5 It is a hydrogen atom or a straight-chain or branched-chain alkyl group containing 1 to 4 carbon atoms.

[0011] R 6 It is a hydrogen atom or a straight-chain alkane containing 1 to 4 carbon atoms.

[0012] In a second aspect, the present invention provides a method for preparing the polysilazane containing perfluorinated branched short chains according to the first aspect, comprising:

[0013] (1) under the protection of an inert gas, adding chlorosilane and a perfluorinated branched short-chain compound into a solvent for reaction to obtain a fluorinated chlorosilane monomer;

[0014] (2) adding fluorine-containing chlorosilane monomer and chlorosilane monomer into a solvent, and carrying out an aminolysis reaction under the protection of an inert gas to prepare a polysilazane containing a perfluorinated branched short chain, i.e., a fluorine-containing polysilazane.

[0015] Further, in step (1), the structure of the chlorosilane contains at least one Si-Cl bond and one Si-H bond. Further, in step (1), the perfluorinated branched short-chain compound contains at least one active functional group, and the active functional group is -CH=CH 2 、-CH 2 CH=CH 2 , -COOH, -CH 2 At least one of OH; preferably, the active functional group is -CH=CH 2 .

[0016] Furthermore, the perfluorinated branched short chain compound has the following structural formula:

[0017]

[0018] Furthermore, in step (1), the catalyst for the reaction is a commonly used catalyst for hydrosilylation such as a platinum metal catalyst, a rhodium metal catalyst, a ruthenium metal catalyst or an iridium metal catalyst; preferably chloroplatinic acid, Karstedt, a phosphorus complex of zero-valent platinum, etc.

[0019] Furthermore, in step (1), the reaction temperature is 50 to 130° C., preferably 60 to 90° C., and the reaction time is 1 to 14 h, preferably 2 to 6 h.

[0020] Furthermore, in step (1) and step (2), the solvent is a mixed solvent of an organic solvent and a fluorinated solvent, wherein the organic solvent is at least one of toluene, xylene, ethylbenzene, n-hexane, n-octane, n-decane, cyclohexane, ethyl acetate, butyl acetate, tert-butyl acetate, ethyl ether, n-butyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, dichloromethane, chloroform, carbon tetrachloride, acetone, methyl butyl ketone and ethyl butyl ketone; and the fluorinated solvent is at least one of methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, para-fluorochlorobenzene, meta-fluorochlorobenzene, perfluorohexane, perfluorocyclohexane, perfluoromethylcyclohexane, perfluorotoluene, perfluoroheptane, perfluorodialkyl ether and perfluorotrialkylamine.

[0021] Furthermore, in step (2), the chlorosilane monomer is a commercially available chlorosilane; the chlorosilane is at least one of dichlorosilane, trichlorosilane, tetrachlorosilane, dimethyldichlorosilane, methylhydrogendichlorosilane, methylphenyldichlorosilane, methyltrichlorosilane, methylvinyldichlorosilane, trifluoropropylmethyldichlorosilane, hexachlorodisilane, diphenyldichlorosilane, phenyltrichlorosilane, ethyltrichlorosilane and ethyldichlorosilane.

[0022] Furthermore, the reactions are all carried out under the protection of inert gas.

[0023] Furthermore, in step (2), the ammonolysis reaction is carried out by introducing ammonia gas into the system.

[0024] Furthermore, in step (2), the temperature of the ammonolysis reaction is -50 to 50°C:

[0025] Furthermore, in step (2), the aminolysis reaction is terminated when the pH value of the aminolysis reaction system is ≥8.

[0026] In a third aspect, the present invention provides an antifouling coating prepared from the perfluorinated branched short-chain polysilazane described in the first aspect.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) The fluorine-containing polysilazane of the present invention has the advantages of polysilazane and the characteristics of fluorine-containing materials, and can be applied to special demand fields, such as low surface energy antifouling coating materials with ultra-high adhesion.

[0029] (2) The present invention modifies polysilazane by introducing perfluorinated branched short chains, thereby expanding the types of fluorinated polysilazanes. At the same time, the method effectively avoids the problems of high toxicity and bioaccumulation caused by long-chain perfluorinated groups. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the infrared spectrum of the fluorine-containing chlorosilane in Example 1.

[0031] Figure 2 This is the infrared spectrum of the fluorine-containing chlorosilane in Example 3. DETAILED DESCRIPTION

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0033] In the present invention, the ammonolysis reaction refers to reacting with fluorine-containing chlorosilane and chlorosilane by introducing ammonia into the system. The ammonolysis method is a well-known process, and its specific process is: a solvent, chlorosilane, and fluorine-containing chlorosilane are added to a reaction container at a certain temperature and under nitrogen protection, and then ammonia is introduced. After the reaction is completed, the ammonium chloride is removed, and then the reaction solvent is removed to obtain fluorine-containing polysilazane; or, an excess of liquid ammonia is added to the reaction container at a certain temperature and under nitrogen protection, and then chlorosilane and fluorine-containing chlorosilane are added. After the reaction is completed, the product and the by-product are separated, and the liquid ammonia is removed to obtain fluorine-containing polysilazane.

[0034] Example 1. Synthesis of fluorine-containing chlorosilane

[0035] Weigh 4 g of perfluoro branched short-chain methacrylate and 40 g of methylhydrogendichlorosilane (CH 3 SiHCl 2 ). Under an inert atmosphere, the two substances were added to a mixed solvent of xylene and p-fluorobenzyl chloride in a mass ratio of 10:1. Subsequently, 0.06wt% of Karstedt catalyst was added, and the reaction temperature was raised to 60°C and stirred for 8 hours under the protection of an inert atmosphere. After the reaction was completed, the solvent was removed to finally obtain a mixture of chlorosilane containing a perfluoro branched short-chain structure and methylhydrogendichlorosilane (fluorinated chlorosilane) with a total mass of 44g.

[0036] The structural formula of the fluorine-containing chlorosilane prepared in this embodiment is shown below, and its infrared spectrum is shown below Figure 1 shown.

[0037]

[0038] Example 2: Synthesis of fluorine-containing chlorosilane

[0039] Weigh 8g of perfluoro branched short-chain methacrylate and 40g of methylhydrogendichlorosilane (CH 3 SiHCl 2 ). Under an inert atmosphere, these two substances are added to a mixed solvent of xylene and p-fluorobenzyl chloride in sequence, with a mass ratio of 10:3. Subsequently, 0.2wt% of Karstedt catalyst is added, and the reaction temperature is raised to 80°C, and stirred for 8 hours under the protection of an inert atmosphere. After the reaction is completed, the solvent is removed to finally obtain a mixture of chlorosilane containing a perfluoro branched short-chain structure and methylhydrogendichlorosilane, with a total mass of 48g. The structural formula of the fluorine-containing chlorosilane prepared in this embodiment is the same as that in Example 1.

[0040] Example 3: Synthesis of fluorine-containing chlorosilane

[0041] Weigh 4g of perfluoro branched short-chain olefin and 40g of methylhydrogen dichlorosilane (CH3SiHCl2). Under an inert atmosphere, add these two substances to a mixed solvent of xylene and p-fluorobenzyl chloride in a mass ratio of 10:1. Subsequently, add 0.06wt% of Karstedt catalyst, raise the reaction temperature to 60°C, and stir for 8 hours under inert atmosphere protection. After the reaction is completed, remove the solvent to finally obtain a mixture of chlorosilane containing a perfluoro branched short-chain structure and methylhydrogen dichlorosilane, with a total mass of 44g.

[0042] The structural formula of the fluorine-containing chlorosilane prepared in this embodiment is shown below, and its infrared spectrum is shown below Figure 2 shown.

[0043]

[0044] Example 4: Synthesis of Fluorine-Containing Chlorosilane

[0045] Weigh 8g of perfluoro branched short-chain olefin and 40g of methylhydrogendichlorosilane (CH 3 SiHCl 2 ). Under an inert atmosphere, these two substances are added to a mixed solvent of xylene and p-fluorobenzyl chloride in sequence, with a mass ratio of 10:3. Subsequently, 0.2wt% of Karstedt catalyst is added, and the reaction temperature is raised to 80°C, and stirred for 8 hours under the protection of an inert atmosphere. After the reaction is completed, the solvent is removed to finally obtain a mixture of chlorosilane containing a perfluoro branched short-chain structure and methylhydrogendichlorosilane, with a total mass of 48g. The structural formula of the fluorine-containing chlorosilane prepared in this embodiment is the same as that in Example 3.

[0046] Example 5: Synthesis of Target Fluorinated Polysilazane

[0047] Under the protection of inert atmosphere, 180 ml of xylene, 20 ml of methyl nonafluorobutyl ether, 30 g of methylvinyldichlorosilane, 10 g of dimethyldichlorosilane, and 2 g of the fluorine-containing chlorosilane in Example 1 were added to a 500 ml three-necked flask, the temperature in the reaction system was controlled to be 0°C by low temperature circulation, ammonia was introduced into the reaction solution, and the reaction was stirred until the pH of the system was ≥ 9. Under the protection of inert atmosphere, the ammonium chloride produced by the reaction was removed, and the solvent was removed by rotary evaporation to obtain a perfluorinated branched short-chain structure polysilazane (fluorine-containing polysilazane) with a mass of 13 g.

[0048] The structure of the perfluorinated branched short-chain polysilazane prepared in this embodiment is shown below:

[0049]

[0050] The fluorinated polysilazane was used as raw material, propylene glycol methyl ether acetate was used as solvent, a solution with a mass concentration of 10% was prepared, dip-coated on a glass sheet, and cured at 200°C for 4 hours to obtain a smooth and transparent coating. The coating has good hydrophobic properties, with a water contact angle of 113°, which is better than the polysilazane whose fluorinated group is only trifluoropropyl. Benefiting from the characteristics of polysilazane, the hardness of the coating can reach 6H and the adhesion level reaches level 0.

[0051] Example 6: Synthesis of Target Fluorinated Polysilazane

[0052] Under the protection of inert atmosphere, 180 ml of xylene, 30 ml of methyl nonafluorobutyl ether, 30 g of methylvinyldichlorosilane, 10 g of dimethyldichlorosilane, and 4 g of the fluorine-containing chlorosilane in Example 3 were added to a 500 ml three-necked flask, the temperature in the reaction system was controlled to be 0°C by low temperature circulation, ammonia was introduced into the reaction solution, and the reaction was stirred until the pH of the system was ≥ 9. Under the protection of inert atmosphere, the ammonium chloride produced by the reaction was removed, and the solvent was removed by rotary evaporation to obtain a perfluorinated branched short-chain structure polysilazane with a mass of 14 g.

[0053] The structure of the perfluorinated branched short-chain polysilazane prepared in this embodiment is shown below:

[0054]

[0055] The fluorinated polysilazane was used as the raw material and propylene glycol methyl ether acetate was used as the solvent to prepare a solution with a mass concentration of 10%, which was dip-coated on a glass sheet and cured at 200°C for 4 hours to obtain a smooth and transparent coating. The coating has good hydrophobic properties and a water contact angle of 115°, which is better than the polysilazane whose fluorinated group is only trifluoropropyl. Benefiting from the characteristics of polysilazane, the hardness of the coating can reach 6H and the adhesion grade can reach level 0. Comparative Example, Synthesis of Trifluoropropyl-Containing Polysilazane

[0056] Under the protection of inert atmosphere, 180ml of xylene, 30ml of methyl nonafluorobutyl ether, 30g of methylvinyldichlorosilane (commercially available), 10g of dimethyldichlorosilane (commercially available), and 4g of trifluoropropylmethyldichlorosilane (commercially available) were added to a 500ml three-necked flask, and the temperature in the reaction system was controlled to be 0°C by low temperature circulation. Ammonia was introduced into the reaction solution, and the reaction was stirred until the pH of the system was ≥ 9. Under the protection of inert atmosphere, the ammonium chloride produced by the reaction was removed, and the solvent was removed by rotary evaporation to obtain a trifluoropropyl-containing polysilazane with a mass of 13g.

[0057] The structural formula of the trifluoropropyl-containing polysilazane prepared in this embodiment is as follows:

[0058]

[0059] Using the polysilazane as the raw material and propylene glycol methyl ether acetate as the solvent, a solution with a mass concentration of 10% was prepared, dip-coated on a glass sheet, and cured at 200°C for 4 hours to obtain a smooth and transparent coating. The coating has good hydrophobic properties and a water contact angle of 105°. Considering that the contact angle of water on a smooth perfluorinated surface is usually only 120°, it can be seen that Examples 5 and 6 have significant advantages in hydrophobic properties. This shows that these embodiments achieve higher contact angles through optimized design, improve the hydrophobicity of the surface, and have the potential to be used in scenarios requiring higher hydrophobic properties.

Claims

1. A polysilazane containing a perfluorinated short chain, characterized in that: Its structural formula is: Wherein, * refers to a repeating structural unit; x, y, z are integers between 5 and 200; Q f It is a fluorinated group containing a short chain of perfluorinated branches, and its structural formula is as follows R1, R2, R3 and R4 are any of hydrogen, alkyl, vinyl, phenyl, allyl or trifluoropropyl; R5 is a hydrogen atom or a straight or branched alkyl group containing 1 to 4 carbon atoms. R6 is a hydrogen atom or a straight-chain alkane containing 1 to 4 carbon atoms.

2. A method for preparing a polysilazane containing perfluorinated branched short chains as claimed in claim 1, characterized in that: include: (1) under the protection of an inert gas, adding chlorosilane and a perfluorinated branched short-chain compound into a solvent for reaction to obtain a fluorinated chlorosilane monomer; (2) adding fluorine-containing chlorosilane monomer and chlorosilane monomer into a solvent, and carrying out an aminolysis reaction under the protection of an inert gas to prepare a polysilazane containing a perfluorinated branched short chain, i.e., a fluorine-containing polysilazane.

3. The method according to claim 2, characterized in that In step (1), the structure of chlorosilane contains at least one Si-Cl bond and one Si-H bond.

4. The method according to claim 2, characterized in that In step (1), the perfluorinated branched short-chain compound contains at least one active functional group, wherein the active functional group is at least one of -CH=CH2, -CH2CH=CH2, -COOH, and -CH2OH; preferably, the active functional group is -CH=CH2; Furthermore, the perfluorinated branched short chain compound has the following structural formula:

5. The method according to claim 2, characterized in that In step (1), the catalyst for the reaction is one or more of a platinum metal catalyst, a rhodium metal catalyst, a ruthenium metal catalyst or an iridium metal catalyst; preferably one or more of chloroplatinic acid, Karstedt, and a phosphorus complex of zero-valent platinum.

6. The method according to claim 2, characterized in that In step (1), the reaction temperature is 50 to 130° C., preferably 60 to 90° C., and the reaction time is 1 to 14 h, preferably 2 to 6 h.

7. The method according to claim 2, characterized in that In step (1) and step (2), the solvent is a mixed solvent of an organic solvent and a fluorinated solvent, wherein the organic solvent is at least one of toluene, xylene, ethylbenzene, n-hexane, n-octane, n-decane, cyclohexane, ethyl acetate, butyl acetate, tert-butyl acetate, ethyl ether, n-butyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, dichloromethane, chloroform, carbon tetrachloride, acetone, methyl butanone and ethyl butanone; and the fluorinated solvent is at least one of methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, p-fluorochlorobenzene, m-fluorochlorobenzene, perfluorohexane, perfluorocyclohexane, perfluoromethylcyclohexane, perfluorotoluene, perfluoroheptane, perfluorodialkyl ether and perfluorotrialkylamine.

8. The method according to claim 2, characterized in that In step (2), the chlorosilane monomer is chlorosilane; the chlorosilane is at least one of dichlorosilane, trichlorosilane, tetrachlorosilane, dimethyldichlorosilane, methylhydrogendichlorosilane, methylphenyldichlorosilane, methyltrichlorosilane, methylvinyldichlorosilane, trifluoropropylmethyldichlorosilane, hexachlorodisilane, diphenyldichlorosilane, phenyltrichlorosilane, ethyltrichlorosilane and ethyldichlorosilane.

9. The method according to claim 2, characterized in that In step (2), the temperature of the ammonolysis reaction is -50 to 50°C.

10. An antifouling coating prepared from the perfluorinated branched short-chain polysilazane as claimed in claim 1.

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