Background
Surfaces with water and oil repellent properties are currently used in a wide variety of fields, such as self-cleaning coatings, sports and outdoor clothing, biomedical layers, integrated sensors, microfluidic channels, etc. These surfaces are typically achieved by a combination of substrate surface geometry and low surface energy chemical composition.
Since water has a high surface tension, lowering the surface free energy may achieve hydrophobicity or even superhydrophobicity of the surface. Since the surface tension of oil is 20 to 30mN/m, it is required that the surface free energy of the substrate is less than 20mN/m in order to achieve the oil-repellent effect. The low surface energy coating is a coating system which is rapidly developed in recent years, a low surface energy coating formed by the low surface energy coating can meet the requirements of water and oil repellency of the surface, and several types of low surface energy coatings, such as fluorine-containing acrylic polymer coatings, fluorine-containing siloxane polymer coatings, fluorine-containing polyurethane coatings and the like, are developed on the market at present.
Currently, long-chain perfluoroalkanes have been widely used for preparing low-surface-energy coatings to achieve water-and oil-repellency of surfaces, in which a long-chain fluoroalkyl group containing a POSS (oligomeric silsesquioxane) group can significantly enhance the hydrophobicity of materials, for example, blending a long-chain fluoroalkyl group having a POSS group with polymethyl methacrylate (PMMA) or polyethyl methacrylate (PEMA) can significantly enhance the hydrophobicity of a coating film, and further, for example, a POSS-terminated poly (3-caprolactone) epoxy resin to which POSS is added can significantly enhance the hydrophobicity. Therefore, the long-chain fluoroalkyl group-containing compound (polymer) containing POSS has excellent water-and oil-repellency, and can be used for preparing low-surface-energy coatings to realize water-and oil-repellency of the surface.
Although the long-chain fluoroalkyl group-containing compound has excellent water and oil repellency, the long-chain fluoroalkyl group-containing compound is difficult to degrade and has potential hazards to human health and the environment. For example, Perfluorooctanoate (PFOA), which has been fully detected in wild animals and plants as well as in humans and the environment, and studies have shown that PFOA, Perfluorooctylsulfonate (PFOS) and other perfluoroalkyl chain-containing molecules (CnF2n, n.gtoreq.8) can accumulate in wild animals and plants and in humans, with the potential for harm to human health and environmental pollution. Since 2000, the U.S. Environmental Protection Agency (EPA) has taken various measures to reduce the potential impact of long chain Perfluorochemicals (PFCs) on human health and the environment. Currently, the european union has banned the use of perfluorooctanesulfonic acid and is evaluating the risk of perfluorooctanoic acid exposure.
Fluoropolyethers are another fluorine-containing substance that has been shown to have no potential for irritation or skin sensitization, no detectable genotoxic activity in vitro or in vivo, and excellent physical and chemical properties, such as high chemical resistance, high lubricity, low surface energy, and low toxicity, and thus, fluoropolyethers are considered as the most promising alternatives to long-chain perfluoroalkanes. At present, there have been reports on the use of fluoropolyethers as water-and oil-repellent agents.
Although there are reports related to the application of POSS modified fluoropolyether substances in low surface energy coatings at present, the POSS modified fluoropolyether substances containing short fluorine chains (the length of the fluorocarbon chain is less than 6) have poor water and oil repellency and cannot well meet application requirements, so the POSS modified fluoropolyether substances which are reported at present and can be used for constructing water and oil repellent surfaces all contain long fluorine chains (the length of the fluorocarbon chain is more than or equal to 6), and the substances have excellent water and oil repellency, but are not easy to degrade and have potential risks of harming human health and polluting the environment.
Disclosure of Invention
In view of the above problems in the prior art, the present invention aims to provide a degradable fluorine-containing silicon fluoride copolymer with short fluorine chain, water and oil repellency, a preparation method thereof and an application thereof in low surface energy coating, so as to overcome the defects of the existing fluorine-containing silicon fluoride copolymer.
In order to achieve the purpose, the invention adopts the following technical scheme:
the water-repellent and oil-repellent fluorine-containing silicon copolymer is a polymer with a chemical structure general formula I or a general formula II:
wherein: r is selected from any one of C1-C18 alkyl (for example, methyl, ethyl, butyl, hexyl, octyl, lauryl, octadecyl, etc.), R1Is hydrogen or methyl, m is selected from any integer from 30 to 80, and n is selected from any integer from 10 to 30.
Preferably, the weight average molecular weight of the fluorine-containing silicon copolymer is 0.93X 104~2.64×104。
Preferably, the fluorine-containing silicon copolymer has the following chemical structural formula:
A method for producing the water-and oil-repellent fluorine-containing silicon copolymer of the present invention comprises mixing octavinyl silsesquioxane with a monomer represented by formula
And acrylic ester monomer represented by
The fluorine-containing unsaturated monomer is polymerized, and the reaction formula is shown as follows:
when the fluorine-containing silicon copolymer has the following chemical structural formula:
the water-and oil-repellent fluorine-containing silicon copolymer of (1) is prepared by: octavinyl silsesquioxane with methyl methacrylate monomer and
the fluorine-containing unsaturated monomer is polymerized, and the reaction formula is shown as follows:
as one embodiment, the fluorosilicone copolymer is prepared by first reacting an octavinyl silsesquioxane (i.e., octavinyl POSS, abbreviated as Ov-POSS) with a fluorinated polymer represented by formula
The acrylic ester monomer is polymerized and then reacts with the acrylic ester monomer shown as
The fluorine-containing unsaturated monomer (2) is polymerized.
As a preferred scheme, the compound is represented by
The acrylic ester monomer is selected from methyl methacrylate (R is methyl and R
1Is methyl), ethyl methacrylate (R is methyl, R
1Is ethyl), butyl methacrylate (R is methyl, R
1Butyl), hexyl methacrylate (R is methyl, R
1Hexyl), isooctyl methacrylate (R is methyl, R)
1Is isooctyl), lauryl methacrylate (R is methyl, R
1Lauryl), stearyl methacrylate (R is methyl, R
1Octadecyl), methyl acrylate (R is hydrogen, R
1Is methyl), ethyl acrylate (R is hydrogen, R
1Is ethyl), butyl acrylate (R is hydrogen, R
1Is butyl), hexyl acrylate (R is hydrogen, R
1Hexyl), isooctyl acrylate (R is hydrogen, R
1Is isooctyl), lauryl acrylate (R is hydrogen, R
1Lauryl), stearyl acrylate (R is hydrogen, R
1Octadecyl).
Preferably, the polymerization reaction is carried out in an organic solvent in the presence of an initiator, and the polymerization reaction temperature is 30-200 ℃.
Preferably, the polymerization reaction is carried out in an inert gas (e.g., nitrogen, argon, etc.) atmosphere.
Further preferably, the initiator is at least one selected from the group consisting of azo compounds (e.g., azobisisobutyronitrile, 1-t-amylazo-1-cyanocyclohexane, 1-t-butylazo-1-cyanocyclohexane), acyl peroxides (e.g., lauroyl peroxide), alkyl peroxides (e.g., di-t-butyl peroxide, t-butyl peroxybenzoate, t-butyl peroxyformate, t-butyl peroxyisooctanoate, t-butyl peroxy-2-ethylhexanoate), and hydroperoxides (e.g., diisopropylbenzene hydroperoxide, t-amyl hydroperoxide, t-butyl hydroperoxide).
In a further preferred embodiment, the organic solvent is at least one selected from the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons, ethers, esters, alcohols, ketones, dimethyl sulfoxide, and dimethylformamide.
As a further preferable mode, the organic solvent is at least one selected from the group consisting of n-hexane, n-heptane, cyclohexane, benzene, toluene, xylene, diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, butyl acetate, ethanol, isopropanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, dimethyl sulfoxide, dimethylformamide, trichloroethane, trifluorotoluene, perfluoro-n-butyl methyl ether, and tetrahydrofuran; among them, low water-soluble organic solvents are preferable, for example, ethyl acetate, butyl acetate, toluene, methyl ethyl ketone, and methyl isobutyl ketone.
As a further preferable scheme, the fluorine-containing silicon copolymer is prepared by firstly expressing the octavinyl silsesquioxane (namely, the octavinyl POSS, which is abbreviated as Ov-POSS) as
Carrying out polymerization reaction on the acrylate monomer and an initiator at the temperature of 30-200 ℃ to obtain a mixed solution containing a polymer intermediate; then adding the mixture containing the polymer intermediate as shown
And carrying out polymerization reaction on the fluorine-containing unsaturated monomer and the initiator at the temperature of 30-200 ℃ to obtain the fluorine-containing silicon copolymer.
As a further preferable scheme, when the octavinyl silsesquioxane and the acrylate monomer are polymerized, the molar weight of the added initiator is 0.1-5% of the molar weight of the acrylate monomer; when the polymer intermediate and the fluorine-containing unsaturated monomer are polymerized, the molar weight of the added initiator is 0.1-5% of the molar weight of the fluorine-containing unsaturated monomer.
As a further preferable scheme, after the reaction of the polymer intermediate and the fluorine-containing unsaturated monomer is finished, filtering is carried out, a filter cake is washed by a mixed solvent of methanol and chloroform, filtering and drying are carried out, and the fluorine-containing silicon copolymer is obtained.
As an embodiment, the
Is prepared from CF in the presence of alkali
3CF
2CF
2(CF
3)
2COH (i.e. perfluoro-2-methyl-2-pentanol) with
React to obtain
Is composed of
When the temperature of the water is higher than the set temperature,
is composed of
(i.e., methacryloyl halide)), X is a halogen, preferably Br or Cl, more preferably Cl.
Preferably, the base is an organic base selected from any one of triethylamine, pyridine, N-diisopropylethylamine, diethylamine, piperidine and N-methylpiperidine.
Preferably, the reaction temperature is-30 ℃ to room temperature (preferably-10 ℃ to 0 ℃), and the reaction solvent is ethylene glycol dimethyl ether, diethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, dichloromethane, DMF, benzene or 1, 2-dichloroethane.
Preferably, CF
3CF
2CF
2(CF
3)
2COH:
The molar ratio of the alkali is 1 (1-1.5) to 1-1.5.
As an embodiment, the
Is composed of CF
3CF
2CF
2(CF
3)
2COM (i.e. perfluoro-2-methyl-2-pentanolate) with
Reaction to obtain (A)
Is composed of
When the temperature of the water is higher than the set temperature,
(i.e., 4-vinylbenzyl halide)), M is an alkali metal (e.g., Li, Na, K), and X is a halogen (preferably Br, Cl, more preferably Cl).
Preferably, the reaction temperature is-30 ℃ to 100 ℃ (preferably-10 ℃ to room temperature), CF
3CF
2CF
2(CF
3)
2COM:
The molar ratio of (1-1.5) to (1).
Preferably, the reaction solvent is ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, dichloromethane, DMF, DMAc, benzene, 1, 2-dichloroethane, methanol or ethanol.
Preferably, said CF3CF2CF2(CF3)2COM made of CF3CF2CF2(CF3)2COH is obtained by reaction with a strong base expressed as MOH, which is a hydroxide of an alkali metal (e.g., KOH, NaOH, LiOH).
More preferably, the reaction solvent is ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, methylene chloride, DMF, DMAc, benzene, 1, 2-dichloroethane, methanol or ethanol.
More preferably, the reaction temperature is from-30 ℃ to 100 ℃ (preferably from-10 ℃ to room temperature).
As a further preferable embodiment, MOH: CF (compact flash)3CF2CF2(CF3)2The molar ratio of COH is (1~1.5):1。
The invention discloses an application of the water-repellent and oil-repellent fluorine-containing silicon copolymer as a coating main body for preparing a low-surface-energy coating.
Compared with the prior art, the invention has the following remarkable beneficial effects:
experiments prove that: the fluorine-containing silicon copolymer with the structure of the general formula I or the general formula II contains short fluorine chains, is degradable, has no potential harm to human health and environment, is safe and environment-friendly, has excellent water and oil repellency, can meet the performance requirement of preparing low-surface-energy paint, and can be used for constructing a water and oil repellent surface; in addition, the preparation method disclosed by the invention is simple to operate, the raw materials are easy to obtain, the cost is low, special equipment and a complex post-treatment process are not needed, the safety and the environmental protection are realized, the energy consumption is low, and the large-scale production is easy to realize; therefore, the invention has significant progress and outstanding advantages over the prior art.
Detailed Description
The technical scheme of the invention is further detailed and completely explained by combining the embodiment.
Example 1
Perfluoro-2-methyl-2-pentanol: CF (compact flash)3CF2CF2(CF3)2Preparation of COH:
5g (0.86mol) of dry potassium fluoride, 50ml of DMAC, 17.13g of perfluoro-2-methyl-2-pentene (0.0571mol) were charged into the reactor, stirred at below 7 ℃ for 1 hour and then passed under a weak stream of oxygen through 10.9g N2O4(0.118mol) and reacted for 48 hours to terminate the reaction, H was added3PO30.62g H3PO3Adding 40ml of water) to carry out quenching reaction, and distilling at normal pressure to obtain the perfluoro-2-methyl-2-pentanol CF3CF2CF2(CF3)2COH (colorless liquid, 65.7% yield).
Through the test:1H NMR(400MHz,DMSO-d6,δ):10.93(d,J=4.3Hz,1H);
19F NMR(376MHz,DMSO-d6,δ):-71.45–-71.86(m,6F),-80.09(d,J=11.7Hz,3F),-115.44(s,2F),-124.05(s,2F);
LRMS(EI),m/z(%):69.1(100),297.0(36.9)。
example 2
Potassium perfluoro-2-methyl-2-pentanol: CF (compact flash)3CF2CF2(CF3)2Preparation of COK:
dissolving 0.92g KOH (16mmol,1eq) in 12ml absolute ethyl alcohol, stirring for half an hour in an ice-water bath, dropwise adding 5.768g (17.17mmol,1.1eq) perfluoro-2-methyl-2-pentanol, reacting for 2 hours at room temperature, performing pressure distillation on the clear solution under vacuum (3mpa), and performing vacuum drying on the obtained residue under the temperature of 80 ℃ by using an oil pump to obtain the potassium perfluoro-2-methyl-2-pentanol: CF (compact flash)3CF2CF2(CF3)2COK contains potassium 2-methyl-2-pentanolate (white crystal, 5.984g, yield 100%).
Through the test:19F NMR(376MHz,DMSO-d6)δ:-73.82–-74.13(m,6F),-79.33(t,J=11.0Hz,3F),-115.03–-115.53(m,2F),-123.04–-123.75(m,2F);
LRMS(ESI)m/z:334.85(M-K);
HRMS(ESI)calcd.for C6F13O(M-K)334.9747,found.334.9740;
FT-IR(cm-1):1341.7,1204.8,1142.7,1114.0,955.8,817.0,751.9,734.2,715.0。
example 3
Fluorine-containing unsaturated monomer
The preparation of (1):
under the protection of nitrogen, 4g of perfluoro-2-methyl-2-pentanol (11.9mmol,1eq), 2.64ml (14.75mmol,1.24eq) of triethylamine and 20ml of diethyl ether are added into a reactor, stirred for 2 hours under a dry ice ethanol bath (the temperature is controlled to be about-10 ℃), then 1.49g (14.28mmol,1.2eq) of methacryloyl chloride is slowly dripped, the reaction is finished after the dripping, the reaction is carried out for 12 hours at room temperature, the reaction is finished, the reaction is quenched by 5 percent of dilute sulfuric acid under an ice water bath, an organic phase is washed by deionized water and saturated common salt solution, dried by anhydrous sodium sulfate, filtered, decompressed and distilled, and distilled at 8kPa, and 72 ℃ fractions are collected, thus obtaining the fluorine-containing unsaturated monomer
(colorless liquid, yield 98.17%).
Through the test:19F NMR(376MHz,CDCl3)δ:-66.08–-66.35(m),-80.49(t,J=12.4Hz),-112.57–-113.13(m),-124.11,-124.73(m);
1H NMR(400MHz,CDCl3)δ:6.22(d,J=0.7Hz,1H),5.82(t,J=3.4Hz,1H),1.98(dd,J=6.8,0.7Hz,3H);
13C NMR(101MHz,CDCl3)δ:159.97,133.87,130.06,17.99.IR(cm-1):1789.5,1247.0,1119.4,1078.7,995.9,736.2,720.0;
LRMS(EI),m/z(%):69.1(100),404.1(29.2);
HRMS(EI),m/z(100%):calcd for C10H5O2F13 404.0082,found 404.0077。
example 4
Fluorine-containing unsaturated monomer
The preparation of (1):
under the protection of nitrogen, 3.93g of perfluoro-2-methyl-2-pentanol potassium (10.5mmol,1.05equiv.) and 1.56g of 4-vinyl benzyl chloride (10mmol,1.0equiv.) are dissolved in 10mL of anhydrous DMAc, the reaction is stirred at room temperature for 24 hours, the reaction is finished, the reaction system is poured into diethyl ether, then the mixture is washed by deionized water and saturated common salt water in sequence, dried by anhydrous sodium sulfate, filtered, the solvent is dried in a spinning way, and column chromatography is carried out (EtOAc: PE is 1:40), thus obtaining the fluorine-containing unsaturated monomer
(colorless liquid, 4.16g, 92.1% yield).
Through the test:1H NMR(400MHz,CDCl3)δ:7.43(d,J=8.2Hz,2H),7.29(d,J=8.2Hz,2H),6.72(dd,J=17.6,10.9Hz,1H),5.78(d,J=17.6Hz,1H),5.29(d,J=10.9Hz,1H),5.02(s,2H);
19F NMR(376MHz,CDCl3)δ-65.73–-67.82(m,6F),-80.46(t,J=12.1Hz,3F),-112.04–-115.03(m,2F),-122.51–-126.03(m,2F);
13C NMR(101MHz,CDCl3)δ138.14,136.14,133.91,128.15,126.41,114.67,71.55;
LRMS(EI)m/z(%):117.1(100),452.1(92.2);
HRMS(EI)m/z(%):calcd for C15H9OF13 452.0447,found 452.0446;
IR(cm-1):1247.2,1166.8,1146.3,829.7,737.9,716.4。
example 5
Example 5.1
Fluorine-containing silicon copolymer
The preparation of (1):
under the protection of argon, dissolving octavinyl silsesquioxane and methyl methacrylate in THF, adding AIBN, and then stirring at 60 ℃ for reacting for 24 hours to obtain a mixed solution containing a polymer intermediate; then, adding fluorine-containing unsaturated monomer into the mixed solution containing the polymer intermediate under the protection of argon
And AIBN, stirring at 60 deg.C for 24 hr, terminating reaction, filtering, and adding CHCl to filter cake
3/CH
3Washing with OH (volume ratio 1/30) solution, drying to obtain white powder solid, namely, the copolymer containing fluorine and silicon
In this example, when methyl methacrylate was added, the molar ratio of methyl methacrylate to octavinyl silsesquioxane was 20:1, 13.3:1, and 10:1 in this order, and the molar amount of AIBN added was 0.1% of that of methyl methacrylate; when the fluorine-containing unsaturated monomer is added, the molar ratio of the fluorine-containing unsaturated monomer to the initially added octavinyl silsesquioxane is 10:1, 6.7:1 and 5:1 in sequence, and the added molar amount of AIBN is 0.1 percent of that of the fluorine-containing unsaturated monomer; the obtained fluorine-containing silicon copolymer is named as P1, P2 and P3 in sequence.
Example 5.2
Fluorine-containing silicon copolymer
The preparation of (1):
under the protection of argon, dissolving octavinyl silsesquioxane and methyl methacrylate in THF, adding AIBN, and then stirring at 60 ℃ for reacting for 24 hours to obtain a mixed solution containing a polymer intermediate; then, adding fluorine-containing unsaturated monomer into the mixed solution containing the polymer intermediate under the protection of argon
And AIBN, stirring at 60 deg.C for 24 hr, terminating reaction, filtering, and adding CHCl to filter cake
3/CH
3Washing with OH (volume ratio 1/30) solution, drying to obtain white powder solid, namely, the copolymer containing fluorine and silicon
In this example, when methyl methacrylate was added, the molar ratio of methyl methacrylate to octavinyl silsesquioxane was 40:1, 20:1, and 13.3:1 in this order, and the molar amount of AIBN added was 0.1% of methyl methacrylate; when the fluorine-containing unsaturated monomer is added, the molar ratio of the fluorine-containing unsaturated monomer to the initially added octavinyl silsesquioxane is 20:1, 10:1 and 6.7:1 in sequence, and the added molar amount of AIBN is 0.1 percent of that of the fluorine-containing unsaturated monomer; the obtained fluorine-containing silicon copolymer is named as P4, P5 and P6 in sequence.
The average yield of P1-P6 in this example was 71.8%.
The water and oil repellency of the obtained fluorine-containing silicon copolymer is tested by the following test method:
coating solutions with mass concentration of 6% are respectively prepared by the fluorine-containing silicon copolymer and THF, rinsed cotton fabrics (8cm multiplied by 8cm) are immersed in the coating solutions, placed for 1 hour, taken out and baked for 1 hour at 80 ℃, baked for 5 minutes at 160 ℃, cooled at room temperature, contact angles of the films with water and n-hexadecane are respectively tested, three times of each solution are tested, and an average value is obtained by averaging the three times. And (3) testing conditions are as follows: the liquid volume was 3 microliters, the height was 0.5 centimeters, and the magnification was 7 times, and the test results are shown in table 1.
TABLE 1 Performance test data for fluorosilicone copolymers
Sample (I)
|
m
|
n
|
Weight average molecular weight
|
Water contact Angle (°)
|
Contact Angle of n-hexadecane (°)
|
P1
|
68
|
26
|
17129
|
142
|
113
|
P2
|
57
|
21
|
14035
|
151
|
120
|
P3
|
47
|
18
|
11914
|
154
|
121
|
P4
|
30
|
21
|
12425
|
136
|
124
|
P5
|
32
|
20
|
12128
|
147
|
130
|
P6
|
35
|
19
|
11978
|
156
|
121 |
As can be seen from table 1: the contact angle of a coating film formed by the fluorine-containing silicon copolymer provided by the invention with water is as high as 156 degrees, and the contact angle of the coating film with n-hexadecane is as high as 130 degrees, which shows that the fluorine-containing silicon copolymer provided by the invention has excellent water and oil repellent performance, and the fluorine-containing silicon copolymer provided by the invention has short fluorine-containing chain, so that the fluorine-containing silicon copolymer is degradable, harmless to human bodies and environment, safe and environment-friendly, and can be used as a coating main body for preparing low surface energy coatings.
Finally, it should be pointed out here that: the above is only a part of the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention, and the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above description are intended to be covered by the present invention.