FLUORINE-CONTAINING GRAFT COPOLYMER, AND PREPARATION METHOD AND USE THEREOF

Abstract

The invention provides a fluorine-containing graft copolymer, and a preparation method and use thereof. The method includes the following steps: under a protective atmosphere, reacting a compound of Formula (I) and a compound of Formula (II) in a first organic solvent in the presence of a catalyst and a ligand at 20-30° C., to obtain the fluorine-containing graft copolymers of Formula (III) after complete reaction. The compounds of Formulas (I) and (II), and the fluorine-containing graft copolymer of Formula (III) have a structural formula shown below:

##STR00001##

##STR00002##

##STR00003##

and the compound of Formula (II) comprises a polyethylene glycol segment and a terminal alkynyl group, wherein a=4-8; b=6-8; n=1-20; and m=3-22. In the present invention, a graft copolymer of a main-chain-type “semi-fluorinated” alternating copolymer is obtained for the first time by post-polymerization modification using a reactive functional group contained in the main-chain-type “semi-fluorinated” alternating copolymers.

Claims

1. A method for preparing a fluorine-containing graft copolymer, comprising steps of: under a protective atmosphere, reacting a compound of Formula (I) and a compound of Formula (II) in a first organic solvent in the presence of a catalyst and a ligand at 20-30° C., to obtain the fluorine-containing graft copolymer of Formula (III), wherein the compounds of Formulas (I) and (II), and the fluorine-containing graft copolymers of Formula (III) have a structural formula shown below: ##STR00012## ##STR00013## ##STR00014## wherein a=4-8; b=6-8; n=1-20; and m=3-22.

2. The preparation method according to claim 1, wherein the compound of Formula (I) is prepared by a process comprising: under a protective atmosphere, reacting a compound of Formula (A) with an azide in a second organic solvent, in the presence of a phase catalyst at 50-55° C., to obtain the compound of Formula (I), wherein the compound of Formula (A) has a structural formula of: ##STR00015## wherein a=4-8; b=6-8; and n=1-20.

3. The preparation method according to claim 2, wherein the phase catalyst comprises a crown ether compound; and the second organic solvent is selected from the group consisting of chloroform, N, N-dimethyl formamide, dimethyl sulfoxide and any combination thereof.

4. The preparation method according to claim 2, wherein the molar ratio of the compound of Formula (A) to the azide is 1: 1-1:40; and the molar ratio of the compound of Formula (A) to the phase catalyst is 1: 2-1:80.

5. The preparation method according to claim 1, wherein the molar ratio of the compound of Formula (I) to the compound of Formula (II) is 1:20-1:80.

6. The preparation method according to claim 1, wherein the catalyst is selected from the group consisting of cuprous bromide, cuprous chloride, cupric sulfate pentahydrate and any combination thereof; and the ligand comprises pentamethyl diethylenetriamine and/or ascorbic acid.

7. The preparation method according to claim 1, wherein the molar ratio of the compound of Formula (I) to the catalyst is 1:1-1:4; and the molar ratio of the compound of Formula (I) to the ligand is 1:2-1:20.

8. The preparation method according to claim 1, wherein the first organic solvent is selected from the group consisting of toluene, N, N-dimethyl formamide, and tetrahydrofuran and any combination thereof.

9. A fluorine-containing graft copolymer prepared by the method according to claim 1, wherein the fluorine-containing graft copolymer comprises a lipophilic chain having a fluorine-containing segment and a hydrophilic chain having a polyethylene glycol segment, the polyethylene glycol segment is a side chain; and the fluorine-containing graft copolymer has a structural formula (III): ##STR00016## wherein a=4-8; b=6-8; n=1-20; and m=3-22.

10. Use of the fluorine-containing graft copolymer according to claim 9 in the preparation of a surfactant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0034] FIG. 1 shows the test results by .sup.1H NMR of a fluorine-containing alternating copolymer (AB).sub.n prepared in Example 1 of the present invention;

[0035] FIG. 2 shows the test results by .sup.19F NMR of the fluorine-containing alternating copolymer (AB).sub.n prepared in Example 1 of the present invention;

[0036] FIG. 3 shows the test results by .sup.1H NMR of a fluorine-containing alternating copolymer (AB).sub.n before and after nucleophilic substitution in Example 2 of the present invention;

[0037] FIG. 4 shows the test results by GPC of the fluorine-containing alternating copolymer (AB).sub.n before and after nucleophilic substitution in Example 2 of the present invention;

[0038] FIG. 5 shows the test results by FT- IR of the fluorine-containing alternating copolymer (AB).sub.n before and after nucleophilic substitution in Example 2 of the present invention;

[0039] FIG. 6 shows the test results by .sup.1H NMR of a nucleophilic substitution product before and after click reaction in Example 3 of the present invention;

[0040] FIG. 7 shows the test results by GPC of the nucleophilic substitution product before and after click reaction in Example 3 of the present invention;

[0041] FIG. 8 shows the test results by FT- IR of the nucleophilic substitution product before and after click reaction in Example 3 of the present invention;

[0042] FIG. 9 shows the test results by UV-vis spectroscopy of an aqueous solution of a fluorine-containing graft copolymer after heating;

[0043] FIG. 10 shows the test results of surface tension of the aqueous solution of the fluorine-containing graft copolymer at room temperature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] The specific embodiments of the present invention will be described in further detail by way of examples. The following examples are intended to illustrate the present invention, instead of limiting the scope of the present invention.

[0045] In the examples of the present invention, only the catalyst cuprous bromide and the ligand pentamethyl diethylene triamine need to be refined before use, and all other chemical reagents are commercially available and used directly.

[0046] In the examples of the present invention, the characterization conditions of the product are as follows:

[0047] .sup.1H NMR and .sup.19F NMR are performed on INOVA 600 MHz nuclear magnetic spectrometer, where the solvent is CDCl.sub.3, and the internal standard is TMS.

[0048] Preparation of test samples for .sup.1H NMR and .sup.19F NMR: About 15 mg of the sample is weighed, fed to an NMR tube, and added with 0.6 mL of CDCl.sub.3.

[0049] Molecular weight (M.sub.n) and polydispersity index (PDI): Waters 1515 Gel Permeation chromatograph (GPC), mobile phase tetrahydrofuran (THF), and column temperature: 30° C.

[0050] Preparation of test samples for GPC: About 10 mg of the sample is weighed, dissolved in 3-4 mL of THF, filtered through a syringe filter after thorough dissolution, and added to a sample vial.

[0051] The ultraviolet-visible (UV-vis) absorption spectra are measured on Shimadzu UV-2600 spectrophotometer, and the cloud point (CP) of the aqueous polymer solution is measured in a 1 cm quartz cell at 600 nm.

[0052] The surface/interfacial tension of the aqueous solution is tested at room temperature using the BZY-3B automatic meter/interfacial tensiometer.

[0053] Preparation of aqueous solution samples: The graft copolymer sample of various weight is weighed, dissolved in 5 mL of an aqueous solution, and stirred for 12 h to fully dissolve it, so as to prepare the sample to be tested.

Example 1: Synthesis of Fluorine-Containing Alternating Copolymer (AB).SUB.n

[0054] 1,6-Diiodoper-fluorohexane (C.sub.6F.sub.12I.sub.2), sodium ascorbate (AsAc-Na), tris(2,2′-bipyridine)ruthenium dichloride (Ru(bpy).sub.3Cl.sub.2), methanol (1 mL), 1,4-dioxane (3 mL), 1,7-octadiene (C.sub.8H.sub.14) were sequentially added to a 5 mL ampoule in proportion, wherein [C.sub.6F.sub.12I.sub.2].sub.0:[C.sub.8H.sub.14].sub.0:[Ru(bpy).sub.3Cl.sub.2].sub.0:[AsAc-Na].sub.0= 1.2:1:0.02:0.5 (molar ratio), with 0.5 mmol of 1,6-diiodoper-fluorohexane as a reference. After adding a stir bar, three rounds of freezing-evacuating-introducing argon were performed, and the ampoule was flame-sealed. The ampoule was irradiated under blue LED, and stirred at room temperature. At this time, the solution was bright red, reacted for a predetermined time and then removed, upon which the solution was dark brown. The solution was diluted with 1-2 mL of tetrahydrofuran, precipitated in a large amount of methanol in a disposable plastic cup, sealed with a plastic wrap, and then stood overnight in a freezer. The reaction solution was suction filtered under reduced pressure to obtain a purple-black product, which was dissolved in a small amount of tetrahydrofuran, passed through a neutral alumina column to remove metal salts, and precipitated in a large amount of methanol. The precipitate was white. It was allowed to stand overnight in a freezer, and then suction filtered under reduced pressure. The obtained white product was dried in a constant-temperature vacuum oven at 40° C. to a constant weight and weighed. Finally, a fluorine-containing alternating copolymer (AB).sub.n was obtained with a yield of 75%. The structure of the fluorine-containing alternating copolymer (AB).sub.n is shown below:

##STR00009##

where n = 5-10.

[0055] The molecular weight (M.sub.n) and polydispersity index (PDI) of the polymer were measured by gel permeation chromatography (GPC), and the structure was characterized by .sup.1H NMR and .sup.19F NMR. The results are shown in FIGS. 1-2. In FIG. 1, the peaks at different chemical shifts on the NMR spectrum can be attributed to corresponding moieties in the structural formula of the polymer. The peak at 7.26 ppm is the shift peak of deuterated chloroform (CDCl.sub.3). In FIG. 2, the peaks at different chemical shifts on the NMR spectrum can be attributed to corresponding moieties in the structural formula. The above results show that the expected fluorine-containing alternating copolymer (AB).sub.n is obtained through the above-mentioned steps.

Example 2: Nucleophilic Substitution of Fluorine-Containing Alternating Copolymer (AB).SUB.n

[0056] Sodium azide was used as the nucleophilic reagent, the phase catalyst was 18-crown-6, and the nucleophilic reaction gave a fluorine-containing alternating copolymer (AB).sub.n-N.sub.3. The reaction route and specific steps were as follows.

##STR00010##

[0057] The fluorine-containing alternating copolymer (AB).sub.n (1.0 eq.) prepared in Example 1, sodium azide (20.0 eq.), 18-crown-6 (40.0 eq.), and chloroform (2.0 mL) were sequentially added to a 5 mL ampoule in proportion. After adding a stir bar, three rounds of freezing-evacuating-introducing argon were performed, and the ampoule was flame-sealed. The ampoule was placed in a heated stirrer at 55° C., stirred, and removed after a predetermined period of time. The ampoule was opened and the solution was diluted with 1 to 2 mL of tetrahydrofuran, which was passed through a neutral alumina column to remove unreacted NaN.sub.3 and precipitated in a large amount of methanol. Then, it was sealed with a plastic wrap, and stood overnight in a freezer. The reaction solution was suction filtered under reduced pressure to obtain a yellowish product. The obtained yellowish product was dried in a low-temperature vacuum temperature to a constant weight and weighed. Finally, the fluorine-containing alternating copolymer (AB).sub.n-N.sub.3 was obtained after nucleophilic substitution.

[0058] The .sup.1H NMR spectra of the polymer before and after nucleophilic substitution are shown in FIG. 3. After C—I is nucleophilic substituted and becomes —N.sub.3, the shift peak (4.2-4.4 ppm) originally attributed to —CH.sub.2CH(I)CH.sub.2— and the shift peak (2.6-3.1 ppm) attributed to —CF.sub.2CH.sub.2CH(I)— are both shifted toward the high field, and the peaks at other chemical shifts can be attributed to corresponding moieties in the structural formula of the polymer.

[0059] The GPC chromatogram of the copolymer before and after nucleophilic substitution are shown in FIG. 4. As shown by the GPC chromatogram of (AB).sub.n before and after nucleophilic substitution in FIG. 4, it can be seen that the molecular weight of (AB).sub.n is 5600 g/mol, and M.sub.w/M.sub.n = 1.43; and the molecular weight of the product after substitution is 8400 g/mol, and M.sub.w/M.sub.n=1.25.

[0060] The FT- IR spectra of the polymer before and after nucleophilic substitution are shown in FIG. 5. After nucleophilic substitution, the infrared absorption of —N.sub.3 at 2110 cm.sup.-1 is clearly shown in the spectra, confirming the successful synthesis of nucleophilic substituted product.

Example 3. Synthesis of Graft Copolymer of Main Chain Type “Semi-Fluorinated” Alternating Copolymer

[0061] The fluorine-containing alternating copolymer (AB).sub.n—N.sub.3 (1.0 eq.) obtained after nucleophilic substitution prepared in Example 2, OMEG having a polyethylene glycol segment and a terminal alkynyl group (20.0 eq.), cuprous bromide (2.0 eq.), pentamethyldiethylenetriamine (PMDETA) (2.0 eq.), and tetrahydrofuran (2.0 mL) were sequentially added to a 5 mL ampoule in proportion. After adding a stir bar, three rounds of freezing-evacuating-introducing argon were performed, and the ampoule was flame-sealed. The ampoule was placed in a heated stirrer at 25° C., stirred, and removed after a predetermined period of time. The ampoule was opened, and the solution was diluted with 1 to 2 mL of tetrahydrofuran, passed through a neutral alumina column to remove the metal salt catalyst, precipitated in a large amount of petroleum ether, sealed with a plastic wrap and then allowed to settle down overnight at room temperature. On the following day, the supernatant was decanted, and the polymer was dried in a constant-temperature vacuum oven at 40° C. to a constant weight and weighed. Finally, the graft copolymer (AB).sub.n-g-OMEGwith main chain type “semi-fluorinated” alternating copolymer backbone was obtained.

[0062] The .sup.1H NMR spectra of the graft copolymers before and after reaction are shown in FIG. 6. After the reaction, the appearance of the chemical shift of 7.59 ppm indicates the successful addition of the azido group to the alkynyl group, and the chemical shits of 4.69 ppm, 3.67 ppm and 3.36 ppm also correspond to the structures on the OMEG chain. These experimental results all successfully demonstrate the successful synthesis of the graft copolymers.

[0063] The GPC traces of the graft copolymers (AB).sub.n-g-OMEG before and after reaction are shown in FIG. 7. After the “click” reaction, the molecular weight of the polymer is increased, and the GPC traces shows the single peak and shifted toward higher molecular weight. The specific results are shown in Table 1.

TABLE-US-00001 “Click” reaction of fluorine-containing alternating copolymer (AB).sub.n-N.sub.3 with OMEG of different chain lengths Entry M .sup.a[(AB).sub.n-N.sub.3I.sub.0:[OMEG].sub.0:[CuBr].sub.0:[PMDETA].sub.0 T (°C) .sup.bM.sub.n,GPC (g/mol) .sup.bM.sub.w/M.sub.n 1 OMEG.sub.3 1:20:2:2 25 9700 1.25 2 OMEG.sub.6 1:20:2:2 25 12600 1.29 3 OMEG.sub.9 1:20:2:2 25 13300 1.22 4 OMEG.sub.22 1:20:2:2 50 21000 1.14

[0064] Reaction conditions: m.sub.(AB)n-N3= 0.1 g, M.sub.(AB).sub.n-N3 = 8400 g/mol, M.sub.w/M.sub.n = 1.25. V.sub.THF = 2 mL, t = 24 h. .sup.aRiato = [(AB).sub.n-N.sub.3].sub.0:[OMEG].sub.0:[CuBr].sub.0:[PMDETA].sub.0. .sup.b Molecular weight and molecular weight distribution measured by GPC (using linear PMMA in THF as standard).

[0065] In this embodiment, the structural formula OMEG is shown below:

##STR00011##

. As shown in Table 1, OMEG.sub.3, OMEG.sub.6, OMEG.sub.9, and OMEG.sub.22 have an m of 3, 6, 9, and 22 respectively. In FIGS. 6-10, (AB).sub.n-g-OMEG.sub.3, (AB).sub.n-g-OMEG.sub.6, (AB).sub.n-g-OMEG.sub.9 and (AB).sub.n-g-OMEG.sub.22 are respectively corresponding products prepared with OMEG.sub.3, OMEG.sub.6, OMEG.sub.9, and OMEG.sub.22.

[0066] The FT-IR spectra of the graft copolymers (AB).sub.n-g-OMEG before and after reaction are shown in FIG. 8. After the reaction, the previous infrared absorption of —N.sub.3 (at 2110 cm.sup.-1) disappears completely, confirming the success of the “Click” reaction.

Example 4. Use of Graft Copolymer of Main Chain Type “Semi-Fluorinated” Alternating Copolymer in the Preparation of Surfactants

[0067] The UV-vis absorption spectra of the aqueous solutions of (AB).sub.n-g-OMEG.sub.6, (AB).sub.n-g-OMEG.sub.9, and (AB).sub.n-g-OMEG.sub.22 prepared in Example 3 are shown in FIG. 9. The sample concentration of each aqueous solution is 2.0 mg/mL. The corresponding cloud points of (AB).sub.n-g-OMEG.sub.6 and (AB).sub.n-g-OMEG.sub.9 are respectively 36.2° C. and 67.7° C. It can be seen that with the growth of the side chain, the cloud point (CP) also increases accordingly, until no cloudy phenomenon is observed within the test limits.

[0068] The surface tension test results of the aqueous solution of the graft copolymer prepared in Example 3 are shown in FIG. 10. The surface tension of the aqueous solution decreases with the increase of the concentration of each sample, and approaches a limit. In addition, compared with (AB).sub.n-g-OMEG.sub.9 and (AB).sub.n-g-OMEG.sub.22, (AB).sub.n-g-OMEG.sub.6 has better performance as a surfactant, which also correlates with the length of the side chain. Samples with a shorter side chain has a more potent ability to reduce the surface tension of the aqueous solution at the same test concentration.

[0069] While preferred embodiments of the present invention have been described above, the present invention is not limited thereto. It should be noted that some improvements and variations can be made by those skilled in the art without departing from the technical principles of the present invention, which are also contemplated in the protection scope of the present invention.