PHOTOPOLYMERIZATION METHOD FOR PREPARING BLOCK COPOLYMER WITH MAIN-CHAIN SEMI-FLUORINATED ALTERNATING COPOLYMER

Abstract

The present invention relates to a photopolymerization method for preparing a block polymer with a main-chain “semi-fluorinated” alternating copolymer, which comprises the following steps: under a protective atmosphere, subjecting a methacrylate monomer and a “semi-fluorinated” alternating copolymer (AB).sub.n macroinitiator to light-controlled living radical polymerization in an organic solvent at 20-30° C. in the presence of a photocatalyst, where the polymerization reaction is continued for at least half an hour under irradiation of light at 390-590 nm, to obtain a block copolymer of a main-chain polyolefin, polyester, or polyether “semi-fluorinated” alternating copolymer. The polymerization method is carried out under irradiation of visible light, the polymerization process has the characteristics of “living” radical polymerization, and the molecular weight distribution of the prepared polymer is narrow.

Claims

1. A photopolymerization method for preparing a block copolymer with a main-chain “semi-fluorinated” alternating copolymer, comprising steps of: under a protective atmosphere, subjecting a methacrylate monomer and a “semi-fluorinated” alternating copolymer (AB).sub.n macroinitiator to light-controlled living radical polymerization in an organic solvent at 20-30° C. in the presence of a photocatalyst, where the polymerization is continued for at least half an hour under irradiation of light at 390-590 nm, to obtain a block copolymer of the main-chain “semi-fluorinated” alternating copolymer, wherein when the “semi-fluorinated” alternating copolymer(AB).sub.n macroinitiator has a structure of Formula (1), the resulting block copolymer of the main-chain “semi-fluorinated” alternating copolymer has a structure of Formula (2); and when the “semi-fluorinated” alternating copolymer(AB).sub.n macroinitiator has a structure of Formula (3), the resulting block copolymer of the main-chain “semi-fluorinated” alternating copolymer has a structure of Formula (4), in which Formulas (1)-(4) are shown below: ##STR00005## where x=4-8, y=0-3, n=4-30, and m=100-500; R is selected from a C.sub.1-C.sub.6 alkyl group, an aryl ether group or an acyloxy group; and R.sub.1 is selected from a C.sub.1-C.sub.6 alkyl group, a polyethylene glycol group, a C.sub.1-C.sub.6 alkyl group substituted with amino, or a C.sub.1-C.sub.6 alkyl group substituted with epoxy.

2. The photopolymerization method according to claim 1, wherein the methacrylate monomer is methyl methacrylate, butyl methacrylate, hexyl methacrylate, glycidyl methacrylate, N,N-dimethylaminoethyl methacrylate, or polyethylene glycol monomethyl ether methacrylate.

3. The photopolymerization method according to claim 1, wherein the “semi-fluorinated” alternating copolymer(AB).sub.n macroinitiator is obtained by START polymerization of a monomer A with a monomer B, wherein the monomer A is selected from 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane or 1,8-diiodoperfluorooctane; and the monomer B is selected from 1,7-octadiene, 1,9-decadiene, 1,4-phenylene diallyl ether, 1,4-phenylene bis(1-hexenyl) ether, diallyladipate, diallyl terephthalate or bis(1-hexenyl) terephthalate.

4. The photopolymerization method according to claim 1, wherein the molar ratio of the monomer A to the monomer B is 1-1.2:1.

5. The photopolymerization method according to claim 1, wherein x=4, 6, or 8.

6. The photopolymerization method according to claim 1, wherein y=0 or 1.

7. The photopolymerization method according to claim 1, wherein the photocatalyst is tris(2,2′-bipyridine)ruthenium dichloride and sodium ascorbate.

8. The photopolymerization method according to claim 1, wherein the concentration of the methacrylate monomer in the organic solvent is 0.002 mol/mL-0.1 mol/mL.

9. The photopolymerization method according to claim 1, wherein the molar ratio of the methacrylate monomer to the “semi-fluorinated” alternating copolymer(AB).sub.n macroinitiator is 30-500:1-3.

10. A block copolymer with a main-chain “semi-fluorinated” alternating copolymer of Formula (2) or Formula (4) prepared by the photopolymerization method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 is a .sup.1H NMR spectrum of the main-chain “semi-fluorinated” alternating copolymer (AB.sub.1).sub.n;

[0038] FIG. 2 is a .sup.19F NMR spectrum of the main-chain “semi-fluorinated” alternating copolymer (AB.sub.1).sub.n;

[0039] FIG. 3 is a .sup.1H NMR spectrum of the block copolymer (AB.sub.1).sub.n-b-PMMA of the main-chain “semi-fluorinated” alternating copolymer prepared in Example 1;

[0040] FIG. 4 shows a curve of elution by GPC of the block copolymer (AB.sub.1).sub.n-b-PMMA of the main-chain “semi-fluorinated” alternating copolymer obtained at various polymerization times in Example 1;

[0041] FIG. 5 shows a first-order kinetic curve of the monomer concentration [M] of the block monomer (AB.sub.1).sub.n-b-PMMA of the “semi-fluorinated” alternating copolymer vs reaction time in Example 1;

[0042] FIG. 6 shows a curve of relation between M.sub.n, M.sub.w/M.sub.n and the conversion rate of the block copolymer (AB.sub.1).sub.n-b-PMMA of the “semi-fluorinated” alternating copolymer;

[0043] FIG. 7 is a .sup.1H NMR spectrum of the main-chain “semi-fluorinated” alternating copolymer (AB.sub.1).sub.nA in Example 3;

[0044] FIG. 8 is a .sup.1H NMR spectrum of the main-chain “semi-fluorinated” alternating copolymer (AB.sub.2).sub.n in Example 3;

[0045] FIG. 9 is a .sup.1H NMR spectrum of the main-chain “semi-fluorinated” alternating copolymer (AB.sub.3).sub.n in Example 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] The present invention will be further described below by way of examples with reference to the accompanying drawings. The descriptions below are only preferred examples of the present invention, and are not intended to limit the present invention. For those skilled in the art, various modifications and changes can be made to the present invention without departing from the spirit and principle of the present invention, which are all fall within the protection scope of the present invention.

[0047] Chemical reagents used in examples of the present invention: methyl methacrylate (95%), purchased from Aladdin; glycidyl methacrylate (>95%), purchased from TCI; 2-(dimethylamino)ethyl methacrylate (>98.5%), purchased from TCI; polyethylene glycol) methyl ether methacrylate (PEGMA, M.sub.n=300 g mol.sup.−1), purchased from Aldrich; tris (2,2′-bipyridine)ruthenium dichloride (98%), purchased from Energy Chemical Co., Ltd.; sodium ascorbate, purchased from Bellingway Technology Co., Ltd. acetone, AR; tetrahydrofuran, AR; and methanol, industrial grade.

[0048] Test equipment: PL gel permeation chromatograph; INOVA 400 MHz Nuclear Magnetic Resonance Spectrometer.

[0049] Test conditions: HR1, HR3 and HR4 used in tandem, differential detector, mobile phase tetrahydrofuran (1 mL/min), column temperature 30° C., and correction with a standard prepared with polystyrene or polymethyl methacrylate. .sup.1H NMR spectrum was obtained on INOVA 300 MHz Nuclear Magnetic Resonance Spectrometer with TMS as internal standard.

Example 1

[0050] The monomer methyl methacrylate (5 mmol) to be polymerized, the alternating fluoropolymer macroinitiator (AB.sub.1).sub.n (0.01 mmol), the photocatalyst tris (2,2′-bipyridine)ruthenium dichloride (Ru(bpy).sub.3Cl.sub.2) (0.002 mmol), sodium ascorbate (AsAc—Na) (0.01 mmol), and acetone (0.5 mL) were added to a photoreaction tube, deoxygenated, and polymerized at room temperature under blue LED irradiation at 485 nm. After a predetermined time of reaction, the reaction tube was opened, a small amount of polymer solution was taken for test by .sub.1H NMR spectroscopy, and the conversion rate of the monomer and the molecular weight (M.sub.n,NMR) by .sub.1H NMR spectroscopy were calculated. The rest of the polymer solution was dissolved in a certain amount of tetrahydrofuran. After passing through a neutral Al.sub.2O.sub.3 column, a precipitating agent was added, and after standing, suction filtering, and drying under vacuum, a block copolymer (AB.sub.1).sub.n-b-PMMA of a “semi-fluorinated” alternating copolymer was obtained. FIGS. 1-2 show the test results by .sup.1H NMR and .sup.19F NMR spectroscopy of (AB.sub.1).sub.n respectively. The degree of polymerization is 8-9. FIG. 3 is a .sup.1H NMR spectrum of the block copolymer (AB.sub.1).sub.n-b-PMMA of the “semi-fluorinated” alternating copolymer.

[0051] Multiple sets of parallel experiments were performed following the above steps. The polymerization time was 1, 2, 4, 6, 8 and 10 h respectively. The polymerization results of (AB.sub.1).sub.n-b-PMMA at various times were tested.

[0052] FIG. 4 shows a curve of elution by GPC of (AB.sub.1).sub.n-b-PMMA obtained at various polymerization times. From right to left, the reaction time corresponding to the curve is gradually extended, and the polymerization time is 1, 2, 4, 6, 8, and 10 h, respectively. The molecular weights and polydispersity indices (PDIs) of (AB.sub.1).sub.n-b-PMMA obtained are 21400 g/mol, 1.70; 27800 g/mol, 1.44; 32000 g/mol, 1.37; 37600 g/mol, 1.38; 38100 g/mol, 1.34; 46200 g/mol, 1.55 respectively.

[0053] FIGS. 5-6 shows the first-order kinetic curve of the monomer concentration [M] of (AB.sub.1).sub.n-b-PMMA vs reaction time, and the curve of relation between M.sub.n and M.sub.w/M.sub.n and the conversion rate of (AB.sub.1).sub.n-b-PMMA. The results show that the change curves of molecular weight and molecular weight distribution of the polymer indicate that the molecular weight M.sub.n,GPC increases linearly with the conversion rate of the monomer, the polymer has good controllability, and the molecular weight distribution is narrow.

Example 2

[0054] Various monomers (5 mmol) to be polymerized, the alternating fluoropolymer macroinitiator (AB.sub.1).sub.n (0.025 mmol), the photocatalyst tris(2,2′-bipyridine)ruthenium dichloride (Ru(bpy).sub.3Cl.sub.2) (0.005 mmol), sodium ascorbate (AsAc—Na) (0.025 mmol), and acetone (0.5 mL) were added to a photoreaction tube, deoxygenated, and polymerized at room temperature under blue LED irradiation at 485 nm. The molecular weight of (AB.sub.1).sub.n is 4000 g/mol, and PDI is 1.40. After a predetermined time of reaction, the reaction tube was opened, a small amount of polymer solution was taken for test by .sup.1H NMR spectroscopy, and the conversion rate of the monomer and the molecular weight (M.sub.n,NMR) by .sup.1H NMR spectroscopy were calculated. The rest of the polymer solution was dissolved in a certain amount of tetrahydrofuran. After passing through a neutral Al.sub.2O.sub.3 column, a precipitating agent was added, and after standing, suction filtering, and drying under vacuum, a polymer was obtained. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 Polymerization results of various polymerization systems Time Conversion M.sub.n, th M.sub.n, GPC No. Monomer (h) rate (%) (g/mol) (g/mol) M.sub.w/M.sub.n 1 GMA 24 79.9 26700 34400 1.28 2 DMAEMA 24 99.5 34000 39600 1.21 3 PEGMA-300 12 37.2 28000 46600 1.55  4.sup.a PEGMA-300 12 87.2 31900 46900 1.60

[0055] In Table 1, the test conditions of No. 4 is [M].sub.0:[(AB.sub.1).sub.n].sub.0:[Ru(bpy).sub.3Cl.sub.2].sub.0:[AsAc—Na].sub.0=100:1:0.2:1. In Table 1, PEGMA-300 and PEGMA-400 respectively means that the molecular weight of polyethylene glycol in the polyethylene glycol monomethyl ether methacrylate is 300 g/mol or 400 g/mol.

Example 3

[0056] The monomer methyl methacrylate (5 mmol) to be polymerized, various alternating fluoropolymer macroinitiator (AB.sub.1).sub.nA, (AB.sub.2).sub.n or (AB.sub.3).sub.n (0.01 mmol), the photocatalyst tris(2,2′-bipyridine)ruthenium dichloride (Ru(bpy).sub.3Cl.sub.2) (0.002 mmol), sodium ascorbate (AsAc—Na) (0.01 mmol), and acetone (0.5 mL) were added to a photoreaction tube, deoxygenated, and polymerized at room temperature under blue LED irradiation at 485 nm. The molecular weight and PDI of (AB.sub.1).sub.nA, (AB.sub.2).sub.n or (AB.sub.3).sub.n are respectively 6400 g/mol, 1.75; 2200 g/mol, 1.28; and 9800 g/mol, 1.91.

[0057] After a predetermined time of reaction, the reaction tube was opened, a small amount of polymer solution was taken for test by .sup.1H NMR spectroscopy, and the conversion rate of the monomer and the molecular weight (M.sub.n,NMR) by .sup.1H NMR spectroscopy were calculated. The rest of the polymer solution was dissolved in a certain amount of tetrahydrofuran. After passing through a neutral Al.sub.2O.sub.3 column, a precipitating agent was added, and after standing, suction filtering, and drying under vacuum, a polymer was obtained.

[0058] FIGS. 7-9 respectively show the test results by .sup.1H NMR of the macroinitiator (AB.sub.1).sub.nA, (AB.sub.2).sub.n or (AB.sub.3).sub.n in this example.

[0059] Table 2 shows the results of polymerization using different macroinitiators. It can be seen that the polymerization of methyl methacrylate monomer is successfully achieved, and the molecular weight distribution of the resulting polymer is narrow.

TABLE-US-00002 TABLE 2 Effects of different macroinitiators on the polymerization system Time Conversion M.sub.n, th M.sub.n, GPC No. Monomer (h) rate (%) (g/mol) (g/mol) M.sub.w/M.sub.n 1 (AB.sub.1).sub.nA 5.5 32.5 22700 32300 1.34 2 (AB.sub.2).sub.n 11 33.3 18900 50900 1.43 3 (AB.sub.3).sub.n 10 45.2 32400 25200 1.99

[0060] In Table 2, [MMA].sub.0:[(AB).sub.n].sub.0:[Ru(bpy).sub.3Cl.sub.2].sub.0:[AsAc—Na].sub.0=500:1:0.2:1.

[0061] The above description is only preferred embodiments of the present invention and not intended to limit the present invention, it should be noted that those of ordinary skill in the art can further make various modifications and variations without departing from the technical principles of the present invention, and these modifications and variations also should be considered to be within the scope of protection of the present invention.