CN101280069A - A kind of preparation method and application of crosslinking agent for synthesizing amphiphilic gel - Google Patents

Abstract

The invention belongs to the technical field of organogels, in particular to a preparation method and application of a cross-linking agent for synthesizing amphiphilic gels. The cross-linking agent is a bifunctional cross-linking agent containing tert-butyl acrylate groups and alkoxyamine groups. It first undergoes atom transfer freedom with tert-butyl acrylate or a class of monomers containing tert-butyl acrylate groups. tert-butyl polyacrylate gel, and the alkoxyamine group in the poly-tert-butyl acrylate gel triggers the polymerization of styrene or a class of monomers containing styrene groups, thereby obtaining tert-butyl polyacrylate Ester-polystyrene two-block gel, which is swelled in dichloromethane and then added with trifluoroacetic acid, in which the polyacrylic acid tert-butyl ester segment is hydrolyzed into polyacrylic acid, thus obtaining amphiphilic polyacrylic acid-polyacrylic acid Styrene diblock gels. When the cross-linking agent is used to synthesize the amphiphilic gel, the reaction yield is high, the reaction condition requirement is relatively mild, and the product has the characteristics of lipophilic and hydrophilic amphiphilic.

Description

A kind of preparation method and application of crosslinking agent for synthesizing amphiphilic gel

Technical field:

The invention belongs to the technical field of organogels, in particular to a preparation method and application of a cross-linking agent for synthesizing amphiphilic gels.

Background technique:

At present, the main method for synthesizing amphiphilic gels is to firstly synthesize lipophilic and hydrophilic polymer monomers respectively, and then cross-link the two monomers to form amphiphilic gels. The disadvantage of this synthesis method is that in the process of synthesizing the amphiphilic gel, the reaction rate is low in the key step of cross-linking two polymers with different properties, and the reaction efficiency is also low in the synthesis process of two different phases of monomers. lower.

Invention content:

The object of the present invention is to propose a cross-linking agent for synthesizing amphiphilic gel, so that the synthetic amphiphilic gel has high reaction yield, mild reaction conditions, and the product has the characteristics of lipophilic and hydrophilic amphiphilic.

The cross-linking agent for the synthesis of amphiphilic gel proposed by the present invention is a bifunctional cross-linking agent containing tert-butyl acrylate group and alkoxyamine group, and its structural formula is as follows:

The preparation method of the cross-linking agent for the synthesis of amphiphilic gel proposed by the present invention, the specific steps are: utilize the method of atom transfer radical addition, at first by 4-hydroxyl-2,2,6,6, tetra Methylpiperidine and triethylamine prepare tert-butyl acrylate derivatives containing nitroxide free radicals at a low temperature of -10 to 5°C, and then combine tert-butyl acrylate derivatives containing nitrogen oxide free radicals with binary halogen The benzene derivatives of the substitutes are subjected to atom transfer radical addition reaction at 15-40°C to obtain the required cross-linking agent.

The cross-linking agent proposed by the present invention can be used to synthesize amphiphilic gel, and the specific steps are: the cross-linking agent first undergoes atom transfer radical polymerization copolymerization with tert-butyl acrylate or a class of monomers containing tert-butyl acrylate groups A poly(tert-butyl acrylate) gel is formed, and the alkoxyamine group in the poly(tert-butyl acrylate) gel triggers the nitrogen-oxygen-regulated free radical polymerization of styrene or a type of monomer containing a styrene group, thereby obtaining a poly(tert-butyl acrylate) gel. tert-butyl acrylate-polystyrene diblock gel, which is swelled in dichloromethane and then added with trifluoroacetic acid, in which the poly-tert-butyl acrylate segment is hydrolyzed into polyacrylic acid, thereby obtaining amphiphilic polystyrene Acrylic polystyrene diblock gel.

The cross-linking agent proposed by the present invention can first synthesize a two-block lipophilic gel, and then hydrolyze a component in the gel to form an amphiphilic gel, which improves the yield of the reaction and ensures the amphiphilicity properties of the gel.

The cross-linking agent proposed by the present invention can realize the cross-linking degree required for the synthetic gel by changing the dosage of the cross-linking agent, and change the ratio of the hydrophilic segment to the lipophilic segment.

Suitable monomers for the crosslinking agent proposed in the present invention are tert-butyl acrylate or monomers containing tert-butyl acrylate groups and styrene or monomers containing styrene groups.

Description of drawings

Figure 1 is the swelling curve of the amphiphilic gel in DMF and dichloromethane or a mixed solvent with a pH value of 12.91. Wherein the abscissa is the volume percentage of methylene chloride or lye, (●): lye (pH=12.91) (▲): methylene chloride.

Detailed ways:

1. Synthesis of cross-linking agent

1.11, Preparation of 4-bis(1-bromoethyl)benzene

In a 150 mL round bottom flask, 8.6 mL of 1,4-diethylbenzene (0.055 mol), 18.1 g of NBS (0.1 mol), 0.24 g of BPO (0.01 mol) and 54 mL of carbon tetrachloride were successively added. Under the protection of nitrogen, the oil bath was heated to about 90 degrees Celsius until the system was refluxed and reacted for 2 hours. When the NBS is completely consumed, a layer of white solid can be seen floating on the CCl ₄ . The system was cooled to room temperature, and the solids were removed by filtration. Atmospheric distillation removes carbon tetrachloride, and the crude product is milky white crystals. The crude product was recrystallized in petroleum ether (boiling range 90-120 degrees Celsius) to obtain a white solid with a yield of 53.5%. ¹ H NMR (CDCl ₃ ): δ 2.04 (d, 6H, CH ₃ ), 5.20 (q, 2H, CH), 7.41 (s, 4H, ArH).

1.2 Synthesis of 2,2,6,6-tetramethylpiperidine-1-oxyl acrylate (2,2,6,6-tetramethylpiperidine-1-oxyl acrylate)

15 g (0.087 mol) of 4-hydroxy-2,2,6,6-tetramethylpiperidine (HTEMPO) and 14.6 mL of triethylamine (0.105 mol) were dissolved in 150 mL of toluene. A mixed solution of 150 mL of toluene and 8.4 mL (0.105 mol) of acryloyl chloride was slowly added dropwise from a constant pressure dropping funnel under vigorous stirring at 0°C. The solution was stirred at 0° C. for 1 h, then warmed to room temperature and stirred for 24 h. The triethylamine hydrochloride produced by the reaction was removed by filtration, and the solution was washed with 50 mL of saturated NaHCO ₃ solution, deionized water and saturated saline three times respectively. The solution was then dried over anhydrous _MgSO4 overnight and concentrated on a rotary evaporator. The crude product was separated on a neutral alumina column (mobile phase was ethyl acetate:petroleum ether=1:5 (V/V)). The product was dark red crystals with a yield of 65%. IR: 1730 (C=O), 1370 (NO·), 995 (RCH=CH ₂ ); ESR: g=2.0063 G; MS(EI): (m/e)=226.

1.3 Synthesis of 1,4-cis-(1-(2,2,6,6-tetramethylpiperidine acrylate)ethyl)benzene (di-AET)

5.5 g ATEMPO (24 mmol), 1.46 g 1,4-bis(1-bromoethyl)benzene (5 mmol), 1.32 g cuprous bromide (10 mmol), 0.31 g Cu(0) (5 mmol) and 25 mL tetrahydrofuran were added 50mL in a branched-necked flask. After the system was freeze-thawed and degassed twice, 4.2 mL of pentamethyldiethylenetriamine (PMDETA) (20 mmol) was added. React at room temperature for 48 hours. The crude product was diluted with tetrahydrofuran, and the product was passed through a neutral alumina column to remove copper ions. The solution was concentrated on a rotary evaporator, and the crude product was separated by a neutral alumina column (the mobile phase was ethyl acetate:petroleum ether=1:5 (v/v)). The product was a white solid with a yield of 60%. ¹ H NMR (CDCl ₃ ) δ 0.60, 1.11, 1.27, and 1.34 (each br s, 24H, CH ₃ ), 1.48 (d, 8H, CH ₂ ), 1.74 -1.88 (complex m, 6H, CH ₃ ), 4.75 (d, 4H, CH), 5.07 (q, 4H, CH), 5.79 (d, 2H, CHH=CH), 6.08 (q, 2H, CH ₂ = CH), 6.37 (d, 2H, CHH=CH) and 7.25 (s, 4H, ArH). Calcd. _{for C34H52N2O6} : C, 69.83; H, 8.96 _; N, 4.79. Found: C, 70.02 _; H, 8.82; N, 4.45. MS (EI): (m/e) = 386.

2. Examples of amphiphilic gels synthesized by cross-linking agents

2.1 Synthesis of tert-butyl polyacrylate gel

Cuprous bromide (39.1 mg, 2.73×10 ^-4 mol), di-AET (0.32 g) and tert-butyl acrylate (4.00 mL, 2.73×10 ^-2 mol) were added to a glass test tube respectively. Seal the test tube with a rubber stopper, freeze-thaw and degas three times, and then fill it with nitrogen. Add pentamethyldiethylenetriamine PMDETA (6.0×10 ^-5 L, 2.9×10 ^-4 mol) with a microsampler and stir at room temperature for several minutes until the solution turns bright green, at which time the copper complex form. Then 2-bromo-2-isobutyryl bromide (MBP) (6.1×10 ^-5 L, 5.5×10 ^-4 mol) was added rapidly with a micro injector, and the temperature of the system was raised to 70°C. After reacting for 60 hours, the system was put into liquid nitrogen to stop the reaction. The product was extracted three times with tetrahydrofuran in a fat extractor at 100 degrees centigrade for 72 hours each time, and dried in a vacuum oven to obtain poly(tert-butyl acrylate) gel.

2.2 Synthesis of poly(tert-butylacrylate)-polystyrene diblock gel

Put 0.17g of tert-butyl polyacrylate gel into a test tube, add 4ml of styrene, swell at room temperature for 24 hours, freeze and thaw the system three times and degas it, then fill it with nitrogen, raise the temperature to 120 degrees Celsius and react for 4 to 60 hours. The test tube was dropped into liquid nitrogen to stop the reaction. The product was extracted three times with tetrahydrofuran in a fat extractor at 100 degrees centigrade, each time for 72 hours, and dried in a vacuum oven to obtain a polytert-butyl acrylate-polystyrene diblock gel.

2.3 Synthesis of polyacrylic acid-polystyrene amphiphilic block gel

Put 2.54g of polytert-butyl acrylate-polystyrene diblock gel (TBA1.0PS60h) into a spherical bottle, add 50ml of dichloromethane, and after swelling at room temperature for 8 hours, slowly add 2.50ml of three Fluoroacetic acid was stirred and reacted at room temperature for 8 hours, and the product was washed with tetrahydrofuran several times, dried in a vacuum oven, and weighed.

3. Swelling property test of amphiphilic gel

Because the amphiphilic block gel contains hydrophilic and hydrophobic segments, it will show different swelling curves from ordinary gels in different solvents. We mixed dichloromethane or sodium hydroxide solution with a pH value of 12.91 with nitrogen nitrogen dimethylformamide (DMF) at different volume percentage concentrations, and gave the swelling of amphiphilic gels in different solvents at 20 degrees Celsius For curves, see Figure 1. It can be seen from the figure that the swelling curve of the gel with the change of the solution percentage reflects the characteristics of the swelling curve of the amphiphilic gel, which is amphiphilic.

Claims (3)

1. A cross-linking agent for synthesizing amphiphilic gel, characterized in that the cross-linking agent is a bifunctional cross-linking agent containing tert-butyl acrylate group and alkoxylamine group, its structural formula as follows:

2. the preparation method of the linking agent proposed as claimed in claim 1 is characterized in that: utilize the method for atom transfer free radical addition, at first by 4-hydroxyl-2,2,6,6, tetramethylpiperidine and Triethylamine is reacted at a low temperature of -10 to 5°C to prepare tert-butyl acrylate derivatives containing nitroxide free radicals, and then the tert-butyl acrylate derivatives containing nitroxide free radicals and benzene containing binary halides The derivatives of the derivatives are subjected to atom transfer radical addition reaction at 15-40°C to obtain the required cross-linking agent. 3. the application of cross-linking agent proposed in claim 1 in synthesizing amphiphilic gel, it is characterized in that cross-linking agent at first and tert-butyl acrylate or a class of monomers containing tert-butyl acrylate group atom transfer occurs Free radical polymerization and copolymerization form poly(tert-butyl acrylate) gel, and the alkoxyamine group in poly(tert-butyl acrylate) gel triggers the nitrogen-oxygen-regulated free radical polymerization of styrene or a class of monomers containing styrene groups , so as to obtain poly(tert-butyl acrylate-polystyrene diblock gel), which is swollen in dichloromethane and then added with trifluoroacetic acid, wherein the poly(tert-butyl acrylate) segment is hydrolyzed into polyacrylic acid, thus obtaining two Aphilic polyacrylic acid-polystyrene diblock gel.

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