Method for preparing pH-responsive graft copolymer taking ethyl cellulose as main chain

Abstract

The invention belongs to the fields of high polymer materials and biomedical engineering and particularly relates to a method for preparing pH-responsive graft copolymer taking ethyl cellulose as a main chain. The method comprises the following steps of: performing esterification reaction on residual hydroxyl in the ethyl cellulose main chain and a bromine-containing compound under the protection of inert gas nitrogen or argon to convert the hydroxyl into a bromine group; and performing atom transfer radical polymerization on a methacrylic acid-N,N-lignocaine ethyl ester monomer by using the bromine group as a macroinitiator to form pH-responsive polymer so as to finally obtain the pH-responsive graft copolymer taking the ethyl cellulose as the main chain. The pH-responsive graft copolymer taking the ethyl cellulose as the main chain has biodegradability, biocompatibility and pH value sensitivity and can be self-assembled into stable nano micelles in water, so the pH-responsive graft copolymer can be widely applied to the fields such as medicament release control carriers, biological intelligent switches, biological sensors, biological nano devices and the like. The method has the advantages of simpleness, practicability, industrialized production of raw materials and high popularization and application value.

Description

technical field

[0001] The invention belongs to the fields of polymer materials and biomedical engineering, and in particular relates to a preparation method of a pH-responsive graft copolymer with ethyl cellulose as the main chain. Background technique

[0002] Ethyl cellulose is an important derivative of cellulose, the most abundant natural biopolymer material in nature, and it is biocompatible and biodegradable. However, the structure of ethyl cellulose is relatively simple, and its function is relatively single, which can no longer meet the higher application requirements. It needs to be modified by physical and chemical methods to expand its function. Yuan Jinying et al. (Yuan, W. Z.; Yuan, J. Y.; Zhang, F. B.; Xie, X. M. Biomacromolecules, 2007, 8, 1101-1108.) prepared ethyl cellulose as the main chain by stepwise ring-opening polymerization. Graft copolymer of caprolactone and polylactide block copolymer; Huang Yong et al. (Kang, H. L.; Liu, W. Y.; He, B. Q.; Shen, ...

Examples

Embodiment 1

[0020] Weigh 6 grams of ethyl cellulose, dissolve it in dichloromethane, add 2 grams of triethylamine, add 4 grams of 2-bromoisobutyryl bromide dropwise at -5°C, drop it in 20 minutes, and put it at 10°C Reaction for 72 hours. After desalination by suction filtration, precipitation with deionized water, and vacuum drying to obtain a bromo-terminated ethyl cellulose macromolecular initiator. Weigh 0.1 g of bromo-terminated ethyl cellulose macroinitiator and dissolve it in N,N-dimethylformamide, add 2 g of N,N-diethylaminoethyl methacrylate, and then add the initiator bromine Cuprous chloride (40 mg) / hexamethyltriethylenetetramine (75 mg) was vacuum-filled three times with nitrogen, and reacted at 20°C for 48 hours under nitrogen protection. The product was dialyzed with deionized water and freeze-dried to obtain a pH-responsive graft copolymer with ethyl cellulose as the main chain.

[0021] The representative structural formula of the pH-responsive graft copolymer with ethyl...

Embodiment 2

[0023] Weigh 6 grams of ethyl cellulose, dissolve it with N,N-dimethylformamide, add 4 grams of diethylamine, add 8 grams of 2-bromoisobutyryl bromide dropwise at 0°C, and drop it in 30 minutes. And react at 15°C for 60 hours. After desalination by suction filtration, precipitation with deionized water, and vacuum drying to obtain a bromo-terminated ethyl cellulose macromolecular initiator. Weigh 0.1 g of bromo-terminated ethyl cellulose macroinitiator and dissolve it in N,N-dimethylacetamide, add 4 g of N,N-diethylaminoethyl methacrylate, and then add the initiator chlorine Cuprous chloride (50 mg) / bipyridine (90 mg) was vacuum-filled three times with nitrogen, and reacted at 30°C for 24 hours under nitrogen protection. The product was dialyzed with deionized water and freeze-dried to obtain a pH-responsive graft copolymer with ethyl cellulose as the main chain.

Embodiment 3

[0025] Weigh 6 grams of ethyl cellulose, dissolve it in chloroform, add 6 grams of triethylamine, add 10 grams of 2-bromopropionyl bromide dropwise at 5°C, drop it in 35 minutes, and react at 20°C for 40 hours. After desalting by suction filtration, it was precipitated by methanol and dried in vacuum to obtain a bromo-terminated ethyl cellulose macroinitiator. Weigh 0.1 g of the bromo-terminated ethyl cellulose macroinitiator and dissolve it in anisole, add 6 g of N,N-diethylaminoethyl methacrylate, and then add the initiator cuprous bromide (60 mg ) / pentamethyldiethylenetriamine (80 mg), through the process of vacuumizing-nitrogen gas three times, and reacting in an oil bath at 40°C for 12 hours under the protection of nitrogen gas. The product was dialyzed with deionized water and freeze-dried to obtain a pH-responsive graft copolymer with ethyl cellulose as the main chain.

technical field

[0001] The invention belongs to the fields of polymer materials and biomedical engineering, and in particular relates to a preparation method of a pH-responsive graft copolymer with ethyl cellulose as the main chain. Background technique

[0002] Ethyl cellulose is an important derivative of cellulose, the most abundant natural biopolymer material in nature, and it is biocompatible and biodegradable. However, the structure of ethyl cellulose is relatively simple, and its function is relatively single, which can no longer meet the higher application requirements. It needs to be modified by physical and chemical methods to expand its function. Yuan Jinying et al. (Yuan, W. Z.; Yuan, J. Y.; Zhang, F. B.; Xie, X. M. Biomacromolecules, 2007, 8, 1101-1108.) prepared ethyl cellulose as the main chain by stepwise ring-opening polymerization. Graft copolymer of caprolactone and polylactide block copolymer; Huang Yong et al. (Kang, H. L.; Liu, W. Y.; He, B. Q.; Shen, ...

Examples

Embodiment 1

[0020] Weigh 6 grams of ethyl cellulose, dissolve it in dichloromethane, add 2 grams of triethylamine, add 4 grams of 2-bromoisobutyryl bromide dropwise at -5°C, drop it in 20 minutes, and put it at 10°C Reaction for 72 hours. After desalination by suction filtration, precipitation with deionized water, and vacuum drying to obtain a bromo-terminated ethyl cellulose macromolecular initiator. Weigh 0.1 g of bromo-terminated ethyl cellulose macroinitiator and dissolve it in N,N-dimethylformamide, add 2 g of N,N-diethylaminoethyl methacrylate, and then add the initiator bromine Cuprous chloride (40 mg) / hexamethyltriethylenetetramine (75 mg) was vacuum-filled three times with nitrogen, and reacted at 20°C for 48 hours under nitrogen protection. The product was dialyzed with deionized water and freeze-dried to obtain a pH-responsive graft copolymer with ethyl cellulose as the main chain.

[0021] The representative structural formula of the pH-responsive graft copolymer with ethyl...

Embodiment 2

[0023] Weigh 6 grams of ethyl cellulose, dissolve it with N,N-dimethylformamide, add 4 grams of diethylamine, add 8 grams of 2-bromoisobutyryl bromide dropwise at 0°C, and drop it in 30 minutes. And react at 15°C for 60 hours. After desalination by suction filtration, precipitation with deionized water, and vacuum drying to obtain a bromo-terminated ethyl cellulose macromolecular initiator. Weigh 0.1 g of bromo-terminated ethyl cellulose macroinitiator and dissolve it in N,N-dimethylacetamide, add 4 g of N,N-diethylaminoethyl methacrylate, and then add the initiator chlorine Cuprous chloride (50 mg) / bipyridine (90 mg) was vacuum-filled three times with nitrogen, and reacted at 30°C for 24 hours under nitrogen protection. The product was dialyzed with deionized water and freeze-dried to obtain a pH-responsive graft copolymer with ethyl cellulose as the main chain.

Embodiment 3

[0025] Weigh 6 grams of ethyl cellulose, dissolve it in chloroform, add 6 grams of triethylamine, add 10 grams of 2-bromopropionyl bromide dropwise at 5°C, drop it in 35 minutes, and react at 20°C for 40 hours. After desalting by suction filtration, it was precipitated by methanol and dried in vacuum to obtain a bromo-terminated ethyl cellulose macroinitiator. Weigh 0.1 g of the bromo-terminated ethyl cellulose macroinitiator and dissolve it in anisole, add 6 g of N,N-diethylaminoethyl methacrylate, and then add the initiator cuprous bromide (60 mg ) / pentamethyldiethylenetriamine (80 mg), through the process of vacuumizing-nitrogen gas three times, and reacting in an oil bath at 40°C for 12 hours under the protection of nitrogen gas. The product was dialyzed with deionized water and freeze-dried to obtain a pH-responsive graft copolymer with ethyl cellulose as the main chain.

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