CN102675564B - Method for efficient graft polymerization of glycidyl methacrylate on surface of silica gel particle - Google Patents

Abstract

The invention discloses a method for efficiently grafting glycidyl methacrylate on the surface of silica gel particles, and relates to a graft polymerization method for efficiently grafting PGMA on the surface of silica gel particles. The method comprises the following steps: modifying the surface of the activated silica gel with γ-mercaptopropyltrimethoxysilane to obtain MPMS-SiO ₂ modified silica gel particles containing mercapto groups on _the surface; Mix base formamide and glycidyl methacrylate, add initiator BPO, carry out graft polymerization under constant temperature and stirring conditions, and obtain grafted particles PGMA/SiO ₂ . The invention utilizes the graft polymerization initiated by the mercapto-BPO system, has high grafting degree because the active site is located on the surface of the carrier, and realizes the high-efficiency graft polymerization of the oil-soluble monomer GMA on the surface of the silica gel.

Description

A method for high-efficiency graft polymerization of glycidyl methacrylate on the surface of silica gel particles

technical field

The invention relates to a graft polymerization method for efficiently grafting PGMA on the surface of silica gel particles, in particular to a method for realizing high-efficiency graft polymerization of glycidyl methacrylate on the surface of silica gel particles by using a mercapto-BPO redox initiation system.

Background technique

Grafting functional macromolecules on the surface of inorganic particles to combine the functionality of functional macromolecules with the excellent physical and chemical properties of inorganic particles is an important way to prepare functional composite particles. Grafting functional macromolecules on the surface of inorganic particles (micron and nanoscale) can endow the particles with many new characteristics, such as adsorption performance, chemical activity, biological activity, biocompatibility, optical activity and dispersibility, etc., which can be widely used It is used in many scientific research and practical application fields such as chromatographic stationary phase, heterogeneous catalysis, enzyme immobilization, separation of biomacromolecules, high-performance adsorption materials, sensor construction, and reinforcement and toughening of plastics.

Glycidyl methacrylate (GMA) is an epoxy group-containing ethylenic monomer, and polymer macromolecules with epoxy groups can be prepared by homopolymerization or copolymerization. Epoxy group is a kind of active group, which can undergo ring-opening reaction with various groups such as carboxyl group, hydroxyl group and amino group, and transform GMA polymer into various functional macromolecules. Therefore, grafting GMA on the surface of solid particles can form a variety of functional grafted particles, which are widely used in many scientific and technological fields. For example, preparation of chelating materials and adsorbents for solid phase extraction, separation and purification of biomacromolecules, environmental treatment, and chromatographic fixation; preparation of immobilized catalysts for heterogeneous catalysis; preparation of functional carriers, It is used to build a slow and controlled release system for drugs; it can also build a host-guest system for molecular recognition and biosensor construction, etc. In conclusion, the graft polymerization of GMA on the surface of solid particles has important scientific value.

The method of grafting macromolecules on the surface of solid particles by chemical grafting can be divided into "grafting onto" (Grafting onto) method and "grafting from" (grafting from) method. The former is through the chemical reaction between the polymer terminal functional group and the surface active group of the particle material, and the polymer is coupled and grafted to the surface of the particle, so it is also called coupling grafting (coupling graft) method; the latter is through The introduction of polymerizable active sites (or polymerizable double bonds or initiating groups) on the surface of particulate materials allows monomers to polymerize from the surface of the particles to achieve graft polymerization. The "grafting" method has the advantage of high grafting degree, so it is widely used.

In the "grafting out" method, if the initiating group is introduced on the surface of the solid particle, the efficiency of graft polymerization is higher because the initiating species is located on the surface of the particle. However, since the modifiable groups on the surface of solid particles are often covered, special activation treatment is required to expose these groups, so it is often difficult to introduce initiating groups on the surface of solid particles.

Contents of the invention

The purpose of the present invention is to provide a method for high-efficiency graft polymerization of glycidyl methacrylate on the surface of silica gel particles.

According to the idea of molecular design, the present invention manages to introduce mercapto groups into the surface of micron-sized silica gel particles to form a mercapto-benzoyl peroxide (BPO) redox initiation system, generate free radicals on the surface of silica gel particles, and realize glycidyl methacrylate (GMA) graft polymerization on the surface of silica gel to prepare composite particles PGMA/SiO ₂ with high grafting degree.

The present invention is achieved through the following technical solutions:

A method for high-efficiency graft polymerization of glycidyl methacrylate on the surface of silica gel particles, comprising the following steps:

(1) Mercapto group modification on the surface of activated silica gel: add 2-3g activated silica gel to 125mL toluene, and add 2-3mL γ-mercaptopropyltrimethoxysilane (MPMS), react at 110-115°C for 10 -12h, the product after suction filtration was repeatedly washed with toluene, then washed with ethanol, and dried in vacuum to obtain modified silica gel particles MPMS-SiO ₂ containing mercapto groups on the surface;

(2) Graft polymerization of glycidyl methacrylate: Add 1-2g MPMS-SiO ₂ to a four-neck flask equipped with an electric stirrer, reflux condenser and thermometer, and then add 70mL N, N-dimethylformaldehyde Amide DMF and 7-9mL glycidyl methacrylate (monomer GMA), blow nitrogen for 30 minutes to remove the air in the system, then raise the temperature of the system to 55°C, add 0.08-0.09g initiator BPO, keep the temperature and Carry out the graft polymerization reaction under stirring conditions, after the reaction is finished, suction filtration, the product particles are extracted with acetone in a Soxhlet extractor for 24 hours, to remove the polymer physically adsorbed on the surface of the particles, and then vacuum-dried, that is The grafted microparticles PGMA/SiO ₂ were obtained.

Under the action of the mercapto-BPO initiator system, the reaction process of the graft polymerization initiated on the surface of the monomer GMA is shown in Figure 1.

The infrared spectra of three kinds of particulate SiO ₂ , MPMS-SiO ₂ and PGMA/SiO ₂ are shown in Figure 2. It can be seen from the figure that compared with the infrared spectrum of SiO ₂ , the modified particulate MPMS-SiO ₂ In the infrared spectrogram, the absorption peak related to silanol near 3440cm ^-1 has been greatly weakened. At the same time, the stretching vibration absorption peak of the mercapto SH bond appeared at 2566cm ^-1 , and the non-CH bond at 2920cm ^{-1 The} absorption peak of symmetrical stretching vibration is obviously strengthened, indicating that the coupling agent MPMS has reacted with the silicon hydroxyl _group and has been bonded on the surface of silica gel particles ^. The characteristic absorption peaks of epoxy group and ester carbonyl group of PGMA appeared in ¹ place, which fully indicated the formation of grafted particle PGMA/SiO ₂ .

The scanning electron micrographs of _SiO2 particles and grafted particles PGMA/ _SiO2 are shown in Figures 3 and 4. It can be seen from Figure 3 that the surface of _SiO2 particles before grafting is rough and uneven; and it can be seen from Figure 4 , the surface of SiO ₂ particles obviously becomes smoother after grafting, which is due to the filling and covering effect of polystyrene grafted on the surface of silica gel.

The thermogravimetric spectrum of modified microparticle MPMS- _SiO2 and grafted microparticle PGMA/ _SiO2 is shown in Figure 5, which is analyzed by the general method of thermogravimetric line of inorganic microparticle grafted polymer system: from the figure It can be seen that both the modified particle MPMS-SiO ₂ and the grafted particle PGMA/SiO ₂ decompose and lose weight at around 140°C (previously it was the volatilization weight loss of adsorbed water), and the modified particle is completely decomposed at 730°C, with a weight loss of 10.73%, corresponding to The amount of bonds to the coupling agent MPMS (consistent with the results of the iodometric method); the grafted particles were decomposed at 750°C, and the weight loss was 33.78%.

Compared with the prior art, the present invention has the following advantages:

The invention utilizes the graft polymerization initiated by the mercapto-BPO system, has high grafting degree because the active site is located on the surface of the carrier, and realizes the high-efficiency graft polymerization of the oil-soluble monomer GMA on the surface of the silica gel.

Description of drawings

Fig. 1 is the chemical reaction process of the grafting process of glycidyl methacrylate on the surface of silica gel;

Figure 2 is the infrared spectrum of three kinds of particles SiO ₂ , MPMS-SiO ₂ and PGMA/SiO ₂ ;

Figure 3 is a scanning electron microscope of SiO _particles ;

Fig. 4 is the scanning electron microscope of graft particle PGMA/SiO ₂ ;

Fig. 5 is the thermogravimetric spectrum of modified particle MPMS-SiO ₂ and grafted particle PGMA/SiO ₂ .

Detailed ways

Example 1

A method for high-efficiency graft polymerization of glycidyl methacrylate on the surface of silica gel particles, comprising the following steps:

(1) Mercapto group modification on the surface of activated silica gel: Add 2g of activated silica gel to 125mL of toluene, and add 2mL of γ-mercaptopropyltrimethoxysilane (MPMS), react at 110°C for 11h, and the product after suction filtration Repeatedly washing with toluene, then washing with ethanol, and drying in vacuum, the modified silica gel particles MPMS-SiO ₂ containing mercapto groups on the surface are obtained;

(2) Graft polymerization of glycidyl methacrylate: Add 1g of MPMS-SiO ₂ to a four-necked flask equipped with an electric stirrer, reflux condenser and thermometer, and then add 70mL of N, N-dimethylformamide DMF and 7.5mL of glycidyl methacrylate (monomer GMA), blow nitrogen for 30 minutes to remove the air in the system, then raise the temperature of the system to 55°C, add 0.08g of initiator BPO, keep the temperature constant and carry out under stirring conditions Grafting polymerization reaction, after the reaction, suction filtration, the product particles were extracted with acetone in a Soxhlet extractor for 24 hours to remove the polymer physically adsorbed on the surface of the particles, and then vacuum-dried to obtain grafted particles PGMA /SiO ₂ .

The degree of grafting of PGMA on the surface of grafted particle PGMA/SiO ₂ was measured by thermogravimetric method to be 24.4g/100g.

Example 2

A method for high-efficiency graft polymerization of glycidyl methacrylate on the surface of silica gel particles, comprising the following steps:

(1) Activation of silica gel: Take 30g of silica gel particles and put them in 150mL of 8% methanesulfonic acid aqueous solution, stir and activate at reflux temperature for 8h, the activated silica gel is washed repeatedly with distilled water until neutral, suction filtered, vacuum Dry to obtain activated silica gel;

(2) Mercapto group modification on the surface of activated silica gel: Add 3g of activated silica gel to 125mL of toluene, and add 3mL of γ-mercaptopropyltrimethoxysilane (MPMS), react at 115°C for 12h, and the product after suction filtration Repeatedly washing with toluene, then washing with ethanol, and drying in vacuum, the modified silica gel particles MPMS-SiO ₂ containing mercapto groups on the surface are obtained;

(3) Graft polymerization of glycidyl methacrylate: add 2g MPMS-SiO ₂ to a four-neck flask equipped with an electric stirrer, reflux condenser and thermometer, and then add 70mL N, N-dimethylformamide DMF and 9mL glycidyl methacrylate (monomer GMA), blow nitrogen for 30 minutes to remove the air in the system, then raise the temperature of the system to 55°C, add 0.09g initiator BPO, keep the temperature constant and carry out the inoculation under stirring conditions. Branch polymerization reaction, after the reaction, suction filtration, the product particles were extracted with acetone in a Soxhlet extractor for 24 hours to remove the polymer physically adsorbed on the surface of the particles, and then vacuum-dried to obtain the grafted particles PGMA/ SiO ₂ .

Example 3

A method for high-efficiency graft polymerization of glycidyl methacrylate on the surface of silica gel particles, comprising the following steps:

(1) Activation of silica gel: Take 30g of silica gel particles and place them in 150mL of 5% methanesulfonic acid aqueous solution, stir and activate at reflux temperature for 10h, wash the activated silica gel repeatedly with distilled water until neutral, suction filter, vacuum Dried to obtain activated silica gel;

(2) Mercapto group modification on the surface of activated silica gel: add 2.5g activated silica gel to 125mL toluene, and add 2mL of γ-mercaptopropyltrimethoxysilane (MPMS), react at 113°C for 10h, and the The product is washed repeatedly with toluene, then with ethanol, and dried in vacuum to obtain modified silica gel particles MPMS-SiO ₂ containing mercapto groups on the surface;

(3) Graft polymerization of glycidyl methacrylate: add 1.5g MPMS-SiO ₂ to a four-neck flask equipped with an electric stirrer, reflux condenser and thermometer, and then add 70mL N,N-dimethylformamide DMF and 8mL glycidyl methacrylate (monomer GMA), blow nitrogen for 30 minutes to remove the air in the system, then raise the temperature of the system to 55°C, add 0.08g initiator BPO, keep the temperature and carry out under stirring conditions Grafting polymerization reaction, after the reaction, suction filtration, the product particles were extracted with acetone in a Soxhlet extractor for 24 hours to remove the polymer physically adsorbed on the surface of the particles, and then vacuum-dried to obtain grafted particles PGMA /SiO ₂ .

Example 4

A method for high-efficiency graft polymerization of glycidyl methacrylate on the surface of silica gel particles, comprising the following steps:

(1) Modification of mercapto groups on the surface of activated silica gel: add 2.5g of activated silica gel to 125mL of toluene, and add 2mL of γ-mercaptopropyltrimethoxysilane (MPMS), react at 115°C for 10h, and the The product is washed repeatedly with toluene, then with ethanol, and dried in vacuum to obtain modified silica gel particles MPMS-SiO ₂ containing mercapto groups on the surface;

(2) Graft polymerization of glycidyl methacrylate: add 1.5g MPMS-SiO ₂ to a four-necked flask equipped with an electric stirrer, reflux condenser and thermometer, and then add 70mL N,N-dimethylformamide DMF and 7mL glycidyl methacrylate (monomer GMA), blow nitrogen for 30 minutes to remove the air in the system, then raise the temperature of the system to 55°C, add 0.08g initiator BPO, keep the temperature and carry out under stirring conditions Grafting polymerization reaction, after the reaction, suction filtration, the product particles were extracted with acetone in a Soxhlet extractor for 24 hours to remove the polymer physically adsorbed on the surface of the particles, and then vacuum-dried to obtain grafted particles PGMA /SiO ₂ .

Claims (1)

1. A method for efficient graft polymerization of glycidyl methacrylate on the surface of silica gel particles, characterized in that it comprises the following steps: (1) Mercapto group modification on the surface of activated silica gel: add 2-3g activated silica gel to 125mL toluene, and add 2-3mL γ-mercaptopropyltrimethoxysilane, react at 110-115°C for 10-12h, The product after suction filtration was repeatedly washed with toluene, then washed with ethanol, and dried in vacuum to obtain modified silica gel particles MPMS- _SiO2 containing mercapto groups on the surface; (2) Graft polymerization of glycidyl methacrylate: Add 1-2g MPMS-SiO ₂ to a four-neck flask equipped with an electric stirrer, reflux condenser and thermometer, and then add 70mL N, N-dimethylformaldehyde Amide DMF and 7-9mL glycidyl methacrylate, blow nitrogen for 30 minutes to remove the air in the system, then raise the temperature of the system to 55°C, add 0.08-0.09g initiator BPO, keep the temperature and carry out under stirring conditions Grafting polymerization reaction, after the reaction, suction filtration, the product particles were extracted with acetone in a Soxhlet extractor for 24 hours to remove the polymer physically adsorbed on the surface of the particles, and then vacuum-dried to obtain grafted particles PGMA /SiO ₂ .

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