CN105085838A - Preparation method of modified nanometer SiO2-AA-AM copolymer - Google Patents

Abstract

The present invention relates to a kind of preparation method of modified nano-SiO ₂ -AA-AM copolymer, and described preparation method comprises the following steps: (1) mix modified nano-SiO ₂ functional monomer, acrylamide and acrylic acid, and oxidize with hydrogen Adjust the pH value to 6.0-7.5 with sodium, add distilled water to form an aqueous solution with a total monomer mass concentration of 20.0-26.0%; add an initiator, protect it with nitrogen, and react at a temperature of 36.0-42.0°C; the reaction product is washed, The copolymer can be obtained after crushing and drying. In the copolymer of the present invention, nano- _SiO2 is introduced into the copolymer, amino groups are connected to the surface of nano- _SiO2 and then double bonds are connected, and it is polymerized with acrylic acid and acrylamide. The synthesized copolymer has a space network structure, and through Controlling the degree of modification on the surface of the modified nano- _SiO2 functional monomer optimizes the viscosity-increasing performance of the copolymer.

Description

Preparation method of modified nanometer SiO2-AA-AM copolymer

technical field

The invention relates to the technical field of polymer material preparation, more specifically, the invention relates to a preparation method of modified nanometer SiO ₂ -AA-AM copolymer.

Background technique

As a non-renewable resource, petroleum plays an important role in the fields of industry and national defense. In order to increase the production life of the oil field and increase the output of the oil field, the use of polymer flooding is an important technology. Polymer flooding refers to adding a small amount of polymer to the injected water to improve the sweep coefficient and recovery factor by increasing the viscosity of the water phase and reducing the permeability of the oil layer. At present, polymer flooding has entered the stage of industrialization in my country's Daqing Oilfield, Shengli Oilfield, Dagang Oilfield, Jilin Oilfield, and Henan Oilfield, and has achieved good oil-increasing effects.

At present, polyacrylamide and its derivatives are widely used in polymer flooding. This kind of polymer can achieve ideal oil enhancement effect when used in low-temperature and low-salinity reservoirs, but its enhanced oil recovery effect is greatly reduced when used in high-temperature and high-salinity reservoirs. Hyperbranched polymers have strong shear resistance and can establish high resistance coefficient and residual resistance coefficient in porous media. At present, hyperbranched polymers are mainly synthesized with organic matter as the inner core, and the number of branched chains of the synthesized hyperbranched polymers is small. Although the number of branch chains can be increased by increasing the algebra of the organic inner core, the higher the inner algebra, the larger the molecular size, and the poorer the injectability of hyperbranched polymers; in addition, the higher the inner algebra, the less side reactions The more it is, the regularity of the kernel will be difficult to control. Even if a series of separation and purification techniques can be used to obtain a more regular kernel, the production cost of the kernel will be high.

Contents of the invention

In order to solve the above-mentioned technical problems existing in the prior art, the object of the present invention is to provide a preparation method of modified nano-SiO ₂ -AA-AM copolymer.

In order to achieve the above object, the present invention adopts the following technical solutions:

A preparation method of modified nano- _SiO2 -AA-AM copolymer, characterized in that said preparation method comprises the following steps: (1) mixing modified nano- _SiO2 functional monomers, acrylamide and acrylic acid, and oxidizing with hydrogen Adjust the pH value to 6.0-7.5 with sodium, add distilled water to form an aqueous solution with a total monomer mass concentration of 20.0-26.0%; add an initiator, protect it with nitrogen, and react at a temperature of 36.0-42.0°C; the reaction product is washed, The copolymer can be obtained after crushing and drying.

Wherein, the structural formula of described copolymer is as follows:

Wherein, the initiator is a mixture of ammonium persulfate and sodium bisulfite, and the molar ratio of the two is 1:1.

Wherein, the mass of the initiator is 0.10-0.30 wt% of the total mass of the monomers.

Wherein, the mass ratio of acrylamide to acrylic acid in the monomer is 1.86-4.00, and the content of the modified nano- _SiO2 functional monomer is 0.1-0.8 wt%.

Wherein, the modified nano- _SiO2 functional monomer is prepared by a method comprising the following steps: (1) using nano- _SiO2 and 3-aminopropyltriethoxysilane in anhydrous toluene solution at 80-100°C , react more than 12h to obtain amino-modified nano-SiO ₂ , and control the content of amino groups on the surface of nano-SiO ₂ by controlling the amount of 3-aminopropyltriethoxysilane added; (2) utilize excess maleic anhydride React with amino-modified nano- _SiO2 to obtain modified nano- _SiO2 functional monomer with carbon-carbon double bond.

Wherein, in step (2), comprise the following operations: 1. add maleic anhydride in N, N-dimethylformamide solution, stir and dissolve to obtain mixed solution completely; _2. add N in amino-modified nano-SiO , N-dimethylformamide was stirred evenly to obtain a dispersion; ③Then the dispersion obtained in operation ② was added dropwise to the mixed solution obtained in operation ①, and then stirred at 70-80°C to complete the reaction, and the obtained reaction product was washed , filtering, and drying to obtain the modified nano-SiO ₂ grafted with carbon-carbon double bonds.

Wherein, the molar weight of amino groups on the surface of the amino-modified nano-SiO ₂ is 25-40% of the molar weight of hydroxyl groups on the surface of the nano-SiO ₂ before modification.

Compared with the prior art, the terpolymer oil displacement agent of the present invention has the following beneficial effects:

In the copolymer of the present invention, nano- _SiO2 is introduced into the copolymer, amino groups are connected to the surface of nano- _SiO2 and then double bonds are connected, and it is polymerized with acrylic acid and acrylamide. The synthesized copolymer has a space network structure, and through Controlling the degree of modification on the surface of the modified nano- _SiO2 functional monomer optimizes the viscosity-increasing performance of the copolymer.

Description of drawings

Figure 1 shows the effect of the modification degree of nano-SiO ₂ on the viscosity-increasing performance of the copolymer.

Figure 2 is the infrared spectrum of the modified nano-SiO ₂ -AM-AA copolymer.

Figure 3 is the hydrogen spectrum of copolymer 1.

FIG. 4 is the hydrogen spectrum of copolymer 2.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to illustrate the technical solution of the present invention, and are not used to limit the protection scope of the invention.

Embodiment 1 Modified nanometer SiO _The preparation of functional monomer

The modified nano- _SiO2 functional monomer described in this embodiment is prepared by a method comprising the following steps: (1) using nano- _SiO2 and 3-aminopropyltriethoxysilane (KH540) at 80°C in anhydrous In toluene solution, react for 12h to obtain amino-modified nano-SiO ₂ , and control the content of amino groups on the surface of nano-SiO ₂ by controlling the amount of 3-aminopropyltriethoxysilane added; (2) utilize excess maleic butene The dianhydride is reacted with amino-modified nano- _SiO2 to obtain a modified nano- _SiO2 functional monomer with carbon-carbon double bonds. Step (2) comprises the following operations: 1. in N, N-dimethylformamide solution, add maleic anhydride, stir and dissolve to obtain mixed solution completely; _2. add N, N in amino-modified nano-SiO -Stir the dimethylformamide evenly to obtain a dispersion; ③ Add the dispersion obtained in operation ② dropwise to the mixed solution obtained in operation ①, then stir at 75°C to complete the reaction, and the obtained reaction product is washed, filtered and dried Modified nano-SiO ₂ grafted with carbon-carbon double bonds can be obtained. Wherein, in step (2), can utilize hydrochloric acid-ethanol non-aqueous titration method to judge the nano- _SiO2 of amino modification Whether the amino group on the surface reacts completely. Before the reaction of step ( ₁ ), adopt Grignard reagent titration method to measure nanometer SiO Surface hydroxyl number, and after reaction, use hydrochloric acid-ethanol non _- aqueous titration method to measure nanometer SiO Content of surface amino group. Can prepare the nanometer _SiO2 functional monomer of different modification degree by embodiment 1 (can utilize the nanometer _SiO2 surface amino group of amino modification to account for the nanometer _SiO2 surface hydroxyl molarity percentage before modification to represent) .

Preparation of Example 2 Modified Nano SiO ₂ -AA-AM Copolymer

The preparation method of the modified nano- _SiO2 -AA-AM copolymer of the present embodiment comprises the following steps: (1) mixing the modified nano- _SiO2 functional monomer, acrylamide and acrylic acid, and adjusting the pH value to 7.0, add distilled water to make an aqueous solution with a total monomer mass concentration of 25.0%; when the temperature rises to 40°C, add an initiator, protect it with nitrogen, and react at a temperature of 40.0°C; the reaction product is washed, pulverized, and dried After that, the copolymer can be obtained. Wherein, the mass of the initiator is 0.20wt% of the total mass of the monomers, and the initiator is a mixture of ammonium persulfate and sodium bisulfite, and the molar ratio of the two is 1:1. The mass ratio of acrylamide to acrylic acid in the monomer is 3.2, and the content of the modified nano- _SiO2 functional monomer is 0.50 wt%. Different copolymers were prepared by using nano- _SiO2 functional monomers with different modification degrees to investigate its influence on the properties of the copolymers. Weigh the obtained copolymer powder, prepare the polymer solution with concentration of 2000mg/L with deionized water and 5000mg/L sodium chloride solution respectively, shear 20s with agitator (3600r/min), and then use BrookfieldDV-III The viscometer measures the viscosity of the polymer solution after shearing at 70.0°C, and the results are shown in Figure 1. It can be seen from Figure 1 that when the degree of modification of nano- _SiO2 is 30% and 35%, the copolymer solution prepared with deionized water and 5000mg/L sodium chloride solution has a higher viscosity after shearing. It can be seen that when the nano-SiO2 When the modification degree of _SiO2 is 30% and 35%, the synthesized copolymers have better viscosity-increasing properties.

Characterization of Modified Nano-SiO ₂ -AA-AM Copolymer

1. Infrared spectral analysis

① Vacuum dry the synthesized polymer at 40.4°C for 48 hours; ② Take a small amount of dried KBr and press it into tablets with an infrared tablet press; ③ Scan the infrared spectrum with a WQF-520 infrared spectrometer to collect the background of the instrument; ④ Take a small amount of polymer sample, add KBr and mix evenly, the mass ratio of KBr to sample is about 50:1; ⑤Compress the KBr with sample with infrared tablet machine; ⑥Use the prepared sample tablet with WQF-520 An infrared spectrometer was used to scan the infrared spectrum. The infrared spectra of modified nano-SiO ₂ -AM-AA copolymer 1 (the degree of modification of nano-SiO ₂ is 30%) and copolymer 2 (the degree of modification of nano-SiO ₂ is 35%) are shown in FIG. 2 . The absorption peak around 3409.2cm ^-1 is the characteristic peak of hydroxyl; the absorption peak around 2931.4cm ^-1 is the characteristic peak of methylene; the absorption peak around 1653.8cm ^-1 is the characteristic peak of carbonyl; at 1112.1cm The absorption peak near ^-1 is the asymmetric stretching vibration peak of Si-O-Si, and the absorption peak near 769.2cm ^-1 is the symmetrical stretching vibration peak of Si-O-Si. The above results indicated that the target copolymer was synthesized.

2. NMR Analysis

① Add the synthesized copolymer to the NMR tube; ② Add heavy water to the NMR tube and let it dissolve completely; ③ Scan the hydrogen spectrum of the product with a Bruker AC-E200 NMR spectrometer at a frequency of 200 Hz. The hydrogen spectra of modified nano-SiO ₂ -AM-AA copolymer 1 (the degree of modification of nano-SiO ₂ is 30%) and copolymer 2 (the degree of modification of nano-SiO ₂ is 35%) are shown in Figure 3 and Figure 4 respectively As shown, 1.5ppm is -CH ₂ -CH(COONa)-, -CH ₂ -CH(CONH ₂ )-, -CH(COONa)-CH(CONH-)-, -CH ₂ -CH ₂ -CH ₂ - NH-chemical shift of proton; 2.1ppm is -CH ₂ -CH(COONa)-, -CH ₂ -CH(CONH ₂ )-, -CH(COONa)-CH(CONH-)-chemical shift of proton; 3.4ppm is the chemical shift of the -CH ₂ -CH ₂ -CH ₂ -NH- proton. The above results indicated that the target copolymer was synthesized.

3. Determination of the absolute weight average molecular weight of the copolymer

Determination of Copolymer Molecular Weight by Static Light Scattering

(1) Experimental steps of static light scattering

① Filter the prepared polymer solution with a 0.8 μm filter membrane, dedust the polymer solution, prepare samples, and place them for 24 hours; ② Turn on the BI-200SM wide-angle dynamic/static laser scattering instrument and water bath (25.0°C), and let Preheat the instrument for more than 30 minutes; ③ Turn on the processor and laser transmitter. If there are many impurities, open the filter to filter the impurities to meet the experimental requirements, and adjust the laser intensity; ④ After the preparation is completed, use toluene as the calibration solution, and deduct The influence of the solvent, and then put into the polymer solution samples with different concentrations in turn for testing.

(3) Molecular weight of the copolymer

Filter deionized water with a 0.8 μm filter membrane, and dedust the deionized water; then prepare a series of polymer solutions with different concentrations (30, 40, 50, 60, 70mg/L) with the deionized water that has been dedusted. Then use a 0.8μm filter to remove dust. The polymers are AA/AM copolymer (HPAM), modified nano-SiO ₂ -AM-AA copolymer 1 and copolymer 2. At 25.0°C, the absolute weight-average molecular weight and radius of gyration of the polymer were measured by static light scattering experiments. Using the double extrapolation method, when the incident light angle and the concentration of the polymer solution are close to zero, the above Zimm diagram The reciprocal of the intersection point is the absolute weight average molecular weight of the copolymer. The results of the absolute weight average molecular weight and radius of gyration of the copolymer are shown in Table 1.

Table 1

polymer Radius of gyration (nm) Absolute weight average molecular weight (10 ⁷ g/mol) HPAM 129 1.24 Copolymer 1 98 0.98 Copolymer 2 95 0.95

Claims (8)

1. a kind of preparation method of modified nano-SiO ₂ -AA-AM copolymer, it is characterized in that described preparation method comprises the following steps: (1) modified nano-SiO ₂ functional monomer, acrylamide and acrylic acid are mixed, and use Adjust the pH value to 6.0-7.5 with sodium hydroxide, add distilled water to make an aqueous solution with a total monomer mass concentration of 20.0-26.0%; add an initiator, protect it with nitrogen, and react at a temperature of 36.0-42.0°C; the reaction product is passed through The copolymer can be obtained after washing, pulverizing and drying. 2. the preparation method of modified nano-SiO ₂ -AA-AM copolymer according to claim 1, is characterized in that the structural formula of described copolymer is as follows: 3. the preparation method of modified nanometer SiO ₂ -AA-AM copolymer according to claim 1 is characterized in that: described initiator is the mixture of ammonium persulfate and sodium bisulfite, and the mol ratio of the two It is 1:1. 4. The method for preparing the modified nano-SiO ₂ -AA-AM copolymer according to claim 3, characterized in that: the mass of the initiator is 0.10-0.30 wt% of the total mass of the monomers. 5. The preparation method of modified nano-SiO ₂ -AA-AM copolymer according to claim 1, characterized in that: the mass ratio of acrylamide to acrylic acid in the monomer is 1.86-4.00, and the modified nano-SiO ₂ The content of the functional monomer is 0.1-0.8wt%. 6. the preparation method of modified nano-SiO ₂ -AA-AM copolymer according to claim 1 is characterized in that: described modified nano-SiO ₂ functional monomer adopts the method comprising the following steps to prepare: 1) utilize Nano-SiO ₂ and 3-aminopropyltriethoxysilane were reacted in anhydrous toluene solution at 80-100°C for more than 12 hours to obtain amino-modified nano-SiO ₂ , and controlled 3-aminopropyltriethoxy The amount of addition of silane is used to control the content of amino groups on the surface of nano-SiO ₂ ; 2) the reaction of excessive maleic anhydride and amino-modified nano-SiO ₂ is obtained to have a modified nano-SiO ₂ functional monomer with carbon-carbon double bonds. 7. The preparation method of modified nanometer SiO ₂ -AA-AM copolymer according to claim 6 is characterized in that: in step 2) comprises the following operations: 1. in N, N-dimethylformamide solution, add Maleic anhydride, stirred and dissolved completely to obtain a mixed solution; ②Add N,N-dimethylformamide to the amino-modified nano- _SiO2 and stir evenly to obtain a dispersion; ③Then add the dispersion obtained in operation ② dropwise Put it into the mixed solution obtained in operation ①, and then stir it at 70-80°C to complete the reaction. After the obtained reaction product is washed, filtered and dried, the modified nano-SiO ₂ with carbon-carbon double bond can be obtained. 8. The preparation method of modified nano- _SiO2 -AA-AM copolymer according to claim 7, characterized in that: the nano- _SiO2 surface amino molar weight of the amino-modified nano-SiO2 is the nano- _SiO2 surface hydroxyl group before modification 25-40% of the molar weight.