CN109942221A - Silane-modified graphene oxide chemically modified polycarboxylate water reducing agent and preparation method thereof - Google Patents

Abstract

The present invention relates to a kind of silane-modified graphene oxide modification type polycarboxylate water-reducers and preparation method thereof, and the water-reducing agent is prepared by the following method: γ-methacryloxypropyl trimethoxy silane is uniformly mixed to complete hydrolysis with the ethanol solution of 50% concentration into silanol groups；Graphene oxide, ultrasonic disperse to evenly dispersed and heating water bath is added；To but to room temperature, be filtered by vacuum pump to it and pass through ethanol solution and washed to it；Prepared silane-modified graphene oxide and isobutene alcohol polyoxyethylene ether are subjected to aqueous free radical polymerization reaction, obtain silane-modified graphene oxide chemical modification type polycarboxylate water-reducer.Compared with prior art, the present invention has many advantages, such as strong to cement-based material peptizaiton is newly mixed, significant to hardening cement base material reinforcing effect, and preparation process is simple, and raw material is easy to get, low in cost, is suitable for industrialized production.

Description

Silane-modified graphene oxide chemically modified polycarboxylate water reducing agent and preparation method thereof

technical field

The invention relates to a polycarboxylate water reducer and a preparation method thereof, in particular to a silane-modified graphene oxide chemically modified polycarboxylate water reducer and a preparation method thereof.

Background technique

Graphene oxide has the characteristics of large specific surface area and small pore size, and the lamella contains various functional groups. When incorporated into cement-based materials, it can fill the gaps of cement particles, reduce porosity and fix free water. Moreover, the oxygen-containing functional groups on the graphene oxide sheet provide active sites for the growth of cement hydration crystals, which can control the hydration products and aggregated structures, so that the shape and aggregate structure tend to be regular and ordered microstructures, thereby controlling the cement. Defect structures such as cracks and holes in the matrix and the cracking phenomenon caused by penetration can effectively improve the mechanical properties and durability of cement-based materials. However, the current problem is that graphene oxide is prone to agglomeration due to its small size and strong van der Waals forces and hydrogen bonds, which prevents graphene oxide from being uniformly dispersed in the cement matrix as lamellae, resulting in defects in cement-based materials. And the formed large aggregates reduce its specific surface area and affect its function in cement-based materials.

In order to solve the problem of uniform dispersion of graphene oxide in cement-based materials, it is necessary to prepare a graphene oxide dispersion with few lamellae, small size and uniform dispersion by chemical modification, so as to fundamentally achieve graphene oxide in cement The effect of uniform dispersion in the matrix.

Chinese patent 201310192111.2 discloses a preparation method of a silane-modified graphene oxide chemically modified polycarboxylate water reducer. The specific steps are as follows: firstly, graphite is pre-oxidized to prepare graphene oxide, then the graphene oxide solution and the polycarboxylate water reducer are stirred evenly, and then the graphene oxide modified polycarboxylate water reducer is obtained by ultrasonic treatment. The graphene oxide-modified polycarboxylate water-reducing agent prepared by the method is a physical modification, which may lead to the failure of the interaction between graphene oxide and the polycarboxylate water-reducing agent in different solution environments, thereby affecting the graphene oxide. Uniform dispersion and effective action in cement-based materials.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a silane-modified graphene oxide chemically modified polycarboxylate water reducer and a preparation method thereof in order to overcome the defects existing in the prior art.

The object of the present invention can be realized through the following technical solutions:

A preparation method of a silane-modified graphene oxide chemically modified polycarboxylate water-reducing agent, comprising the following steps:

(1) Mix γ-methacryloyloxypropyltrimethoxysilane with 50% concentration of ethanol solution uniformly, stir magnetically for 1 h in a water bath environment of 30-40°C, until γ-methacryloyloxypropyl The methoxysilane is completely hydrolyzed into silanol groups in the trimethoxysilane;

(2) adding graphene oxide to the mixed solution in step (1), and ultrasonically dispersing for 1 h until the graphene oxide is uniformly dispersed.

(3) The mixed solution in step (2) is magnetically stirred and heated in a water bath, the heating temperature is 80°C, and the time is 5h.

(4) Cool the mixed solution in step (3) to room temperature, filter it through a vacuum pump, and wash it 6 times through a 50% ethanol solution.

(5) mixing the silane-modified graphene oxide in step (4) with deionized water, and dispersing by ultrasonic for 1 h;

(6) adding the pre-dissolved isobutenol polyoxyethylene ether to the reaction system of step (5), then adding ammonium persulfate and hydrogen peroxide, mixing and stirring uniformly;

(7) the reaction system obtained in step (6) is heated, and the pre-dissolved methacrylic acid, L-ascorbic acid and mercaptopropionic acid are added dropwise to the reaction system simultaneously;

(4) after the dropwise addition is completed, fully stir the reaction system, then add a neutralizing base to neutralize to pH=6-7, to obtain the target product;

Isobutenol polyoxyethylene ether is based on 100 parts by weight, and the addition amounts of other raw materials are as follows: 10-15 parts of γ-methacryloyloxypropyltrimethoxysilane, 3-5 parts of graphene oxide, Ammonium sulfate 0.2-2 parts, hydrogen peroxide 0.5-1.2 parts, L-ascorbic acid 0.3-1.0 parts, mercaptopropionic acid 0.5-1.5 parts;

The rate of addition of pre-dissolved methacrylic acid, L-ascorbic acid and chain transfer agent in step (7) satisfies:

The methacrylic acid is controlled to be added dropwise within 1-2h; the L-ascorbic acid and chain transfer agent are added dropwise within half an hour after the dropwise addition of methacrylic acid;

The pre-dissolved methacrylic acid, L-ascorbic acid and chain transfer agent in step (7) are all aqueous solutions, and their mass concentrations are all 1-5%.

Preferably, methacrylic acid is controlled to be added dropwise within 1-2h; L-ascorbic acid and chain transfer agent are added dropwise within half an hour after the dropwise addition of methacrylic acid;

Preferably, the isobutenol polyoxyethylene ether is based on 100 parts by weight, and the addition amounts of other raw material components are as follows: 12-15 parts of γ-methacryloyloxypropyltrimethoxysilane, 4-5 parts of graphene oxide parts, 0.5-2 parts of ammonium persulfate, 1.0-1.2 parts of hydrogen peroxide, 0.5-1.0 parts of L-ascorbic acid, and 0.8-1.5 parts of mercaptopropionic acid.

Preferably, the neutralizing base is one or both of sodium hydroxide with a concentration of 30% or potassium hydroxide with a concentration of 30% by mass.

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

(1) By introducing siloxane with a chemical condensation reaction with graphene oxide and successfully grafting siloxane onto graphene oxide, graphene oxide rich in active double bonds is formed, and by combining with methacrylic acid The copolymerization reaction of monomer and isobutenol polyoxyethylene ether, the synthesis of silane-modified graphene oxide type polycarboxylate water reducer, fundamentally improve the dispersibility of graphene oxide in cement-based materials, and improve graphene oxide for new The negative impact of the workability of mixing cement-based materials, and the enhancement and optimization effect of graphene oxide on cement-based materials.

(2) The preparation process is simple, the raw materials are readily available, the cost is low, and the method is suitable for industrialized production, the production process is simple, and no toxic and harmful substances are discharged.

(3) The silane-modified graphene oxide chemically-modified polycarboxylate water-reducing agent of the present invention has both super strong adsorption-dispersibility and optimized regulation effect on the microstructure of cement hydration products, which can make fresh concrete work well, Good fluidity, at the same time, the pore distribution of hardened cement-based materials is uniform, the total porosity is low, and the hardened cement-based materials have high compactness, high mechanical strength and good durability.

Detailed ways

The following specific examples will describe the present invention in detail.

Example 1

A silane-modified graphene oxide chemically modified polycarboxylate water-reducing agent is prepared from the following components in parts by weight: 100 parts of isobutenol polyoxyethylene ether, γ-methacryloyloxypropyl trimethoxy 12 parts of monosilane, 5 parts of graphene oxide, 2 parts of ammonium persulfate, 1.0 part of hydrogen peroxide, 0.5 part of L-ascorbic acid, and 0.8 part of mercaptopropionic acid.

The concrete preparation method of above-mentioned water reducing agent is as follows:

Mix γ-methacryloyloxypropyltrimethoxysilane with 50% ethanol solution uniformly, stir magnetically for 1 hour in a water bath at 30-40°C until γ-methacryloyloxypropyltrimethoxysilane The methoxysilane in the base silane was completely hydrolyzed into silanol groups; graphene oxide was added to the mixed solution, and ultrasonically dispersed for 1 h until the graphene oxide was uniformly dispersed; the mixed solution was magnetically stirred and heated in a water bath at a heating temperature of 80 °C for a period of time. After the mixed solution was cooled to room temperature, it was filtered through a vacuum pump and washed 6 times with a 50% ethanol solution; the obtained silane-modified graphene oxide was mixed with deionized water, and dispersed by ultrasonic for 1 hour; Good isobutenol polyoxyethylene ether, then add ammonium persulfate and hydrogen peroxide, mix and stir evenly; heat the reaction system through a water bath (80 ° C), and at the same time pre-dissolved methacrylic acid, L-ascorbic acid and mercaptopropionic acid were added dropwise to the reaction system respectively; wherein, methacrylic acid was controlled to be added dropwise within 2h; L-ascorbic acid and chain transfer agent were added dropwise within half an hour after the dropwise addition of methacrylic acid; Stir well, and when the reaction system is cooled to room temperature, add neutralizing 30% NaOH solution to neutralize to pH=6.5, and then the target product is obtained.

Example 2

An anti-sulfate competitive adsorption type silane-modified polycarboxylate water reducer is prepared from the following components in parts by weight: 100 parts of isobutenol polyoxyethylene ether, γ-methacryloyloxypropyltrimethoxy 15 parts of base silane, 4 parts of graphene oxide, 0.5 part of ammonium persulfate, 1.2 part of hydrogen peroxide, 1.0 part of L-ascorbic acid, and 0.8 part of mercaptopropionic acid.

The concrete preparation method of above-mentioned water reducing agent is as follows:

Mix γ-methacryloyloxypropyltrimethoxysilane with 50% ethanol solution uniformly, stir magnetically for 1 hour in a water bath at 30-40°C until γ-methacryloyloxypropyltrimethoxysilane The methoxysilane in the base silane was completely hydrolyzed into silanol groups; graphene oxide was added to the mixed solution, and ultrasonically dispersed for 1 h until the graphene oxide was uniformly dispersed; the mixed solution was magnetically stirred and heated in a water bath at a heating temperature of 80 °C for a period of time. After the mixed solution was cooled to room temperature, it was filtered through a vacuum pump and washed 6 times with a 50% ethanol solution; the obtained silane-modified graphene oxide was mixed with deionized water, and dispersed by ultrasonic for 1 hour; Good isobutenol polyoxyethylene ether, then add ammonium persulfate and hydrogen peroxide, mix and stir evenly; heat the reaction system through a water bath (80 ° C), and at the same time pre-dissolved methacrylic acid, L-ascorbic acid and mercaptopropionic acid were added dropwise to the reaction system respectively; wherein, methacrylic acid was controlled to be added dropwise within 1.5h; L-ascorbic acid and chain transfer agent were added dropwise within half an hour after the dropwise addition of methacrylic acid; The system is fully stirred, and when the reaction system is cooled to room temperature, neutralized 30% NaOH solution is added to neutralize to pH=7, and the target product is obtained.

Example 3

An anti-sulfate competition adsorption type silane-modified polycarboxylate water reducer is prepared from the following components in parts by weight: 100 parts of isobutenol polyoxyethylene ether, γ-methacryloyloxypropyl trimeth 14 parts of oxysilane, 4.5 parts of graphene oxide, 1.0 parts of ammonium persulfate, 1.1 parts of hydrogen peroxide, 0.9 parts of L-ascorbic acid, and 1.3 parts of mercaptopropionic acid.

The concrete preparation method of above-mentioned water reducing agent is as follows:

Mix γ-methacryloyloxypropyltrimethoxysilane with 50% ethanol solution uniformly, stir magnetically for 1 hour in a water bath at 30-40°C until γ-methacryloyloxypropyltrimethoxysilane The methoxysilane in the base silane was completely hydrolyzed into silanol groups; graphene oxide was added to the mixed solution, and ultrasonically dispersed for 1 h until the graphene oxide was uniformly dispersed; the mixed solution was magnetically stirred and heated in a water bath at a heating temperature of 80 °C for a period of time. After the mixed solution was cooled to room temperature, it was filtered through a vacuum pump and washed 6 times with a 50% ethanol solution; the obtained silane-modified graphene oxide was mixed with deionized water, and dispersed by ultrasonic for 1 hour; good isobutenol polyoxyethylene ether, then put in ammonium persulfate and hydrogen peroxide, mix and stir evenly; heat the reaction system (80°C) through a water bath, and at the same time mix the pre-dissolved methacrylic acid, L-ascorbic acid and mercaptopropionic acid were added dropwise to the reaction system; wherein, the methacrylic acid was controlled to be added dropwise within 1 h; L-ascorbic acid and chain transfer agent were added dropwise within 0.5 h after the dropwise addition of methacrylic acid; Stir well, and when the reaction system is cooled to room temperature, add neutralizing 30% NaOH solution to neutralize to pH=6, to obtain the target product.

Example 4

The water-reducing agent obtained in the above examples 1-3 was measured according to GB/T8077-2000 "Concrete Admixture Homogeneous Test Method" to measure the fluidity over time of the cement paste, and the results are shown in Table 1. According to GB/T50080-2002, the flexural and compressive strength of cement mortar was tested. The results are shown in Table 2.

Table 1: The fluidity and time fluidity of cement paste mixed with polycarboxylate superplasticizer

Table 2 Mechanical strength of cement mortar mixed with polycarboxylate superplasticizer

The polycarboxylate water-reducing agent prepared in Example 1-3 was mixed into the cement slurry, and the fluidity of the cement slurry and the fluidity over time were shown in Table 1. It can be seen from Table 1 that the polycarboxylate water reducing agent prepared in Examples 1-3 has good dispersion performance and time-dependent dispersion retention performance on the cement slurry, and can have a good negative effect of graphene oxide on the workability of the cement slurry. In addition, the polycarboxylate water-reducing agent prepared in Example 1-3 was mixed into the cement mortar, and the 3d and 28d flexural and compressive strengths of the cement mortar were shown in Table 2. As can be seen from Table 2, Example 1-3 prepared The silane-modified graphene oxide chemically modified polycarboxylate superplasticizer has a significant enhancement effect on cement-based materials.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (3)

1. a preparation method of silane-modified graphene oxide chemically modified polycarboxylate water-reducing agent, is characterized in that, described polycarboxylate water-reducing agent is made by the following steps: (1) Mix γ-methacryloyloxypropyltrimethoxysilane with 50% concentration of ethanol solution uniformly, stir magnetically for 1 h in a water bath environment of 30-40°C, until γ-methacryloyloxypropyl The methoxysilane is completely hydrolyzed into silanol groups in the trimethoxysilane; (2) adding graphene oxide to the mixed solution in step (1), and ultrasonically dispersing for 1 h until the graphene oxide is uniformly dispersed. (3) The mixed solution in step (2) is magnetically stirred and heated in a water bath, the heating temperature is 80°C, and the time is 5h. (4) Cool the mixed solution in step (3) to room temperature, filter it through a vacuum pump, and wash it 6 times through a 50% ethanol solution. (5) mixing the silane-modified graphene oxide in step (4) with deionized water, and dispersing by ultrasonic for 1 h; (6) adding the pre-dissolved isobutenol polyoxyethylene ether to the reaction system of step (5), then adding ammonium persulfate and hydrogen peroxide, mixing and stirring uniformly; (7) the reaction system obtained in step (6) is heated, and the pre-dissolved methacrylic acid, L-ascorbic acid and mercaptopropionic acid are added dropwise to the reaction system simultaneously; (4) after the dropwise addition is completed, fully stir the reaction system, then add a neutralizing base to neutralize to pH=6-7, to obtain the target product; Isobutenol polyoxyethylene ether is based on 100 parts by weight, and the addition amounts of other raw materials are as follows: 10-15 parts of γ-methacryloyloxypropyltrimethoxysilane, 3-5 parts of graphene oxide, Ammonium sulfate 0.2-2 parts, hydrogen peroxide 0.5-1.2 parts, L-ascorbic acid 0.3-1.0 parts, mercaptopropionic acid 0.5-1.5 parts; The rate of addition of pre-dissolved methacrylic acid, L-ascorbic acid and chain transfer agent in step (7) satisfies: The methacrylic acid is controlled to be added dropwise within 1-2h; the L-ascorbic acid and chain transfer agent are added dropwise within half an hour after the dropwise addition of methacrylic acid; The pre-dissolved methacrylic acid, L-ascorbic acid and chain transfer agent in step (7) are all aqueous solutions, and their mass concentrations are all 1-5%. 2. the preparation method of a kind of silane-modified graphene oxide chemically modified polycarboxylate water-reducing agent according to claim 1, is characterized in that, isobutenol polyoxyethylene ether is timed by 100 parts by weight, and other raw material components The addition amount is as follows: 12-15 parts of γ-methacryloyloxypropyltrimethoxysilane, 4-5 parts of graphene oxide, 0.5-2 parts of ammonium persulfate, 1.0-1.2 parts of hydrogen peroxide, L-ascorbic acid 0.5-1.0 parts, mercaptopropionic acid 0.8-1.5 parts. 3. the preparation method of a kind of silane-modified graphene oxide chemically modified polycarboxylate water-reducing agent according to any one of claim 1, is characterized in that, described neutralizing alkali is sodium hydroxide or potassium hydroxide one or more of them.