阅读说明：本技术 一种早强型聚羧酸系减水剂及其制备方法 (Early-strength polycarboxylate water reducing agent and preparation method thereof ) 是由 彭荩影 钱珊珊 郑春扬 姜海东 黄春满 李伟 胡阳成 于 2020-07-06 设计创作，主要内容包括：本发明公开了一种早强型聚羧酸系减水剂及其制备方法,采用如下步骤制备：(1)将不饱和酸或其衍生物单体、不饱和聚醚大单体或不饱和酯类大单体在引发剂、还原剂和链转移剂共同作用下进行水相氧化-还原自由基聚合反应得到减水剂预聚产物；(2)将含胺基的金属-有机框架(MOF)纳米颗粒接枝到减水剂预聚产物的分子结构中,酰胺化反应得到早强型聚羧酸系减水剂。用本发明方法制备的聚羧酸系减水剂是一种早强型聚羧酸系减水剂,初期不影响高减水的前提下又能提高混凝土早期强度,产品性能稳定。(The invention discloses an early-strength polycarboxylic acid water reducer and a preparation method thereof, and the early-strength polycarboxylic acid water reducer is prepared by the following steps: (1) carrying out water-phase oxidation-reduction free radical polymerization on an unsaturated acid or derivative monomer thereof and an unsaturated polyether macromonomer or unsaturated ester macromonomer under the combined action of an initiator, a reducing agent and a chain transfer agent to obtain a water reducing agent prepolymerization product; (2) grafting metal-organic framework (MOF) nanoparticles containing amino to the molecular structure of a pre-polymerization product of the water reducing agent, and performing amidation reaction to obtain the early-strength polycarboxylic acid water reducing agent. The polycarboxylic acid water reducer prepared by the method is an early-strength polycarboxylic acid water reducer, can improve the early strength of concrete on the premise of not influencing high water reduction in the initial stage, and has stable product performance.)

1. An early strength type polycarboxylic acid water reducing agent, which has the following structure:

wherein, P is N, NH or O atom; r₁Is any one or combination of more of H, alkali metal ions, aliphatic groups, alicyclic groups or aromatic groups; r₂，R₃，R₄，R₆Respectively is any one or combination of more of H, aliphatic group, alicyclic group or aromatic group; r₅Is any one or combination of several of aliphatic group, alicyclic group or aromatic group; the polymerization degrees r and q are respectively 9-200, and the polymerization degrees n, m and p are respectively 10-100.

2. The early strength polycarboxylic acid water reducer according to claim 1, characterized in that the weight average molecular weight of the early strength polycarboxylic acid water reducer is 20000 to 80000 g/mol.

3. A preparation method of an early-strength polycarboxylic acid water reducer comprises the following steps:

(1) preparing a water reducing agent prepolymerization product: carrying out water-phase oxidation-reduction free radical polymerization reaction on an unsaturated acid or derivative monomer thereof, an unsaturated polyether macromonomer or an unsaturated ester macromonomer at 5-45 ℃ under the combined action of an initiator, a reducing agent and a chain transfer agent for 3-5 hours to obtain a water reducing agent prepolymerization product; wherein the molar ratio of the unsaturated acid or derivative monomer thereof, the unsaturated polyether macromonomer or unsaturated ester macromonomer, the initiator, the reducing agent and the chain transfer agent is 3-5: 1: 0.03-0.1: 0.03 to 0.2: 0.03 to 0.1;

(2) preparing an early strength polycarboxylic acid water reducer: carrying out amidation reaction on the water reducer prepolymer prepared in the step (1) and metal-organic framework MOF nanocrystals containing amino groups, and adding water after 0.5-5 h to obtain an early-strength polycarboxylate water reducer with the weight concentration of 10-60%; wherein the molar ratio of the water reducing agent prepolymerization product to the metal-organic framework MOF nanocrystal containing amino is 1: 1 to 10.

4. The method for preparing an early strength polycarboxylic acid water reducer according to claim 3, wherein the unsaturated acid or its derivative monomer in step (1) is one or a combination of two or more of acrylic acid, methacrylic acid, aconitic acid, maleic acid, itaconic acid, dimethyl maleic acid, 2-dimethyl-succinic acid, allyl succinic acid, 2-buten-1-ylsuccinic acid, and 1,2,3, 4-cyclopentenetetracarboxylic acid.

5. The preparation method of the early strength polycarboxylate water reducer according to claim 3, wherein the unsaturated polyether macromonomer or unsaturated ester macromonomer in step (1) is one or a combination of two or more of allyl polyethylene glycol, methallyl polyethylene glycol, prenol polyoxyethylene ether, isobutenol polyoxyethylene ether, methoxy polyethylene glycol methacrylate, methoxy polyethylene glycol acrylate, polyethylene glycol acrylate monoester and polyethylene glycol methacrylate, and the weight average molecular weight is 300-8000 g/mol.

6. The preparation method of the early strength polycarboxylate water reducer according to claim 3, wherein the initiator in step (1) is one or a combination of more than two of hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate.

7. The method for preparing the early strength polycarboxylic acid water reducing agent according to claim 3, wherein the reducing agent in step (1) is one or a combination of two or more of sodium bisulfite, sodium sulfite, sodium formaldehyde sulfoxylate, ascorbic acid, sodium ascorbate, isoascorbic acid and sodium hypophosphite.

8. The method for preparing the early strength type polycarboxylic acid water reducing agent according to claim 3, wherein the chain transfer agent in step (1) is one or a combination of two or more of thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, sodium methallylsulfonate and dodecanethiol.

9. The method for preparing the early strength type polycarboxylic acid water reducing agent according to claim 3, wherein the metal-organic compound containing amino group in the step (2)The structural formula of the framework MOF nanocrystals is:wherein M is a metal ion.

10. The preparation method of the early strength polycarboxylate water reducer according to claim 3 or 9, wherein the metal-organic framework MOF nanocrystals containing amine groups in step (2) are aluminum-organic framework MOF nanocrystals, magnesium-organic framework MOF nanocrystals or a combination of two of them.

Technical Field

The invention relates to the technical field of polycarboxylic acid water reducing agents for cement concrete, in particular to an early-strength polycarboxylic acid water reducing agent prepared by an amidation reaction of an MOF structure and free radical polymerization and a method.

Background

Metal-organic frameworks (MOFs), as a very promising class of crystalline microporous materials, can be designed in their structure according to the targeted properties based on the geometry of the organic linker and the coordination mode of the inorganic metal ions or metal ion clusters. One key structural feature of MOFs is ultra-high porosity (up to 90% free volume) and incredibly high internal surface area, which plays a crucial role in functional applications. Typically, porous MOFs exhibit microporous characteristics (<2nm), however the pore size can be tuned in the range of a few angstroms to a few nanometers by controlling the length of the rigid organic linker. The research of the MOF composite material provides reference for synthesizing a high-performance composite material with a complex structure.

A MOF composite (hybrid) material is a material consisting of one MOF and one or more different component materials, including other MOFs, whose properties are significantly different from the materials of the individual components. In the composite material, the advantages of the MOFs (structural adaptability and flexibility, high porosity and ordered crystalline pores) and various functional materials (unique optical, electrical, magnetic and catalytic properties) can be effectively combined, so that new physical or chemical properties which cannot be obtained by a single component can be obtained, and the original properties can be enhanced. The selection of suitable MOF materials can be achieved using existing porous crystal libraries; or may use a simulation tool as an effective screening method.

To date, MOF composites, whose properties cannot be exhibited by individual components, have been successfully prepared using active materials including metal nanoparticles/nanorods (MNPs/MNRs), oxides, Quantum Dots (QDs), Polyoxometallates (POMs), polymers, graphene, Carbon Nanotubes (CNTs), and biomolecules, among others. Moreover, they offer the great advantage of flexible design, with the possibility of customizing the material to an optimal design. By perfect knowledge of the combined ingredients, porosity, functionality and morphology, it is meant that each MOF based composite is a new material with specific functional properties.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide an early-strength polycarboxylic acid water reducer and a preparation method thereof, which improve the early-strength performance on the premise of high water reduction.

In order to realize the purpose, the invention adopts the following technical scheme:

the invention provides an early-strength polycarboxylic acid water reducing agent, which has the following structure:

wherein, P is N, NH or O atom; r₁Is any one or combination of more of H, alkali metal ions, aliphatic groups, alicyclic groups or aromatic groups; r₂，R₃，R₄，R₆Respectively is any one or combination of more of H, aliphatic group, alicyclic group or aromatic group; r₅Is any one or combination of several of aliphatic group, alicyclic group or aromatic group; the polymerization degrees r and q are respectively 9-200, and the polymerization degrees n, m and p are respectively 10-100.

In a preferable embodiment of the early strength type polycarboxylic acid water reducing agent of the present invention, the weight average molecular weight of the early strength type polycarboxylic acid water reducing agent is 20000 to 80000 g/mol.

The invention also provides a preparation method of the early-strength polycarboxylic acid water reducer, which comprises the following steps:

(1) preparing a water reducing agent prepolymerization product: carrying out water-phase oxidation-reduction free radical polymerization reaction on an unsaturated acid or derivative monomer thereof, an unsaturated polyether macromonomer or an unsaturated ester macromonomer at 5-45 ℃ under the combined action of an initiator, a reducing agent and a chain transfer agent for 3-5 hours to obtain a water reducing agent prepolymerization product; wherein the molar ratio of the unsaturated acid or derivative monomer thereof, the unsaturated polyether macromonomer or unsaturated ester macromonomer, the initiator, the reducing agent and the chain transfer agent is (3-5): 1: (0.03-0.1): (0.03-0.2): (0.03-0.1);

(2) preparing an early strength polycarboxylic acid water reducer: carrying out amidation reaction on the water reducing agent prepolymerization product prepared in the step (1) and metal-organic framework (MOF) nanocrystals containing amino, and adding water after 0.5-5 h to obtain an early strength polycarboxylic acid water reducing agent with the weight concentration of 10-60%; wherein the molar ratio of the water reducing agent prepolymerization product to the metal-organic framework (MOF) nanocrystal containing amino is 1: (1-10).

As a preferable embodiment of the preparation method of the present invention, the unsaturated acid or derivative monomer thereof in the step (1) is one or a combination of two or more of acrylic acid, methacrylic acid, aconitic acid, maleic acid, itaconic acid, dimethyl maleic acid, 2-dimethyl-succinic acid, allyl succinic acid, 2-buten-1-ylsuccinic acid, or 1,2,3, 4-cyclopentenetetracarboxylic acid.

As a preferable scheme of the preparation method, the unsaturated polyether macromonomer or unsaturated ester macromonomer in the step (1) is one or a combination of two or more of allyl polyethylene glycol, methallyl polyethylene glycol, isopentenol polyoxyethylene ether, isobutenol polyoxyethylene ether, methoxy polyethylene glycol methacrylate, methoxy polyethylene glycol acrylate, polyethylene glycol acrylate monoester and polyethylene glycol methacrylate, and the weight average molecular weight of the unsaturated polyether macromonomer or unsaturated ester macromonomer is 300-8000 g/mol.

As a preferable scheme of the preparation method, the initiator in the step (1) is one or a combination of more than two of hydrogen peroxide, ammonium persulfate, sodium persulfate and potassium persulfate.

In a preferable embodiment of the preparation method of the present invention, the reducing agent in step (1) is one or a combination of two or more of sodium bisulfite, sodium sulfite, sodium formaldehyde sulfoxylate, ascorbic acid, sodium ascorbate, isoascorbic acid, and sodium hypophosphite.

As a preferable scheme of the preparation method, the chain transfer agent in the step (1) is one or a combination of more than two of thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, sodium methallylsulfonate and dodecanethiol.

As a preferable scheme of the preparation method of the present invention, the structure of the metal-organic framework (MOF) nanocrystals containing amine groups in step (2) is simply represented by:wherein M is a metal ion, preferably one or a combination of two of aluminum-organic framework (MOF) nanocrystals, magnesium-organic framework (MOF) nanocrystals.

According to the invention, the MOF is grafted to the molecular structure of the polycarboxylic acid type concrete high-performance water reducing agent, compared with the traditional water reducing agent, the process is simple, and a new function is endowed to the water reducing agent.

The invention has the following beneficial effects:

1. the raw materials used by the invention have rich sources.

2. The polycarboxylic acid water reducing agent prepared by the invention can release aluminum/magnesium ions through a metal-organic framework (MOF) in a molecular structure under the alkaline condition of concrete to shorten the setting time of the concrete, thereby improving the early strength of the concrete.

3. The polycarboxylic acid water reducing agent product prepared by the invention has early strength performance on the premise of not influencing water reduction.

4. The preparation method disclosed by the invention is safe and reliable in the whole process of preparing the polycarboxylate superplasticizer product, simple and convenient in operation steps, free of organic solvent, non-toxic, pollution-free and environment-friendly.

5. The invention can adjust the product performance by controlling the molecular structure of the water reducing agent copolymerization product and the grafting quantity of metal-organic framework (MOF) nanocrystals; the research of the polycarboxylic acids high efficiency water reducing agent with MOF structure is a breakthrough of the traditional water reducing agent technology, and the designability of the molecular structure layer enables the polycarboxylic acids high efficiency water reducing agent to be capable of developing series products with different performance characteristics or novel structures so as to meet the diversified requirements of building engineering on concrete admixtures, thereby having wider development potential and market prospect.

6. The polycarboxylic acid water reducing agent prepared by the invention is stable in performance after being prepared into an aqueous solution, and is not layered or precipitated during storage.

Detailed Description

In order to make the technical objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described with reference to various embodiments.