Four-arm star-shaped block polycarboxylic acid super-plasticizer and preparation method and application thereof

Abstract

The invention discloses a four-arm star-shaped block polycarboxylic acid super-plasticizer and a preparation method and application thereof. A molecule with four hydroxyls is first terminated with a halogenated carboxylic acid derivative, then a halogen-containing terminated four-arm molecule is used as a structural core and a non-traditional unsaturated carboxylic acid derivative is used as an arm to prepare a polymer, and finally the star-shaped four-arm block super-plasticizer is synthesized after acid hydrolysis and separation and purification. The conventional unsaturated carboxylic acidis not used for polymerization, the controllability of the structure can be improved, and the irritation of the unsaturated carboxylic acid in production is reduced. A synthesized water-reducing agenthas excellent molecular structure controllability. The product is solid, has low blending amount, high dispersibility and high fluidity, and has the characteristics of convenient transportation and storage, low water absorption and low corrosivity.

Description

technical field [0001] The invention belongs to the field of superplasticizers, and in particular relates to a four-arm star-shaped block polycarboxylic acid superplasticizer and its preparation method and application. Background technique [0002] Because polycarboxylate superplasticizer (PCE) has the characteristics of low dosage and high water reducing rate (>40%), it can significantly improve the working performance, mechanical properties and durability of concrete, and has become a high-performance or ultra-high-performance concrete. One of the essential components in mix design. [0003] The polycarboxylate high-performance superplasticizers currently produced in industry are mainly composed of unsaturated monomers containing carboxyl groups, unsaturated polyethers and other monomers through free radical copolymerization. Acid group, ammonium group, multi-branched comb structure polymer of polyether macromonomer. [0004] The star-shaped carboxylic acid superplast...

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Problems solved by technology

[0006] For example, Shou Chongqi et al. (2011) synthesized N-hydroxyethyl-3-amino-N,N-propionic acid methyl ester, then introduced bromine-containing terminal groups through transesterification, and finally initiated atom transfer radical polymerization , to obtain a four-arm polycarboxylate superplasticizer, but its disadvantages are also obvious. The non-conjugated bromine-containing end group obtained by transesterification has a low activity of the central initiator to initiate polymerization, resulting in a polymerization process in the The central molecule initiates less, and the thermally induced self-polymerization occupies a certain amount, which cannot give full play to the steric hindrance advantages provided by the star initiator.

[0007] Pei Jikai et al. (2018) used double metal cyanide complexes to catalyze the polymerization of ethylene oxide to obtain high-molecular-weight isobutylene-based polyoxyethylene ether, and then copolymerized with acrylic acid to obtain star-shaped side chains. The polymerization method used is still traditional Free radical copolymerization, it is difficult to design the structure of the polymer, and the reactivity ratio still exists

[0008] Chinese patent ZL 201610122451.1 discloses a preparation method of star-shaped polycarboxylic acid-based water reducer, using polyols to carry out esterification reactions with carboxyl-containing trithioesters, dithioacids, etc. The central compound of the transfer group is then copolymerized with unsaturated acid and polyether to obtain a polycarboxylate water reducer with controllable structure, but due to the excessive amount of alkyl groups such as trithioester used in the preparation, the hydrophobicity Strong, low solubility in water, difficult to regulate chain transfer

[0009] Chinese patent ZL 201610122454.5 discloses a preparation method of a star-shaped polycarboxylate water reducer with controllable molecular structure. A compound with a multi-halogen end group, and then initiates atom transfer radical polymerization on it, and sodium methacryl sulfonate, allyl polyoxyethylene ether, allyl sodium sulfonate, vinylbenzene sulfonate, methyl Sodium allyl sulfonate, sodium methoxyallyl sulfonate, potassium allyl sulfonate, potassium styrene sulfonate, potassium vinyl sulfonate, potassium methallyl sulfonate, methallyl Potassium oxysulfonate, etc. are copolymerized into copolymers, but limited to the solubility of different monomers and initiators, and the complexation of groups on the polymer to metal ions, the molecular structure can be regulated, but the synthesized star Type polycarboxylate superplasticizer has the advantages of low dosage, high water reducing rate, small slump and good cement compatibility.

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