Method for synthesizing cationic polycarboxylate superplasticizer based on Hoffmann rearrangement reaction

Abstract

The invention discloses a method for synthesizing a cationic polycarboxylate superplasticizer based on a Hoffmann rearrangement reaction, and belongs to the field of water reducing agents. Unsaturated amide monomers are modified into unsaturated isocyanate, meanwhile, an oxidation-reduction initiating system is formed by high-valence cerate and alcohol to initiate polymeric unsaturated cation quaternary ammonium salt monomers, a hydroxyl-terminated cation side chain is obtained, then isocyanate reacts with the hydroxyl-terminated cation side chain and polyethylene glycol monomethyl ether to obtain cationic macromonomers and polyether macromonomers, then the cationic macromonomers, the polyether macromonomers and small carboxylic acid monomers are subjected to free radical copolymerization, and the cationic polycarboxylate superplasticizer is obtained. Based on the Hoffmann rearrangement reaction principle, unsaturated amide modified amide reacts with the cation side chain and a polyether side chain, the macromonomers with different structures and different functions are designed and synthesized, and the novel pectinated polycarboxylate superplasticizer with polycarboxylic acid as a main chain and cations and polyether as the side chain is obtained finally. The synthesis process is continuous and easy to control, and multiple effects of excellent water reduction, collapse protection, clay resistance and the like are shown.

Description

technical field [0001] The present invention relates to the technical field of a cationic side chain type polycarboxylate water reducer for concrete, in particular to a cationic side chain polymerized by Hoffman rearrangement reaction of unsaturated amide monomers first to modify isocyanate groups And react to generate a macromonomer and then copolymerize with a small carboxylic acid monomer to form a specific preparation method of a cationic polycarboxylate water reducer. Background technique [0002] Polycarboxylate superplasticizer is an important part of concrete, which can improve the workability, strength and durability of concrete. It is a high-performance superplasticizer at the forefront of technology in the world. The characteristics of high water-reducing enhancement rate, good adaptability of cement, and diversity of molecular design have become the research hotspots at home and abroad. However, concrete raw materials have an important impact on the application ...

AI Technical Summary

Problems solved by technology

However, the products obtained by the above synthetic methods all have certain deficiencies. In the field of concrete water reducers, researchers have failed to modify the isocyanate through the amide structure and initiate the polymerization of cationic side chains and polymers in the system with high-valent cerium salts. The method of separately reacting the ether side chains to obtain two kinds of macromonomers realizes the composite functional polycarboxylate superplasticizer integrating water reduction, slump retention, dispersion, mud resistance and other application properties.

The method of modifying isocyanate only through Hoffman rearrangement reaction, or synthesizing a single functional side chain, or introducing a cationic block into the main chain greatly limits its application effect in concrete. It has been proved by facts that the synthesis of complex functional group molecules with multiple functions The structure can significantly improve the application performance of the polymer

Therefore, this requires a fundamental innovation in the molecular structure of the synthesized polycarboxylate superplasticizer. It does not stick to the traditional synthesis method, and innovatively uses amide-modified isocyanate, high-valent cerium salt to initiate long chain polycations, and isocyanate. Reaction with polycation side chains and polyether side chains to obtain a variety of synthetic routes and characteristics of macromonomers, which not only has the composite performance of water-reducing and slump-resistant mud, but also facilitates industrial application and production promotion. Regarding this aspect The work has not been reported at home and abroad

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