Research Of Synthesis And Water Reducing Performance Of Hyperbranched Polymer

A Hyperbranched polymer(HBP) is a class of highly branched macromolecules spherical structure, which contains a large active, surface functional group; each functional group can be further functionalized. When the polycarboxylate superplasticizer was modified by hyperbranched polymer with multi-branched chain structure, the HBP has many special properties of hyper-branched. The macro molecular structure of HBP increases the contact area and bonding force between superplasticizer and cement particles, and the steric repulsion of superplasticizer was greatly increased either. Cement particles with better dispersion were harder to get together. HPC was a breakthrough to the existing structure of superplasticizer.Firstly, in this paper, macro monomer A and B were synthesized by diethanolamine and diallylamine respectively reacted with diallylamine through Michael addition reaction. Different generation terminal hydroxyl HBP superplasticizer was obtained by trimethylol propane and the monomer A through the transesterification reaction. The first generation terminal double bond intermediate substance was obtained by monomer B and tri-methylol propane. The second generation,、and third generation terminal double bond polymer were obtained by the first generation and second generation hydroxyl-terminated hyper-branched polymers reacted with monomer B.Azoisisobutyronitrile(AIBN) as catalyst, the carboxyl is introduced into the terminal double bond intermediate substance by intermediates and thioglycolic acid through the Michael addition reaction, terminal carboxyl HBP superplasticizer was successfully obtained.Monomers A, Band two different terminal groups HBP were characterized by FTIR were characterized by FTIR spectra, NMR spectroscopy. The dispersion properties of the two different terminal groups HBP was further evaluated by Paste fluidity test and water rate and mechanical properties test of the mortar. The Adsorption, surface tension and zeta potential were also tested for investigating the main mechanism for HBP in cement. The results showed the pre-designed molecular structure was successfully synthesized and the two types HBP have excellent dispersion effect. The steric repulsion between the cement particles carrying adsorbed polymer molecules is the main mechanism for dispersion. But terminal carboxyl HBP superplasticizer also relies on a certain degree of electrostatic repulsion to improve the dispersion of cement particles effect.In summary, both the two different terminal groups HBP have a certain fluidity retention and absorption and can reduce the surface tension. Especially terminal carboxyl HBP superplasticizer is worth further research and discussion, in order to achieve a wide range of application.