Synthesis of high concentration polycarboxylate superplasticizers via a photoinitiated one-pot method

Abstract

Polycarboxylate superplasticizers (PCEs) are primarily liquid products (40 wt%) with narrow application range, which incur high transportation and storage costs. However, the high reaction viscosity makes it challenging to produce high concentration PCEs. In our study, high concentration PCEs are successfully synthesized by a photoinitiated one-pot method at room temperature. The results show that the reaction viscosity of photoinitiation is slightly higher than that of traditional initiation systems, but the photoinitiated reaction remains stable and controllable, with no occurrence of violent polymerization. The impact of varying reaction concentrations on the polymerization rate, molecular structure, and properties of PCEs has been studied under the photoinitiated one-pot method. The results indicate that an increase in reaction concentration leads to a rise in polymerization rate, molecular weight, and molecular gyration radius of the polymers. The conversion rate of the macromonomer exceeds 80%, while the polydispersion index (PDI) for molecular weight is below 2 with a narrow distribution. Furthermore, the monomer polymerization ratio of the product remains close to the feeding ratio at different reaction concentrations. Finally, it is observed that PCEs with a high concentration of 80 wt% exhibit favorable dispersion, rheology and adsorption properties. This study presents a new method for synthesizing high concentration PCEs using photoinitiation.