Polycarboxylate superplasticizer (PCE) is a common admixture in high performance concrete. In the design of PCE molecules, it is necessary to ensure that the molecular weight of the polymer is moderate and the acid‐ether ratio is appropriate to improve the dispersion effect. Chain transfer agent is usually added in the synthesis of PCE to adjust the molecular weight and distribution of PCE. In this study, three sulfhydryl chain transfer agents with different electron‐withdrawing groups or electron‐donating groups were synthesized by nucleophilic addition reaction based on sodium hydrosulfide method. Then, three kinds of PCE containing sulfhydryl chain transfer agent were prepared and compared with commercial β‐mercaptopropionic acid superplasticizers. The yield stress and plastic viscosity of cement paste samples prepared by PCE−A and PCE−M were close to those prepared by PCE−P. PCE−M and PCE−A prepared by chain transfer agent with electron‐withdrawing group had higher dispersion and retention capacity than PCE−P, and had more obvious delay of cement hydration and lower hydration accumulated heat. Therefore, the optimization of molecular structure of chain transfer agent is helpful to improve the properties of concrete superplasticizer.

中文翻译：

---

不同结构链转移剂聚羧酸减水剂的制备及性能

聚羧酸减水剂（PCE）是高性能混凝土中的常见外加剂。在PCE分子设计中，需要保证聚合物的分子量适中，酸醚比合适，以提高分散效果。 PCE合成中通常添加链转移剂来调节PCE的分子量和分布。本研究基于硫氢化钠法，通过亲核加成反应合成了三种具有不同吸电子基团或给电子基团的巯基链转移剂。然后，制备了三种含巯基链转移剂的PCE，并与商业β-巯基丙酸高效减水剂进行了比较。 PCE-A和PCE-M制备的水泥浆体样品的屈服应力和塑性粘度与PCE-P制备的水泥浆样品接近。具有吸电子基团的链转移剂制备的PCE-M和PCE-A比PCE-P具有更高的分散和保留能力，并且具有更明显的水泥水化延迟作用和更低的水化积热。因此，链转移剂分子结构的优化有助于提高混凝土高效减水剂的性能。