聚羧酸系高效减水剂的合成及其作用机理研究

Research on Synthesis of Molecular Structure Design of Polycarboxylate Superplasticizer

分析了聚羧酸系高效减水剂的结构与性能之间的关系,探讨了减水剂分子的主链结构单元与支链结构单元的功能与作用,并分类介绍了聚羧酸系的分子结构设计及其合成的研究与进展。结果表明,聚羧酸系减水剂的性能与其分子结构的主链和支链的结构单元、官能团的位置及其种类有关。在分子主链上引入大量合适大小分子量的聚乙二醇或聚氧乙烯接枝链和少量它们的嵌段链及一定构成比例的磺酸基团,可使减水剂在发挥低掺量高分散性的同时,产生良好的保塑性,且在合成过程中发现,聚氧烷基中的端羟基易引起凝胶。在此基础上结合原料的来源及其成本,选用聚乙二醇与丙烯酸在对甲苯磺酸作催化剂的条件下进行酯化,然后与甲基丙烯磺酸钠进行共聚,并加入一定量的丙烯酸单体来调节主链的大小及侧链上的羧基与磺酸基的相对构成比例,从而得到一种高性能减水剂。

The relationship between the structure and the performance of polycarboxylate superplasticizer was analyzed. The respective function of the structure unit of principal and branched chain was discussed. And the progress of synthesis and molecular structure design of polycarboxylate superplasticizer was reviewed according to the difference in the structure unit of principal chain. The results indicated that their performance related to the structure unit of principal chains and branched chains, the position and species of functional groups, the position and species of functional groups. The polycarboxylate superplasticizer, which had suitable graft and block polymers of polyethylene glycol or polyoxyethylene, and suitable of sulfonic group, had small slump loss besides high water-reducing performance. On the another hand, hydroxyl group in the end of the chain caused gellation easily. On the basis of the mentioned above, the source and cost of raw materials, esterification of polyethylene glycol and acryl acid were firstly adopted by using the catalyst of para-toluenesilfonic acid as catalysis, then polymeriation with sodium methylsulfonate. Acryl acid was added in order to regulate the polymerization degree of the principal chain, and the ration of carboxy and sulfonic groups in the branched chain. As a result, the high performance superplasticizer was synthesized.