羧甲基-β-环糊精减水剂的制备与性能

Preparation and Properties of Carboxymethyl-β-cyclodextrin as A Water-reducer

以β-环糊精和氯乙酸为原料,通过亲核取代反应制备了混凝土减水剂羧甲基-β-环糊精(CM-β-CD),讨论了反应物物质的量比、反应温度和反应时间对CM-β-CD的取代度及应用性能的影响。结果表明,当氯乙酸与β-环糊精物质的量比为6∶1、反应温度为60℃、反应时间为5h时,所得CM-β-CD的取代度最大为0.68。水泥净浆实验表明净浆流动度随着取代度的增加而增加,减水剂的最佳掺量为0.8%,减水率为23.5%。红外光谱(FTIR)和核磁共振光谱(NMR)检测结果表明β-环糊精和氯乙酸发生了反应。

The concrete water-reducer of carboxymethyl-β-eyclodextrin（CM-β-CD） was prepared by nucleophilic substitution reaction of monochloroacetic acid（C1CH2 C（X）H） and β-CD under the condition of alkaline. Effects of molar ratio of β-CD and monochloroacetic acid, reaction temperature and time on the degree of substitution（DS） and the application properties were investigated. The results show that the maximum DS of 0. 68 can be obtained when n（ClCH2COOH） ： n（β-CD） is 6 ： 1 at 60℃ for 5h. The fluidity of cement pastes increased with increasing DS and the water reducing ratio was 23. 5% under the dosage of water-reducer was 0. 8%. Meanwhile, FTIR and NMR results indicated that monochloroacetic acid was grated on the structure of β-CD successfully.