The influence of molecular sequence structure of polycarboxylate ether slump retaining agent on its performance
Two polycarboxylate ether(PCE)slump retaining agents of PCE-1/PCE-2 with a random sequence structure were syn-thesized by conventional free radical polymerization in this article,which had different side chain density distributions.PCE-3/PCE-4 with gradient sequence structure were synthesized by reversible addition-fragmentation chain transfer polymerization(RAFT),and their side chain distribution forms are"outer dense inner sparse"and"outer sparse inner dense",respectively.The gel permeation chro-matography(GPC)test showed that the molecular weight of PCE-3/PCE-4 increased linearly with the conversion rate,which conformed to the"living"polymerization characteristics.Through cement paste and concrete tests,it was found that their dispersion performance was ranked as PCE-4＜PCE-1＜PCE-2＜PCE-3,indicating that the sequence structure of"outer dense and inner sparse"is most suit-able for exerting the dispersion ability of PCE,while"outer sparse and inner dense"is not suitable as the structure of PCE.The montmorillonite-contained cement paste test showed that PCE molecules with a"tight"side chain sequence(PCE-1/PCE-3)have better clay resistance.The adsorption test results indicate that their adsorption capacity is ranked as PCE-4＜PCE-3＜PCE-1≈PCE-2.
polycarboxylatereversible addition-fragmentation chain transfer polymerizationgradientdispersion performance
万方数据
维普
