Novel concrete superplasticizers containing crown ether pendant side chains for improved cement paste workability

In this work, new concrete superplasticizers based on crown ethers as the bulky pendant side chains have been prepared. First, reversible addition-fragmentation chain transfer (RAFT) polymerization of methacrylic acid (MAA) and pentafluorophenyl methacrylate (PFPMA) was performed to prepare poly(MAA-co-PFPMA) as a precursor. A subsequent transesterification reaction with hydroxymethyl-crown ethers (CR) was performed to prepare poly(MAA-co-CR) superplasticizers with different crown ether side chains, namely 12-crown-4 (12CR4), 15-crown-5 (15CR5), and 18-crown-6 (16CR6). The prepared copolymers were characterized using nuclear magnetic resonance (NMR) spectroscopy and size exclusion chromatography (SEC) to confirm their structure and elucidate their molecular weights, respectively. Rheological studies and fluidity measurements revealed that the ring size of crown ether plays a crucial role in enhancing the dispersion and workability retention of cement pastes. It has been found that a moderate ring size can result in the highest cement flowability and workability retention performance, and thus polymers with this pendant group could be of potential interest in the concrete industry as novel superplasticizers containing new pendant groups.

Automated summary

In this work, new concrete superplasticizers based on crown ethers as pendant side chains have been prepared. The copolymers with different crown ether side chains showed enhanced dispersion and workability retention in cement pastes. The findings suggest that polymers with a moderate ring size can be of interest as novel superplasticizers in the concrete industry.