Chemical admixtures are in high demand in concrete technology to enhance their properties such as durability, flowability, setting, and mechanical performance. Among these chemical admixtures, superplasticizers (SP) are mainly used to enhance the flowability at a relatively low water-cement ratio (w/c). The first generation of superplasticizers such as sulphonated naphthalene formaldehyde condensates and amino sulphonate formaldehyde condensates can disperse cement particles via an electrostatic repulsion mechanism. The new generation of SP is based on polycarboxylate ether comb copolymers (PCE) that possess carboxylic groups and poly(ethylene oxide) side chains. PCEs have been shown to provide better performance than the older generations of superplasticizers as they create not only electrostatic repulsion but also a steric hindrance. The molecular weight and side-chain lengths of PCEs can easily be tailored, making them superior to other kinds of SPs.<br/><br/>In this work, for the first time, we have studied the effect of cyclic ethers on the performance of PCE superplasticizers. RAFT polymerization was employed for the preparation of copolymers containing activated ester side chains, i.e. copolymers of methacrylic acid (MAA) with pentafluorophenyl methacrylate (PFPMA), that were subsequently transformed to the crown ether PCEs by reaction with 2-hydroxymethyl crown ethers of different crown ether ring sizes (see Figure). The effect of crown ether size and of the respective degree of modification on water reduction and flowability of cement pastes were evaluated by rheology and using a mini-slump test. This pioneering work could contribute to the evolution of a new generation of PCE superplasticizers.

Polycarboxylate superplasticizers with cyclic ether pendant side chains

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.