Synthesis and Properties of a Polycarboxylate Superplasticizer with a Jellyfish-Like Structure Comprising Hyperbranched Polyglycerols

Polycarboxylate superplasticizers (PCEs) are comb-shaped polymers with an anionic backbone and several nonionic pendant chains, which typically are comprised of polyethylene glycols. In this study, the synthesis of a new type of superplasticizer is presented, which does not exhibit the typical comb-shaped form of PCEs but is built up from a linear polyetheramine and a hyperbranched polyglycerol scaffold, which was carboxymethylated in the periphery. H-1/C-13 NMR and FT-IR spectroscopy and size exclusion chromatography were employed for the characterization of the polymers. Furthermore, their dispersing performance and slump retention capability were investigated in cement pastes. Adsorption and zeta potential measurements as well as heat flow calorimetry were conducted to gain more insight into the interaction of the polymers with cement. It was found that such non-comb-shaped polymers are highly effective cement dispersants. Moreover, the hyperbranched superplasticizers exhibited high robustness toward alkali sulfates and maintained the fluidity much longer, compared to a conventional comb-shaped PCE.