Enhanced adsorption and properties of TPEG-type superplasticizers modified by maleic anhydride: a perspective from molecular architecture and conformation

A series of polycarboxylate superplasticizers (PCEs) with varying carboxyl densities were synthesized at room temperature using the molecular design principle. The PCEs molecular structure was determined using 1 H NMR and MALDI-TOF. The paste fluidity, foam stability as well as other performance of PCEs obtained was also tested. The investigations reveal that the PCEs with high carboxyl density cause the extended main chain conformation due to the strong electrostatic repulsion, resulting in the increase of hydrodynamic radius (Rh), which is beneficial to increase the ‘accessible carboxyl’ in the main chain, and improves its adsorption capacity; In addition, the PCEs with high carboxyl density also have high hydrophilicity, which will form micro bubbles to better disperse cement particles, and improve the fluidity of cement pastes. This study is aimed to provide a comprehensive understand for the mechanism of maleic anhydride-modified TPEG-type PCEs from the viewpoint of molecular architecture and conformation, and improve the workable performance of concrete mixture with the PCEs.