Reaction conditions, characterization, dispersion properties of an eco-friendly aminosulfonate-bisphenol A-formaldehyde superplasticizer

Superplasticizers (SPs) are an indispensable ingredient to prepare high performance concrete. In the present work, sodium sulfanilate (ASAA), bisphenol A (B) and formaldehyde (F) were used as the reactive monomers, the sustainable aminosulfonate-bisphenol A-formaldehyde (ASBF) SP was synthesized. The functional groups, the weight-average molecular weight (M_w), the number-average molecular weight (M_n), the sulfonation degree (SD), the dispersion properties of ASBF SP were examined. The relationships between the reaction conditions and the molecular structures, the dispersing behaviors of ASBF SP were built. The optimum reaction conditions of ASBF SP are that the molar ratios of B/ASAA, F/(ASAA + B) are 0.625, 1.2, pH value, reaction temperature and reaction time were kept at 10.8, 90–95 °C, 4 h. The molecule of ASBF SP prepared under the optimum reaction conditions has -NH₂, -OH, -C₆H₅, -SO₃ groups and M_w, M_n, PDI, SD for 24,716 Da, 16,855 Da, 1.466, 2.257 mmol/g. The adsorption of ASBF SP provides an electrostatic repulsion force to disperse cement particle. -SO₃ group on the molecule of ASBF SP takes place complex reaction with calcium ion on cement. The combined affects cause that ASBF SP has the better dispersing capacity for cement particle and dispersing retention in cement slurry.