Controllable synthesis of snowflake‐like α‐calcium sulfate hemihydrate microstructures using Na₂EDTA as morphology modifier

Abstract

In this work, snowflake‐like α‐CaSO4·0.5H2O (α‐CSH) hierarchical architectures were successfully synthesized by a facile one‐pot method in an ethylene glycol‐water system using Na2EDTA as a crystal morphology modifier. Characterization techniques including X‐ray diffraction (XRD), thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) confirmed the progressive morphological evolution of α‐CSH from rods to snowflake‐like structures ultimately to hexagonal plates with increased Na2EDTA concentrations. The results revealed that Na2EDTA concentration played a critical role in directing the crystallization and self‐assembly of α‐CSH, and a mechanism is proposed where Na2EDTA modulated crystal orientation through preferential adsorption and regulated the driving forces between ion‐mediated crystallization and particle‐mediated assembly. This work puts forward a simple yet effective strategy for facilely regulating the morphology of α‐CSH microstructures, which could potentially expand their applications across diverse fields such as composites, construction, biomedicine, and drug delivery.