CaCo3 crystallization control by poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymer and O-(hydroxy isopropyl) chitosan

Poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) ((EO)20–(PO)72–(EO)20) and O-(hydroxy isopropyl) chitosan (HPCHS) were employed as control agents of calcium carbonate crystal growth. The effect of the concentrations of polymers, [Ca2+] and [CO32−], the ratios of [Ca2+]–[CO32−] and the initial pH of the solutions were investigated. The obtained CaCO3 particles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The particles are mainly calcite with various morphologies; their size and morphologies are influenced by the polymer content. For (EO)20–(PO)72–(EO)20 systems, the initial pH has a notable influence; but in the HPCHS solution pH shows little influence. The ratio of [Ca2+]–[CO32−] clearly affects the CaCO3 particle size and aggregation degree. HPCHS showed more significant influence on CaCO3 crystallization than (EO)20–(PO)72–(EO)20. The mechanisms of the CaCO3 crystallization as controlled by (EO)20–(PO)72–(EO)20 and HPCHS are proposed and demonstrated by the molecular dynamics simulations.