Abstract: Hollow calcium carbonate(CaCO₃) microspheres with different morphologies were synthesized via the precipitation reaction of calcium chloride with sodium carbonate in the presence of different surfactant-polymer complexes. The selected anionic surfactants were sodium dodecyl sulfonate(SDS) and sodium dodecyl benzenesulfonate(SDBS), respectively. The selected water-soluble polymers were polyacrylic acid(PAA) and polyvinyl pyrrolidone(PVP). In this work, SDS-PVP “pearl-necklace model” micellar complex was formed via hydrophobic effectiveness between SDS and PVP and it served as the spherical template to generate spherical CaCO₃ aggregates with hollow microspheres composed of about 500 nm irregular shaped particles. SDS-PAA complexes and SDBS-PAA complexes formed “core-shell model” aggregates with calcium ions serving as the medium to link the anionic surfactant and the polymer. SDS-PAA “core-shell model” aggregates would act as templates for hollow CaCO₃ microspheres consisting of 30-50 nm irregular shaped crystallites. SDBS-PAA “core-shell model” aggregates served as the spherical aggregate templates to generate spherical CaCO₃ aggregates consisted of many small spherical particles which had grown together. All the obtained CaCO₃ hollow microspheres are calcite particles. This research may provide new insight into the control of morphologies of hollow CaCO₃ microspheres in the presence of surfactant- polymer complexes.

Key words: Surfactant-polymer complex, Calcium carbonate, Hollow microsphere