Switchable dispersivity and molecular-trapping performance of mesostructured CaCO₃-thermosensitive polymer composite microspheres

Monodispersed thermosensitive microspheres were synthesized by the combination of poly(N-isopropylacrylamide) (PNIPAAm) and a mesostructured framework consisting of vaterite CaCO₃ nanocrystals ∼20 nm in diameter. The switchable dispersivity in water and organic media was provided to the rigid porous framework by the soft shell of the thermosensitive organic component. The microspheres were shuttlecocked between water and hydrophobic organic media by a swing in temperature across the lower critical solution temperature (LCST). The composite microspheres performed as an active carrier of organic molecules due to their switchable property. Hydrophobic molecules were captured by the microspheres dispersed in an organic medium above LCST and were then delivered and released to another organic phase through a water phase by a swing in temperature.