A hybrid double-hydrophilic block copolymer (DHBC) of PEG-b-PEI-SO3H with sulfonic groups was synthesized and investigated as a modifying additive for CaCO3 crystallization.The DHBC was well characterized by FTIR.Primary investigations indicated that this hybrid double hydrophilic block copolymer (DHBC) possessed strong modifying ability for both polymorphism and morphologies of inorganic crystals due to the especial structure with sulfonic groups.The crystal morphologies were investigated by SEM and TEM.The SEM and TEM results indicated that pure hollow round ring calcite was obtained after 1 day

while mussel-like and sphericallike calcium carbonates were produced after 3 or 5 days.When the reaction time was 7 days

almost pure spherical particles were obtained.The crystal phases were fully characterized with FTIR

XRD.The XRD results indicated that the calcium carbonate obtained after 1 day was calcite

and not only calcite but also vaterite was formed after 3 or 5 days

pure vaterite was produced after 7 days.These results were accordant with the FTIR measurement.When the reaction time was 1 day

the peaks at 875 cm-1 and 712 cm-1 indicated the calcium carbonate obtained was calcite.With prolonging of reaction time from 1 day to 3 or 5 days

the peaks at 875 cm-1

745 cm-1 and 712 cm-1 identified the calcite as well as vaterite crystals.While the 875 cm-1 and 745 cm-1 peaks appeared after 7 days

but the peak at 712 cm-1disappeared

which showed that the pure vaterite was produced.