Regulation of different functional groups on inorganic phase of calcium carbonate crystal

Several typical functional groups, —OH, —NH₂, —COOH and —CH₃ were selected in this work. In order to study the effect of the functional groups on calcium carbonate mineralization, the groups were grafted on single crystal silicon chips. The modified chips were used as substrates in the in vitro mineralization experiments. The contact angle was measured to examine the grafting efficiency, and the results showed that the groups were all successfully grafted. Raman was used to determine the crystal form. SEM was used to observe the morphology, size, quantity and orientation of calcium carbonate crystals. The results show that on -OH modified substrate, calcite aggregates are found, on —NH₂ and —COOH modified substrates, some vaterites are found with different morphologies, on —CH₃ modified substrate, less crystals are found compared with the blank. It is supposed that —OH and —CH₃ have no significant control effect over the polymorph of calcium carbonate crystals, —NH₂ and —COOH can induce vaterite crystal growth by absorbing CO₃^2- or Ca²⁺.