Functionalized Multiwalled CNTs in Classical and Nonclassical CaCO₃ Crystallization

Area of Science:

• Materials Science
• Nanotechnology
• Crystallography

Background:

• Multiwalled carbon nanotubes (MWCNTs) are advanced nanomaterials with diverse applications.
• Controlling calcium carbonate (CaCO3) crystallization is crucial in various scientific and industrial fields.
• Understanding inorganic mineralization processes requires precise control over nucleation and crystal formation.

Purpose of the Study:

• To investigate the efficacy of oxidized and functionalized MWCNTs as additives for controlling CaCO3 nucleation.
• To synthesize and stabilize amorphous calcium carbonate (ACC) proto-structures using MWCNTs.
• To explore the potential of MWCNTs in creating fluorescent hybrid CaCO3 materials.

Main Methods:

• Gas diffusion (GD) method was employed for CaCO3 crystallization.
• MWCNTs were oxidized and functionalized with itaconic acid and monomethylitaconate.
• Prenucleation cluster (PNC) intermediates were utilized for ACC synthesis.
• Fluorescein-5-thiosemicarbazide (5-FTSC) dye labeling was used to create fluorescent hybrids.

Main Results:

• Functionalized MWCNTs effectively controlled CaCO3 nucleation, yielding aragonite and truncated calcite.
• For the first time, all amorphous calcium carbonate (ACC) proto-structures (proto calcite-ACC, proto vaterite-ACC, proto aragonite-ACC) were synthesized and stabilized at room temperature.
• MWCNTs exhibited concentration-dependent nucleation promotion and inhibition effects.
• Fluorescent hybrid nanosized CaCO3 was successfully synthesized by incorporating 5-FTSC dye-labeled MWCNTs.

Conclusions:

• Functionalized MWCNTs serve as efficient additives for controlled selective crystallization of CaCO3.
• This study provides new insights into inorganic mineralization processes via PNC intermediates.
• MWCNTs offer a promising alternative for developing novel functional nanomaterials and hybrid structures.