Growth of CaCO3 in the templated Langmuir–Blodgett film of a bolaamphiphilic diacid

Abstract

In this paper, an organic template, the Langmuir–Blodgett (LB) film of a bolaamphiphilic diacid (1,18-octadecanedicarboxylic acid, ODA), was used to grow nanostructured calcium carbonate. ODA can form a stable Langmuir film when it is spread on the aqueous subphase containing CaCl₂. FT-IR and XPS spectra of the transferred Langmuir–Blodgett film show that formation of the stable Langmuir film is induced by Ca²⁺ ion. Through immersion of the Ca²⁺ containing LB film of ODA into aqueous Na₂CO₃ solution, nanostructured CaCO₃ can be formed in the film. Although nanoparticles were obtained at the initial times, nanorods were obtained after longer growth times. When using a LB film of the calcium salt of stearic acid, only granular particles were found. A possible mechanism is proposed to explain the formation of the nanorods in the templated LB films of these bolaamphiphiles.