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

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.