Amphiphilic templating of magnesium hydroxide.
The synthesis of lamellar mesostructured Mg(OH)2 was achieved through a surfactant templating route. Amphiphilic compounds with different anionic headgroups (phosphate, sulfate, sulfonate, and carboxylate) were used as surfactants. Control of d spacing was achieved through the use of different alkyl carboxylate amphiphiles. It is proposed that the interaction between the highly reactive oxygen atoms of the anionic surfactants and the highly electrophilic Mg atom leads to the formation of high charge density at the interface between the surfactant molecules and the inorganic precursor. This interaction is very strong and the existence of strong bonds between the headgroup molecules of the surfactant and the Mg atom locks the structure in a preferred orientation, i.e., lamellar mesostructure. The strong interaction thus precludes any phase transformation, and only the lamellar phase of Mg(OH)2 is obtained. Calcination of the surfactant by heating in oxygen flow leads to the collapse of the lamellar mesophase and results in the formation of nonporous MgO.
Ranjit
Koodali T
KT
Department of Chemistry, University of South Dakota, Vermillion, South Dakota 57069, USA. rkoodali@usd.edu
Klabunde
Kenneth J
KJ