Control over calcium carbonate phase formation by dendrimer/surfactant templates.
Poly(propylene imine) dendrimers that are modified with long alkyl chains self-assemble to form well-defined aggregates. The geometry and surface chemistry of the dendrimer assemblies can be varied through the addition of surfactants. These dendrimer/surfactant aggregates can be tuned to template the formation of the different phases of calcium carbonate. The use of octadecylamine results in the formation of polyhedral aggregates that become embedded within an amorphous calcium carbonate phase that persists in competition with the thermodynamic product, calcite. In combination with hexadecyltrimethylammonium bromide, small spherical aggregates are formed that induce the formation of vaterite. The use of the negatively charged surfactant SDS results in growth retardation by the Ca(2+)-induced agglomeration of dendrimer/surfactant aggregates into giant spherical particles. Eventually these particles become overgrown by rhombohedral calcite.
Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Jack J J M
JJ
Donners
Brigid R
BR
Heywood
E W
EW
Meijer
Roeland J M
RJ
Nolte
Nico A J M
NA
Sommerdijk
D002119:Calcium Carbonate / Q000737:chemistry*; D003460:Crystallization; D019281:Dimerization; D008854:Microscopy, Electron; D010316:Particle Size; D011126:Polypropylenes / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*
D011126:Polypropylenes; D013501:Surface-Active Agents; C443641:poly(propyleneimine); D002119:Calcium Carbonate