Nanoparticle-induced packing transition in mesostructured block dendron-silica hybrids

Silica type nanostructured hybrid materials have been prepared by co-assembly of sol-gel materials and an extended amphiphilic dendron consisting of a hydrophilic aliphatic polyether block and hydrophobic docosyl chains. As confirmed by small- and wide-angle X-ray scattering (SAXS and WAXS) experiments, the hybrid preparation method employing simple solvent evaporation resulted in macroscopically oriented lamellar structures in which the docosyl groups crystallize normal to the lamellar plane. Contrary to a bilayer lamellar crystalline structure in the parent extended dendron, the hybrids show lamellar crystalline morphologies with an interdigitated monolayer packing of hydrophobic docosyl groups. This unusual structural transformation upon adding sol nanoparticles can be explained by alleviating an interfacial steric barrier for hydrophilic linear polyethers.