Synthesis and control of nanostructure using supramolecular self-assembly

Abstract

We describe the rational design, synthesis and characterization of the supramolecular amphiphilies as building blocks obtained by the esterification of the monodendrons, Methyl 3,4,5-Tris[4-(4’-(n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-Heptadecafluorododecan-1-yloxy)phenyl)benzyloxy]benzoate (F8PB, 5) and 3,5-Bis[3’,5’-bis(n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-Heptadecafluorododecan-1-lo- xy)benzyloxy]benzoic acid (F8B, 10), containing semifluorinated dodecyl tails and a dramatic development of orientation in supramolecular cylinders by an applied magnetic field. Two supramolecules of all synthesized molecules, F8PB and F8B, self-assemble into supramolecular architectures that self-organize into hexagonal columnar liquid crystalline phase. Equilibrium phase transitions of the materials are identified by differential scanning calorimetry (DSC), polarized light microscopy (PLM) and synchrotron X-ray diffraction. The direct structural images were obtained using transmission electron microscopy (TEM). The fluorination of the dodecyl groups of these tapered building blocks enhances dramatically their self-assembly and thermal ability. The self-assembling ability of the materials is enhanced by process via microsegregation of the perfluorinated and perhydrogenated parts due to the fluorophobic effect. The fluorinated tails, rigid rods such as biphenyl segment and functional groups that generated hydrogen-bonding cause the molecules to self-organize into highly stable hexagonal columnar LC phase. The response of the supramolecules to external magnetic fields has been investigated by small-angle neutron scattering (SANS) and TEM. The SANS data of the supramolecules with aromatic moiety reveal a perpendicular orientation of the columnar directors with respect to applied magnetic fields under an applied field of 1.00-T when the samples are cooled from their isotropic phases. We account for these observations on the basis of the competing diamagnetic moments of the mater...