Preparation of mesogen-functionalized dendrimers for second-order nonlinear optics
2002 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 35, no 5, 1663-1671 p.Article in journal (Refereed) Published
Liquid crystalline dendrimers with peripheral mesogen-containing units have been prepared. Multistep synthesis with several selective reactions was used in the preparation of the mesogen-containing molecules, 4-[10-(hydroxycarbonyl)decyloxy]phenyl 4-[4'-(2-(R)-octyloxy)-3'-nitrophenyl]benzo ate and 4-[10-(hydroxycarbonyl)decyloxy]biphenyl 4-[4'-(2-(R)-octyloxy)-3'-nitrophenyl]benzoate. Both molecules possessed an electron-accepting nitro group placed perpendicular to the long axis of the molecules in order to enhance the nonlinear optical activity. A second generation hydroxyl functional aliphatic dendrimer based on the dihydroxy acid, 2,2-bis(hydroxymethyl)propionic acid, was used as dendritic scaffold and was subsequently functionalized with the aforementioned groups. The purity and structure of the two liquid crystalline dendrimers were determined by H-1 NMR spectroscopy, size exclusion chromatography, and elemental analysis. The synthesis of both the mesogen-containing units and the liquid crystalline dendrimers is described in detail. Investigation of the liquid crystalline properties of the materials by differential scanning calorimetry and optical microscopy showed that they exhibited different mesophases, including the chiral smectic C phase. Ferroelectric switching was observed in this tilted phase, and electrooptical properties, including tilt angle and spontaneous polarization measurements, were investigated. Finally, the nonlinear optical properties of one of the materials were preliminary characterized.
Place, publisher, year, edition, pages
2002. Vol. 35, no 5, 1663-1671 p.
ferroelectric liquid-crystals, 2nd-harmonic generation, spontaneous polarization, polymer plcp, design, polar, polysiloxanes, polyesters
IdentifiersURN: urn:nbn:se:kth:diva-21345DOI: 10.1021/ma010290jISI: 000174036600029OAI: oai:DiVA.org:kth-21345DiVA: diva2:340043
QC 201005252010-08-102010-08-10Bibliographically approved