Hofmann, A. M. ; Wipf, R. ; Stühn, B. ; Frey, H. (2011)
Mesogen-Initiated Linear Polyglycerol Isomers: The Ordering Effect of a Single Cholesterol Unit on "Sticky" Isotropic Chains.
In: MACROMOLECULES, 44 (17)
doi: 10.1021/ma201210r
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Synthesis, thermal properties, and the liquid crystalline (LC) order of polymers consisting of a single mesogenic cholesterol unit and flexible, linear polyglycerol (PG) or poly(glyceryl glycerol) (PGG) chains have been investigated. Incorporation of the single mesogen has been achieved by using cholesterol directly as an initiator for the oxyanionic ring-opening polymerization (ROP) of ethoxyethyl glycidyl ether (EEGE) or isopropylidene glyceryl glycidyl ether (IGG). The controlled polymerization allowed the synthesis of a series of peculiar rod-oil type polyethers with molecular weights of 600-2300 g/mol, representing a degree of polymerization (DP(n) of 4-30 for both PG and PGG with the polydispersity M(w)M(n) in the range of 1.07-1.25. The resulting linear PGs exhibit extremely stable thermotropic LC order in a broad temperature range up to 260 degrees C, forming mainly layered smectic A (SmA) phases with varying layer thicknesses, depending on the degree of polymerization of the respective polymer structure. LC phases were observed up to a chain length Of 26 glycerol units, while PGGs showed no LC order. This is explained both by the steric hindrance of the branched monomer units and the higher hydrophilicity of the polymer backbone. Permethylation of the cholesterol-PG samples resulted in strongly reduced LC order or in the entire loss of the self-assembly in LC phases, which is a consequence of the disappearance of hydrogen-bonding between the functional coil segments. Detailed characterization of the phase behavior of the polymers has been achieved by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and small-angle X-ray scattering (SAXS), confirming the smectic layer structure of the materials.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2011 |
| Autor(en): | Hofmann, A. M. ; Wipf, R. ; Stühn, B. ; Frey, H. |
| Art des Eintrags: | Bibliographie |
| Titel: | Mesogen-Initiated Linear Polyglycerol Isomers: The Ordering Effect of a Single Cholesterol Unit on "Sticky" Isotropic Chains |
| Sprache: | Englisch |
| Publikationsjahr: | 13 September 2011 |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | MACROMOLECULES |
| Jahrgang/Volume einer Zeitschrift: | 44 |
| (Heft-)Nummer: | 17 |
| DOI: | 10.1021/ma201210r |
| Kurzbeschreibung (Abstract): | Synthesis, thermal properties, and the liquid crystalline (LC) order of polymers consisting of a single mesogenic cholesterol unit and flexible, linear polyglycerol (PG) or poly(glyceryl glycerol) (PGG) chains have been investigated. Incorporation of the single mesogen has been achieved by using cholesterol directly as an initiator for the oxyanionic ring-opening polymerization (ROP) of ethoxyethyl glycidyl ether (EEGE) or isopropylidene glyceryl glycidyl ether (IGG). The controlled polymerization allowed the synthesis of a series of peculiar rod-oil type polyethers with molecular weights of 600-2300 g/mol, representing a degree of polymerization (DP(n) of 4-30 for both PG and PGG with the polydispersity M(w)M(n) in the range of 1.07-1.25. The resulting linear PGs exhibit extremely stable thermotropic LC order in a broad temperature range up to 260 degrees C, forming mainly layered smectic A (SmA) phases with varying layer thicknesses, depending on the degree of polymerization of the respective polymer structure. LC phases were observed up to a chain length Of 26 glycerol units, while PGGs showed no LC order. This is explained both by the steric hindrance of the branched monomer units and the higher hydrophilicity of the polymer backbone. Permethylation of the cholesterol-PG samples resulted in strongly reduced LC order or in the entire loss of the self-assembly in LC phases, which is a consequence of the disappearance of hydrogen-bonding between the functional coil segments. Detailed characterization of the phase behavior of the polymers has been achieved by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and small-angle X-ray scattering (SAXS), confirming the smectic layer structure of the materials. |
| Fachbereich(e)/-gebiet(e): | 05 Fachbereich Physik > Institut für Festkörperphysik (2021 umbenannt in Institut für Physik Kondensierter Materie (IPKM)) > Experimentelle Physik kondensierter Materie 05 Fachbereich Physik > Institut für Festkörperphysik (2021 umbenannt in Institut für Physik Kondensierter Materie (IPKM)) 05 Fachbereich Physik |
| Hinterlegungsdatum: | 30 Jan 2012 14:00 |
| Letzte Änderung: | 05 Mär 2013 09:58 |
| PPN: | |
| Export: | |
| Suche nach Titel in: | TUfind oder in Google |
 |
Frage zum Eintrag |
Optionen (nur für Redakteure)
 |
Redaktionelle Details anzeigen |
Drucken
Impressum