|
| << vorige | volgende >> |
Tijdschrift beschrijving
Alle jaargangen van het bijbehorende tijdschrift
Alle afleveringen van het bijbehorende jaargang
Alle artikelen van de bijbehorende aflevering
Details van artikel 98 van 131 gevonden artikelen
| Titel: |
Synthesis and characterization of side-chain liquid-crystalline poly(ethyleneimine)s with cyanobiphenyl groups |
| Auteur: |
Xie, Minli Zhang, Chaocan |
| Verschenen in: |
Liquid crystals |
| Paginering: | Jaargang 34 (2007) nr. 11 pagina's 1275-1283 |
| Jaar: |
2007-11 |
| Inhoud: |
A series of polyethyleneimine-based side-chain liquid-crystalline polymers substituted with different ratios of cyanobiphenyl as pendent mesogenic groups has been synthesized in which the spacer length varies between two and six methylene units. The structures of the synthesized polymers are confirmed by infrared and 1H nuclear magnetic resonance spectroscopy. The thermal properties of these polymers have been investigated using differential scanning calorimetry, polarized optical microscopy and X-ray diffraction. The results indicate that the thermal behaviour of the polymers is strongly dependent on the degree of substitution. Polymers containing more than 69% of mesogenic groups exhibit nematic-type thermotropic liquid-crystalline behaviour with schlieren textures. Below this limit, the polymers are amorphous. Polymers with a higher degree of substitution present the crystalline states. The phase transition temperatures increase and the mesomorphic temperature ranges widen with increasing degree of substitution. The clearing temperatures decrease as the spacer length increases. An odd-even effect in the clearing temperatures is observed and the odd members display the higher values. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 98 van 131 gevonden artikelen
| << vorige | volgende >> |