Search results for "Pendant group"

1987

X-ray measurements of stretched crosslinked liquid-crystalline side group polymers show that two types of orientation of the mesogenic groups relative to the polymer chains (parallel or perpendicular) are possible, depending on the structure of the polymer chain. For two liquid-crystalline polymethacrylates with long spacer groups (6 methylene units) the mesogenic groups orient preferably perpendicularly to the polymer chains (axis of strain). For three liquid-crystalline polyacrylates with long or short spacer groups (6 or 2 methylene units), the mesogenic groups orient preferably parallel to the polymer chains (axis of strain). The reason for this difference is not yet clear. These result…

1992

The synthesis and the results of the structural study of two copolysiloxanes with laterally fixed trinitrofluorenone (TNF) units is reported. The two copolysiloxanes having 2,4 (1a) and 5,3 (1b) dimethylsiloxane comonomer units per TNF side group differ significantly in their phase behaviour as evident from optical microscopy, differential scanning calorimetry and X-ray scattering: 1b shows a nematic mesophase whereas 1a is an amorphous material. The different phase behaviour is discussed in terms of microphase separation between the siloxane backbone and TNF side groups.

Optical and electrical properties of oriented thin films of oligomer containing betaine-type moiety in side chain

2005

Non-linear optical and electrical properties of polymer films obtained by dipole orientation of active units are reported. Novel polar oligomer with N-(indan-1,3-dion-2-yl)pyridinium betaine (IPB) as a side group is studied. Orientation of polar groups in oligomer thin films causes an increase of the photo-induced change of surface potential on irradiation in the region of photo-induced electron transfer (PIET) where the IPB group exhibits a reversible change of the value and sign of the dipole moment. At longer wavelengths, the value of the surface potential of the oligomer may be determined by transport of photogenerated charge carriers.