Synthesis of side‐chain liquid‐crystalline polysalts with a poly(methylsiloxane) backbone

Abstract

The synthesis and thermal properties of side-chain liquid-crystalline polysiloxanes, incorporating quaternized pyridyl groups, are described. The polymers are obtained by hydrosilylation of poly(hydrogenmethylsi1oxane) with a protected alcohol. Reaction of the deprotected polysiloxanes with 4-(hydroxymethyl)pyridine and subsequent reaction with mesogenic alkyl bromides of different structure yielded the desired poly[(6-[ N-[w-(4'-alkoxy-4-biphenylyloxy)alkyl]-4-pyridiniomethoxy ) hexy1)methylsiloxane bromide]. Four different types of polymers are prepared with either octyl or dodecyl alkyl chain, and with either methoxy or S-2-methyl-1-butoxy as an alkoxy group. Degrees of quaternization up to 80% are obtained. First results of their liquid-crystalline behaviour investigated by optical polarizing microscopy and differential scanning calorimetry are reported.

Thermotropic liquid crystalline behaviour of pyridinium and poly(4-vinylpyridinium) salts quaternized withω-alkyl phenylbenzoate derivatives

“…In these materials, smectic phases were observed in which the mesogenic pendant groups (4-alkoxybiphenyl-49-yloxy type) were arranged in single layers, with the polymer backbone bearing ionic groups inserted between the layers. In the particular case where ionic groups have been incorporated into the spacer 4) , smectic phases were also observed with the same type of mesogenic group. These results demonstrate the highly smectogenic function of the ionic units located in the backbone or in the spacer and the predominant rôle of the electrostatic interactions in the establishment of smectic order.…”

Ionic Liquid Crystals: Versatile Materials

“…Although this temperature is still well above the clearing point of 299-crown-b and thus does not affect its practical applicability to a great extent, the proposed relatively facile thermal decomposition of the organosiloxane substituents in ionic compounds (despite the shielding of the charges in 299-crown-b ) should be kept in mind when designing future ILCs that would show a SmC phase. It should be noted that the number of reported ionic mesogens containing siloxane moieties is very limited, ,− and except for the compounds synthesized by Mizoshita and Seki ( 191 and 192 ), all of the examples encompass high molecular weight poly­(siloxane) species. Ikker et al observed slow degradation of the poly­(siloxane) backbone only above 400 °C by TGA …”

“…It should be noted that the number of reported ionic mesogens containing siloxane moieties is very limited, ,− and except for the compounds synthesized by Mizoshita and Seki ( 191 and 192 ), all of the examples encompass high molecular weight poly­(siloxane) species. Ikker et al observed slow degradation of the poly­(siloxane) backbone only above 400 °C by TGA …”

Effect of smectogenicity of the ionic groups on the thermotropic liquid crystalline behavior of pyridinium and poly(4-vinylpyridinium) salts quaternized with mesogenic groups

“…X-ray diffraction was alkyl bromides were prepared in three steps as already described. 3 First, 2-methylbutanol was reperformed on a Debye-Scherrer camera, the Xray beam (Cu Ka) being produced by a rotating acted with tosyl chloride. Then, the p-toluenesulfonate was treated with 4,4-biphenyldiol reanode from Eliott.…”