X. Kong, B. Tang
Oct 20, 1998
Citations
0
Influential Citations
56
Citations
Journal
Chemistry of Materials
Abstract
The synthesis of side-chain liquid crystalline polyacetylenes containing phenyl benzoate mesogens with octyl spacers and cyano (2a) or methoxy tails (2b) is accomplished, and the tuning of the molecular alignments of 2b is realized by simple mechanical perturbations. The acetylene monomers, 10-[4-(4‘-R-phenoxycarbonyl)phenoxycarbonyl]-1-decynes [R = cyano (1a), methoxy (1b)], are prepared by two consecutive esterification reactions of 10-undecynoic acid. None of the two monomers are liquid crystalline, but 1a exhibits an unusual crystal−crystal transition at 70.5 °C, probably due to its strong intermolecular ⋮C−H···N⋮C− hydrogen bonding. The polymerizations of 1 initiated by the WCl6−Ph4Sn/dioxane complex yield yellow powdery polymers (2) with Mw of ca. 30 000, whose molecular structures are characterized by NMR, IR, and UV spectroscopy. The mesomorphic behavior of 2 is investigated by DSC, POM, and XRD: 2a exhibits smecticity in a temperature range as wide as over 100 °C (k 80.4 sA 194.8 i), while 2b di...