1207669-72-4Relevant articles and documents
Smectic aggregates of sheet-like side-chain liquid crystalline polyacetylenes directly formed during solution polymerization
Liu, Lu-Mei,Liu, Kai-Peng,Dong, Yu-Ping,Chen, Er-Qiang,Tang, Ben Zhong
, p. 6014 - 6023 (2011/10/19)
We have successfully synthesized two side-chain liquid crystalline polyacetylenes (denoted as P3-5 and P2-5) with the mesogenic units based on a "phenyl-ester-phenyl" motif directly linked to the semirigid polyacetylene backbone in a terminal-on mode without flexible spacer. During the polymerization catalyzed by Rh(nbd)[B(C6H5)4] in toluene, the resultant polymers (or oligomers) automatically precipitate out of the polymerization solution as red solids, which cannot be dissolved in common organic solvents. Wide-angle X-ray diffraction results confirm that the polymer precipitates possess a smectic (or sanidic) structure, suggesting that the molecules without flexible spacers are sheet-like and can stack parallel to each other during polymerization. We in situ monitored the solution polymerization and the aggregation processes using UV-visible and 1H NMR spectroscopy methods. The experimental results indicate that after reaching a critical molecular weight the P3-5 and P2-5 molecules self-aggregate in solution and that the smectic aggregation proceeds during the solution polymerization. An apparent first-order polymerization kinetics can be obtained after the polymerization and aggregation slowed down. The resultant polymers are cis-rich with the main-chain absorption at ～455 nm. This implies that a considerably long effective conjugation length is achieved in the sheet-like cis-rich polyacetylene derivatives.
