Liquid Crystalline Polyethers

摘要

The first part of this paper will review recent work from our laboratory on structural principles and their use in the synthesis of thermotropic-lyotropic main chain liquid crystalline (LC) polyethers. Two synthetic procedures, i.e., phase transfer catalyzed polyetherification and cationic ring opening polymerization of bridged bicyclic ethers will be described, and examples will be provided for the synthesis of polyethers containing flexible spacers, adn of quasirigid polyethers. A detailed discussion will be made on the influence of microstructural parameters such as constitutional isomerism, sequence distribution, composition, and of molecular weight, on the phase transitions of LC copolyethers. The second part of this paper will briefly discuss some of the first examples of micro-phase separated biphasic side chain LC polymers, i.e., polymers exhibiting two glass transition temperatures, one due to the independent motion of the main chain, the other due to the cooperative but independent motion of the side groups. Their behavior suggests that the miscibility between side groups and main chain has to be considered by the space concept in order to achieve highly decoupled side chain LC polymers.