Recent Developments in Liquid Crystal Polyesters

As the properties of LC polyesters can be used for most of the applications from engineering plastics/composite/blend to optical data recording, the research on this material for furthering its applicability is expected to continue for years to come. New LC polyesters are also being reported. 

Fullerene is reported to be used as as a stabilizer in the synthesis of liquid-crystalline polyesters. The use of fullerene (-0.01 wt % based on the monomer weight) as a stabilizer in the synthesis of a liquid-crystalline (LC) polyesters enabled it for high-temperature acceptorless poly-condensation. The temperature interval of reaction may be widened to 220°C. The presence of fullerene also makes it possible to eliminate high temperature crosslinking side reaction [154]. 

Molecular chirality has profoimd effect when it is introduced into LC polymers. The chiral LC phases having helical morphology are finding potential applications in optics and electrooptics [155]. Polymers having molecular asymmetry in the backbones are commonly seen in natural life forms. The DNA, collagen, and myosin, the well known biopolymers, display minute control over their molecular helicity. The configuration of the chiral center in the nucleotide or peptide backbone decides the twist senses of the chiral structures [156]. 

Chiral LC polyesters is ported by synthesizing from (R)-(-)-4tf-[d-[2-(p-hydroxy-o-nitrophenyloxy)-l-propyloxy]-l-undecyloxy -4-biphenylcarboxylic acid via an A-B type condensation polymerization. It exhibits SC, SA, and TGBA LC phases. Flat-elongated lamellar crystals are also found in both SA and SC phases. Right -handed helical lamellar crystals are also observed which has identical crystal structure as the flat-elongated ones [161]. 

The non-chiral main chain LC polyester also studied for their shear alignment. The chain-folded lamellae formation was observed. X-ray measurement carried out on the main-chain LC polyesters to observe how smectic liquid crystal gets oriented under steady shear flow. When the temperature is increased the mesogens within 

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