Abstract
Phenylene-thiophene-based liquid crystalline π-conjugated copolymers bearing mesogenic groups as side chains were synthesized via a Stille polycondensation reaction and confirmed to exhibit a nematic liquid crystal phase at appropriate temperatures. The formation of a nematic phase, but not a smectic phase indicates cooperation of the main chain and side chain in the formation of a nematic main-chain/side-chain liquid crystal phase. The generation of polarons in the main chain as charge carriers during in-situ vapor doping of iodine is confirmed to increase with a doping progresses, exhibiting Dysonian paramagnetic behavior typical of conductive polymers.
Highlights
Liquid crystal (LC) polymers exhibit both liquid-like fluidity and crystal-like molecular order.Rigid and stick-shaped compounds with low molecular mass and rigid polymers with high molecular weight often display an LC phase under appropriate conditions
It is generally known that the introduction of LC groups into the main chain allows polymers to form an LC phase as a sidechain LC polymer [3, 4]
The absorption bands near 400 nm are attributable to the π–π* transition of the main chain, and the absorption intensities of the polymers increase with thiophene number in the monomer repeat unit of the polymers
Summary
Liquid crystal (LC) polymers exhibit both liquid-like fluidity and crystal-like molecular order. Chemical doping with a suitable acceptor dopant such as iodine results in the generation of free radicals (polarons) on the main chain of the conjugated polymers. Polarons act as electrical conduction carriers in π-conjugated polymers, and the generation of polarons in such polymers during chemical doping processes can be monitored by electron spin resonance (ESR) spectroscopy [15, 16]. A phenylene monomer bearing a pyrimidine-type LC group was synthesized, and the compound was demonstrated to exhibit both nematic and smectic phases. Copolymerization of this monomer with thiophene monomers was conducted to afford π-conjugated LC copolymers. The optical properties, liquid crystallinity, and iodine doping effects of these π-conjugated LC copolymers were characterized as examples of a new type of aromatic LC conjugated polymer
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
