Studies on the synthesis and properties of ferroelectric side chain liquid crystalline polyoxetanes

✍ Scribed by Li-Ling Hsu; Teh-Chou Chang; Wen-Liang Tsai; Chein-Dhau Lee

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 255 KB
• Volume: 35
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(199710)35:14<2843::aid-pola5>3.0.co;2-r

✦ Synopsis

Two series of novel ferroelectric liquid crystalline (FLC) monomers were derived from 3-(hydroxymethyl)-3-methyloxetane, used as the backbone unit, and 2-(S)-[2-(S)-methylbutoxy]propionic acid, as a chiral moiety. The corresponding polyoxetanes were prepared by ring-opening polymerization using BF 3 rOEt 2 as an initiator. In addition to the structure identification, their liquid crystal phase behavior and electrical properties are also studied. Before their connection to the chiral molecular moiety, two series of carboxylic acids, 4-{6-[(3-methyloxetan-3-yl)methoxy]alkoxy}benzoic acids and 4,4-[6-(3-methyloxetan-3-yl)alkoxy]biphenylcarboxylic acids, show the phase sequence K -Sc -I and K -Sc -N -I, respectively. After connection, the phase behavior of the corresponding chiral monomers is changed from K-Sc-I to K-Sc*-N*-I as well as from K-Sc-N-I to K-Sc*-Sa-I. Only the phase sequence K-Sc*-Sa-I is observed in both series of polyoxetanes. All of the synthesized monomers exhibited enantiotropic chiral smectic C(Sc*) phase. The monomers, with the biphenyl unit linked directly with a chiral center, possessed higher spontaneous polarization (P s ) values. Polyoxetanes possess a wide temperature range for the liquid crystal phase, about 120ЊC, and the Sc* phase range can be up to 95ЊC. However, the position of the biphenyl unit will not affect the spontaneous polarization of the synthesized side chain FLC polyoxetanes.