Electro‐optical behavior of ferroelectric liquid crystalline polyphenylene derivatives

Abstract

Liquid crystalline (LC) polyphenylene derivatives, such as poly(paraphenylene) (PPP), poly(meta-phenylene) (PMP), poly(meta-biphenylene) (PBP), and poly (meta-terphenylene) (PTP) derivatives, were synthesized through substitution of fluorine-containing chiral LC groups into side chains, with an aim to develop ferroelectric LC (FLC) conjugated polymers. All the polymers, except PTP, showed enantiotropic liquid crystallinities, where several types of mesophases were observed in both heating and cooling processes. Among them, PPP and PMP derivatives showed chiral smectic C (S C *) phases responsible for ferroelectricity. In fact, they exhibited quick response to electric field, in spite of high viscosities inherent to polymers, giving rise to switching times of less than 1 s between two S C states with reversely directed alignment. Hysteresis loops between the polarization and electric field were also observed for PPP and PMP. The spontaneous polarization (P S ) of PMP remained unchanged even after the electric field became zero, affording the residual polarization (P R ) whose value was the same as that of P S . This indicates that PMP has a prospective memory function based on FLC nature. The present study is the first report for realizing a quick switching in macroscopic alignment using electric field and also for generating a potential memory function in p-conjugated polymers. It is elucidated that unusual polymer main chains such as polyphenylenes can be used to prepare new ferroelectric polymers. V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: [3591][3592][3593][3594][3595][3596][3597][3598][3599][3600][3601][3602][3603][3604][3605][3606][3607][3608][3609][3610] 2008

Microbial cis-3,5-Cyclohexadiene-1,2-diol, Its Polymer Poly(p-phenylene), and Applications

“…5;Suda and Akagi 2008). These are attracting interest because they can afford anisotropies in electrical and optical properties when they are macroscopically aligned.…”

“…On the other hand, research on a series of DHCDs and their derivatives and new applications of the polymers would create many new opportunities for industry. , PMBP poly (meta-biphenylene), PMTP poly(meta-terphenylene) (Suda and Akagi 2008) …”

Liquid crystalline conjugated polymers and their applications in organic electronics

“…It is also noted that polyphenylene derivatives P44-P46 show one or more chiral smectic mesophases, for example, chiral smectic I (S I *) and chiral smectic J (S J *) phases for polymer P45, whereas only chiral smectic A (S A *) phase is observed for polymer P46. 60 No LC mesophase is found for polymer P47, because the neighboring mesogenic groups are too far to form LC aggregate.…”

“…[59][60][61][62][63][64] The chemical structures are shown in Chart 21. Ferroelectricity is required to have a spontaneous polarization that is generated by assembly of dipole moments.…”

Advances in liquid crystalline conjugated polymers

“…11 In addition, small-band gap LC conjugated polymers 12 based on benzonoid and quinoid resonance structures have been synthesized. Subsequently, ferroelectric LC (FLC) conjugated polymers consisting of acetylene, 13 thiophene, 14 phenylene, 15 or phenylenevinylene 9(c) unit cell were synthesized to achieve highly quick response to an electric force field during macroscopic alignment.…”