Nakasugi Shigemasa, Kang Sungmin, Chang Tso-Fu Mark, Manaka Takaaki, Ishizaki Hiroki, Sone Masato, Watanabe Junji
Advanced Technology Research Department, LG Japan Lab Inc., 1-2-13, Takashima, Nishi-ku, Yokohama, Kanagawa 220-0011, Japan.
Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan.
J Phys Chem B. 2023 Jul 27;127(29):6585-6595. doi: 10.1021/acs.jpcb.3c02259. Epub 2023 Jul 13.
A dimeric molecule, di-5(3FM-C4T), with fluoro-substituted mesogenic cores composed of three-aromatic rings and linked by a pentamethylene spacer is prepared. Di-5(3FM-C4T) forms the ferroelectric nematic (N), ferroelectric smectic-A (SmAP), and polar isotropic (Iso) phases. The N phase is composed of molecules in U-shaped conformation that behave like polar rod-like molecules. The reversal spontaneous polarization () is approximately 8 μC cm, which is extremely large and reflects the huge dipole moment (11.2 D) of the one-side mesogenic core. On the other hand, the SmAP phase is formed by bent-shaped molecules. The N-SmAP phase transition thus follows the conformational change of molecules. The reversal of the SmAP phase is around 4 μC cm, which is half of that in the N phase, and this is an expected value from the bent shape of the molecules. It is interesting that the highest temperature Iso phase still exhibits the polar structure and possibly retains some polar aggregation of molecules in small domains. The three polar phases exhibit the dielectric mode due to the collective polarization fluctuation at around 100 Hz, giving the high dielectric constant over 8000.
制备了一种二聚体分子di-5(3FM-C4T)，其具有由三个芳环组成并由亚戊基间隔基连接的氟取代介晶核。di-5(3FM-C4T)形成铁电向列相（N）、铁电近晶A相（SmAP）和极性各向同性相（Iso）。N相由呈U形构象的分子组成，其行为类似于极性棒状分子。反转自发极化（）约为8 μC/cm²，极大，反映了单侧介晶核的巨大偶极矩（11.2 D）。另一方面，SmAP相由弯曲形分子形成。因此，N-SmAP相转变遵循分子的构象变化。SmAP相的反转约为4 μC/cm²，是N相的一半，这是由分子的弯曲形状得出的预期值。有趣的是，最高温度的Iso相仍呈现极性结构，并且可能在小区域内保留了一些分子的极性聚集。这三个极性相由于在约100 Hz处的集体极化涨落而呈现介电模式，给出超过8000的高介电常数。
