Masao Honma

New Ferroelectric Liquid Crystals with Spontaneous Polarization Exceeding 10−7C/cm2 and Their Electrical and Optical Properties

Abstract New series of ferroelectric liquid crystals with neighbouring chiral carbons or a chiral carbon with C—CI binding next to the molecular dipole moment (C=O) are synthesized utilizing isoleucine, valine, leucine, amylalchol and 2-amino butanoic acid as starting materials and are found to possess extremely large spontaneous polarization exceeding 3 × 10−7C/cm2 and dielectric constants larger than 7000. These compounds are found to exhibit a novel dielectric behaviour such as hysteresis in the temperature dependence due to the strong molecular interaction with surfaces. The response of electro-optic elements prepared with these ferroelectric liquid crystals is found to be very fast, in the μsec range, even at room temperature.

Ferroelectric Liquid Crystal with Extremely Large Spontaneous Polarization

The greatest value ever reported for spontaneous polarization, as high as 4.2×10-8 C/cm2, is observed in DOBA-1-MBC. The relaxation frequency of this material determined from frequency dependence of the dielectric constant is higher than that of DOBAMBC by more than one order of magnitude. DOBA-1-MPC also indicates large spontaneous polarization as high as 1.8×10-8 C/cm2. These characteristics are discussed in terms of molecular structure of these ferroelectric liquid crystals.

Synthesis and ferroelectric properties of new series of ferroelectric liquid crystals

Abstract Four new series of ferroelectric liquid crystals (p-alkoxybenzylidene-p′-amino-1p″-methylbutylcinnamate, p-alkoxybenzylidene-p′-amino-1p″-methylpropyl-cinnamate, o-hydroxy-p-alkoxybenzylidene-p′-amino-2p″-methylbutylcinnamate and o-hydroxy-p-alkoxybenzylidene-p′-amino-1p″-methylpropylcinnamate) have been synthesized. Mesomorphism and dielectric properties of these compounds are studied. Some compounds have extremely high spontaneous polarization.

Graphite film prepared by pyrolysis of bacterial cellulose

A new route of preparation of high quality of graphitized films has been demonstrated. Highly graphitized films with electrical conductivity as high as 6×103 S/cm have been prepared by pyrolysis of bacterial cellulose films at 2900 °C. These films can be well intercalated with acceptors and donors such as FeCl3 and K, resulting in the enhancement of conductivity. Temperature dependencies of thermoelectric power and electrical conductivity are similar to those of soft carbon.

Synthesis and properties of ferroelectric liquid crystals with large spontaneous polarizations

Abstract The synthesis and some properties of optically active materials derived from amino acids will be described. Also we will report the properties of some compositions consisted of the chiral compounds and achiral Sc compounds. They have fast switching times at around room temperature.

Electrical property of pyrolyzed bacterial cellulose and its intercalation effect

Abstract Bacterial cellulose (BC) film prepared utilizing Autobacter aceti AJ 12368 was pyrolyzed at various temperatures up to 3000°C. The film was well graphitized with the heat treatment temperature(HTT) above 2500°C. The sample with HTT of 2900°C exhibited conductivity exceeding 6000S/cm and thermoelectric power (TEP) of −2.9 μV/K. ESR spectrum also exhibited drastic change with HTT, indicating well graphitization. The pyrolyzed (BC) film with HTT of 2900°C was also well intercalated by both donor such as K and acceptor such as FeCl 3 , indicating conductivity higher than 55000 S/cm. Negative and positive TEPs were obtained in K and FeCl 3 intercalated samples, respectively. Electrochemical characteristics of pyrolyzed BC film were also clarified.

Dependence of Switching and Memory Times of Optical Switching Element Utilizing Ferroelectric Liquid Crystals on Thickness of Cell and Material

Switching times rise time, decay time and memory time, of various electro-optic effects in ferroelectric liquid crystals are found to be strongly dependent on the molecular structure, cell thickness and temperatures. Especially in TSM (transient scattering mode) operation, the rise time becomes shorter in liquid crystals with larger spontaneous polarization, at high temperatures and in thinner cell. The decay time is also shorter at higher temperatures, in thinner cells and also in materials with higher relaxation frequency of dielectric constant.

Synthesis of new ferroelectric liquid crystals and their novel ferroelectricity

A new type of ferroelectric liquid crystal, the 4′-alkoxybiphenyl-4-yl (2S,3S)-3-methyl-2-halogenopentanoates, has been synthesized; these compounds possess novel ferroelectricity, with spontaneous polarization and dielectric constant larger than 10–7 C/cm2 and 6000, respectively.