This study presents a transparent hybrid (ionic and dielectric) gel actuator system based on polyvinyl chloride (PVC) and ionic liquid (IL) gels with dibutyl adipate (DBA) as the plasticiser.

Polymer films made by UV-curable liquid crystalline (LC) monomer have both characters of the external stimulus responsiveness of LC and flexibility of polymer chains. Therefore, polymer film made by UV-curable LC monomer are expected as soft actuators. By incorporating photothermal conversion materials in polymer film, the macro shape of film can be controlled by light irradiation. In this study, a polymer film made by UV-curable LC monomer containing gold-coated fine particles was prepared and its bending motion induced by near-infrared laser irradiation was studied. When the film is irradiated with near-infrared laser, it bends. We also investigated the dependence of the concentration and distribution of gold-coated fine particles in the film, and irradiation time and intensity for the bending displacement.

The 19th Optics of Liquid Crystals (OLC2021) Satellite Workshop (SWS) 2022 took place in Bankoku Shinryokan, Nago City, Okinawa from 25 until 30 of September 2022. Last year, OLC2021 was affected by the fifth wave of COVID-19 in Japan, and it was not possible to hold a face-to-face meeting with participants on-site. The venue was also the location of the G8 Summit 2000, and it is located on a cape protruding into the sea in central Okinawa. A total of 32 oral invited lectures were given and 27 posters were presented. There were about 60 participants, four scientists came to Japan from overseas to give an invited lecture. All oral lectures were delivered simultaneously live and via Zoom and were made available free of fees to all OLC2021 participants. On Sunday 25th, a public lecture was held as a related event. Ten groups of elementary and junior high school students in Okinawa attended the lecture and listened carefully and with great interest to the research on neutrinos and gravitational waves from two professors at Kyoto University. On Monday, after the opening, Prof. H. Yokoyama of Kent State University, USA, gave a lecture on the podium and Prof. I. Smalyukh of Colorado University were shown on the screen through Zoom. After that, there were two domestic presentations in the morning and two in the afternoon, followed by online presentations from Prof. S. Žumer and Prof. M. Ravik of the University of Ljubljana, Slovenia. All the presentations were followed by lively Q & A from the venue audience. After these talks, there were 14 poster presentations in the area behind the venue, which provided plenty of space for the prevention of the novel corona virus. On Tuesday, after an online lecture by Prof. I-C. Khoo of the Pennsylvania State University, USA, followed by on-site lectures by Prof. M.H. Godinho of the NOVA University Lisbon, Portugal (Figure 1), Prof. G. Chu of Alto University, Finland and Prof. W. Lee of the National Yang Ming Chiao Tung University, Taiwan, two presentations in the afternoon, and an online lecture by Prof. I. Dierking of The University of Manchester, UK, and 13 poster presentations were followed by lively Q & A, as during the previous day (Figure 2). On Wednesday, after four lectures, a group photograph was taken in front of the venue under the clear skies at Okinawa as shown in Figure 3. In the afternoon of Wednesday, a conference excursion to Zakimi Castle Ruin was organised, which took participants to one of the world heritage sites of Japan. The castle was built in the beginning of the 15 century and now lays in ruins except for

Two series of regio-isomeric mesomorphous, luminescent and conductive compounds, based on a ditriphenylenothiophene core (α/β-DTPT), were successfully synthesized by the Suzuki–Miyaura cross-coupling/Scholl cyclo-dehydrogenation reactions tandem.

We report a straightforward and generic synthesis of several new series of annulated π-extended poly-(hetero)aromatic hydrocarbons (PAH), with carbazole, fluorene and fluorenone central building blocks by the Suzuki-Miyaura/Scholl tandem reactions. The corresponding series of ditriphenylene discogens with a carbazole or a fluorenone central core, respectively, possess hexagonal columnar mesophases with broad mesophase ranges and high clearing points, as well as demonstrate a strong aggregation tendency in organic solvents as supergelators. The laterally-substituted ditriphenylene mesogens based on dimethyl-fluorene core exhibit a rich polymorphism with rectangular and hexagonal columnar mesophases from low temperatures onward, whereas their dioctyl-fluorene homologues melt directly into the isotropic liquid without showing mesophases. These latter family of compounds are luminescent with very high fluorescent quantum yields, of around 70 % in solution, and show outstanding photocurrent behavior with charge carrier mobility in the 10−2 cm2 V−1 s−1 range, as measured by photocurrent transient time-of-flight (TOF) technique. This straightforward molecular design and simple synthetic strategy proved to be both potent and resilient, and could be generally applied to the fabrication of a great variety of other heteroarene molecular systems as organic semiconductors and electroluminescent materials for potentially low-cost applications.

A series of bent-core paramagnetic ionic liquid crystals derived from stable radicals, 6-oxoverdazyl and 1,4-dihydrobenzo[e][1,2,4]triazin-4-yl, and containing the N-methylimidazolium group were prepared and their mesogenic, magnetic and ion conductive properties were investigated. The ion pairs form fluid smectic phases above 100 degrees C, in which ionic layers are separated by paramagnetic layers. Ion conductivity for two selected derivatives is in a range of 10(-5) -10(-8) S cm(-1) and activation energies Ea are about 1.5 eV. Magnetic susceptibility measurements (SQUID) of pristine solid samples revealed liquid-like molecular arrangement in the paramagnetic layers and weak antiferromagnetic interactions. (C) 2021 Elsevier B.V. All rights reserved.

Mesomorphous butterfly-like shape molecules based on benzodithiophene, benzodithiophene-4,8-dione and cyclopentadithiophen-4-one core moieties were efficiently synthesized by the Suzuki-Miyaura coupling and Scholl oxidative cyclo-dehydrogenation reactions' tandem. Most of the butterfly molecules spontaneously self-organize into columnar hexagonal mesophase. The electron-deficient systems possess strong solvent-gelling ability but are not luminescent, whereas the electron-rich terms do not form gels but strongly emit light between 400 and 600 nm. The charge carrier mobility was also measured by time-of-flight transient photocurrent technique in the mesophases for some of the compounds. They display hole-transport performances with positive charge mobility in the 10(-3) cm(-2) V-1 s(-1) range, consistent with the high degree of ordering and stability of the columnar superstructures. In particular, the mesogen with a benzodithiophen-4,8-dione core shows ambipolar charge carrier transport with both high electron (mu(e)=6.6x10(-3) cm(-2) V-1 s(-1)) and hole (mu(h)=4.5x10(-3) cm(-2) V-1 s(-1)) mobility values.

Different types of platelet-shaped graphene were used as structural and conductive filler of the carbon nanotube (CNT) porous electrode films of a dry-type polymer actuator consisting of CNT, ionic liquid, and a base polymer to enhance actuation performance. The strain and blocking force were evaluated from the bending motion of the actuator with a frequency response from 10 to 0.005 Hz. Ten types of CNT electrode film were prepared by varying the surface areas and added amounts of the graphene. When the same amount of platelet-shaped graphene (50 mg) as that of CNT (50 mg) was added to the CNT electrode, the generated force became almost twice that of CNT (50 mg) without any graphene additives, while the observed displacement remained a similar value. The addition of platelet-shaped graphene improves the expansion and generated stress of the three-layer actuator consisting of CNT electrodes. (C) 2020 The Japan Society of Applied Physics

We report herein the design and synthesis of some novel liquid crystalline semiconductors constructed from a biologically and pharmacologically active building block molecule, namely 6-methoxy-2-(4-methoxyphenyl) benzo[b]thiophene, presenting efficient luminescence and medium charge mobility rate. A first series of mesogenic 2-phenylbenzothiophene derivatives (nPBT) was simply and rapidly obtained in good yields by successive demethylation/allcylation reactions of the available methoxy precursor. The further stepwise oxidations moreover resulted in two new sets of the corresponding sulfoxide (nPBTO) and sulfone (nPBTO(2)) derivatives, respectively, that were also mesomorphic. The liquid crystalline behaviour was comprehensively characterized by DSC, POM and SAXS: all compounds exhibit smectic-like behaviour in agreement with their calamitic shape. More specifically, mesogens nPBT showed a SmA phase, with in addition, a higher ordered smectic phase at lower temperature. As for the oxidized mesogens, they displayed a SmA phase only, and over particularly large temperature ranges for the nPBTO with longer chain lengths (n >= 8). The photo-physical properties have also been studied both in solution and thin films, and the molecules were found to display strong absorption in the UV/vis domain and intense luminescence in the range of 400-650 nm (yellowish green light) in high quantum yields (up to 62%). Both absorption and luminescence were also found to be affected by the oxidation of the benzothiophene moiety. Finally, the semi-conducting behaviour of three PBT compounds in the various mesophases was investigated by photocurrent TOF technique. Hole mobility rates of ca. 4 x 10(-3) cm(2) V-1 s(-1) were measured in the lower temperature ordered mesophase for all of them, with the best performances (temperature range and mobility values) however obtained for the shortest homolog (n = 6). With such highly reasonable mesomorphic, light-emitting and semiconducting functional features, as well as being cheap and easy to synthesize and to process, these materials become very attractive and may be incorporated into various kinds of electronic devices (OFET and OLED).

Planarization of the central paramagnetic unit facilitates the formation of an antiferroelectric B2 phase, exhibiting tri-stable electro-optical switching and photoconductivity.

Board-like liquid-crystalline semiconductors based on the dithieno[3,2-b;2',3'-d]thiophene (DTT) substructure were synthesized and their thermal, self-assembly, optical, and semiconducting properties investigated. These sanidic compounds, bearing eight peripheral chains, are mesomorphic and spontaneously self-assemble into columnar hexagonal mesophases (Colhex ) over broad temperature ranges, as confirmed by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. Strong blue photoluminescence with absolute quantum yields up to 33 % were measured. These compounds also form blue-light emitting gels in various organic solvents. The fibrillar-like morphology of these gels, reminiscent of the columnar structure, and stabilized by efficient intermolecular interactions, was characterized by scanning electron microscopy. The charge carrier mobility of these π-extended mesogens was measured by time-of-flight transient photocurrent technique in the Colhex mesophase, and showed good hole-transport performance with charge carrier mobility of 10-3  cm2  V-1  s-1 .

Fused-thiophene discotic liquid crystals were designed and easily synthesized by Suzuki coupling and FeCl3 oxidized tandem cyclodehydrogenation reactions, including homo- and cross-coupling reactions. The resulting hexagonal and rectangular columnar mesomorphic supramolecular structures formed were characterized by polarizing optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The charge carrier transport properties in the mesophases of two of the synthesized fused-thiophene discogens were measured by transient photocurrent time-of-flight (TOF) technique, revealing fast hole transport values in the range of 10(-3) to 10(-2) cm(2) V-1 s(-1), thus demonstrating potential applications in electronic devices. The luminescent sanidic mesogens, with different extended pi-conjugated systems, also emit blue, green, or red light, with absolute photoluminescent quantum yields as high as 18 %.

A homologous series of disc-like 1,3,6-trisubstituted benzo[e][1,2,4]triazin-4-yls 1[n] was synthesized and their structural, thermal, optical, magnetic, and electric properties were investigated. The results demonstrate that all members of the series display a Col(h) phase with clearing temperatures depending on the length of the alkoxy chains at the N(1) position, hence the shape of the disc. Powder XRD and magnetic data indicate a gradual change in the column diameter and magnetic behavior in the series in transition from half-disc in 1[0] (antiferromagnetic interactions) to full-disc geometry in the 1[12] homologue (ferromagnetic interactions with J/k(B)=+7.5 K). Studies of binary systems revealed that a 1 : 1 mixture of 1[0] and 1[12] exhibits modest stabilization of the Col(h) phase with an expanded range, and magnetic behavior typical for 1[0] in the rigid phase obtained from the melt. Electric measurements demonstrated hole mobility of similar to 10(-3) cm(2) V-1 s(-1) and dark conductivity of similar to 10(-11) Scm(-1) in the mixture and individual compounds. The latter is enhanced up to 4 times by simultaneous illumination with UV light.

Benzothienobenzothiophene (BTBT) liquid-crystalline semiconductors are arousing a lot of interest due to their long-range ordered, self-organizational abilities and high-charge carrier transport properties. In this work, we report the design and the straightforward synthesis of a homologous series of compounds containing the BTBT substructure by the successive Suzuki cross-coupling and FeCl3 oxidative Scholl cyclodehydrogenation reaction. Target p-conjugated aromatic, H-shaped sanidic mesogens self-organize into a classical hexagonal columnar mesophase over wide temperature ranges as deduced from polarized optical microscopy (POM), differential scanning calorimetry (DSC), and small-angle X-ray scattering (SAXS) investigations. UV/Vis absorption and photoluminescence spectra, measured in both solution and films, revealed strong photoluminescence with high quantum yields. The charge carrier mobility measured by the time-of-flight (TOF) technique showed a balanced ambipolar hole and electron mobility in the range of 10(-3) cm(2) V-1 s(-1) between 100 and 230 degrees C in the mesophase. These BTBT-based columnar liquid crystals may represent attractive candidates to be incorporated within one-dimensional organic optoelectronic devices.

We have developed stacked nanocarbon polymer actuators that are composed of several nanocarbon polymer actuator films using nonwoven fabric as insulation layers. The nonwoven fabric prepared through electrospinning methods has extremely-low-density structures, which do not significantly prevent the motions of each nanocarbon actuator layer. Therefore, stacking several thin nanocarbon polymer actuators using nonwoven fabric as insulation layers is expected to increase generated force without decreasing the displacement of a one-layer actuator. We have prepared stacked actuators with one, two, three, four, and seven layers using this method. The displacement and blocking force of these actuators are measured and compared with those of one-layer actuators of different thicknesses. Displacement is weakly dependent on the thickness of the actuator films of the stacked actuators. On the contrary, it decreases considerably as the thickness of the actuator film of the one-layer actuator increases. In both cases, blocking force is proportional to the thickness of actuator films. We have developed a stacked actuator model based on a trilayer actuator model and confirmed the experimental results using the model.

In this study, the platelet-shaped graphene was used as a conductive additive in porous electrodes of a dry-type polymer actuator consisting of carbon nanotube (CNT), ionic liquid, and a base polymer to improve actuation properties. The generated strain was estimated from the bending motion of the actuator in the frequency range from 0.005 to 10 Hz. Ten different types of electrode film were prepared by changing the mixing amounts and surface areas of the platelet-shaped graphene. When a small amount of graphene (30 mg) relative to CNT (50 mg) was added to the CNT electrode, the strain was increased to be almost twice larger than that of CNT (50 mg) without any additives. The strain coefficient of the three-layered actuator with CNT electrodes with graphene additives is positively correlated with the capacitance per volume of such electrodes.

Discotic polyaromatic liquid crystals exhibiting 2D columnar mesophases are actively investigated for their potential utilization as one-dimensional organic semiconductors, due essentially to their long-range order self-organization and high charge carrier transport ability. The much less reported nematic-containing discotic materials have however been recently found to be of industrial importance too. In this context, highly conjugated fluorene-bridged triphenylene triads have been designed with the aim of inducing room temperature nematic phases. In our approach, the length of the alkyl chains bore by the central fluorene unit was changed in order to constrain the space-filling, to modulate the intermolecular pi-pi interactions, and to control the tendency of the molecular triads to stack into columns, and the subsequent aggregation of the columns in specific ways. This strategy was successful, and in addition to the naturally expected two-dimensional columnar mesophases, most triads exhibit the more elusive columnar nematic phase, as only the orientational-type long-range order is preserved. Photoluminescence, measured in both solution and thin films, revealed strong blue emission, characteristic of the fluorene moiety, with impressively high quantum efficiency. Charge carrier mobility measurements revealed novel p-type molecular semiconductors with hole transport mobility in the range of 0.2-2 x 10(-3)cm(2) V(-1 )s(-1) in the mesophases (Col(rec), Col(hex), and N-col) and up to 5 X 10(-4) cm(2 )V(-1)s(-1) in the isotropic phase. Reasons for the occurrence of these mesophases and their supramolecular structures are discussed along with the effects on the semiconducting properties.

A new variety of non-symmetrical triphenylene-based discogens has been synthesized by intramolecular Scholl cyclodehydrogenation reaction of kinked terphenylenes using the FeCl3/MeNO2 couple as an efficient oxidant. The “Janus-like” tetrakis(alkoxy)triphenylene discogens containing electron-withdrawing groups, such as cyano-, chloro- and fluoro-substituents, or electron-donating moieties, such as carbazole, thiophene and naphthalene at the opposite of the alkylated side were prepared in good to high yields. Polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) investigations revealed that six of the 14 discogens synthesized exhibit a hexagonal columnar mesophase. These chromophores emit bright blue light from 350 nm to 500 nm in solution depending on the extension of their π-conjugation. In addition, all six columnar liquid crystals show non-dispersive time-of-flight photocurrent transportation, with charge carrier drift mobility in the range of 10−3 to 10−4 cm2 V−1 s−1, higher or in the same range as their symmetrical hexa(alkoxy)triphenylene parent compounds.

We have investigated synthesis as well as purification of 5,5'''-bis(tridecafluorohexyl)-2,2':5',2 '':5 '',2''' quaterthiophene (BFH-4 T, n -type organic semiconducting material) using supercritical carbon dioxide (scCO(2)) as a green solvent. BFH-4T was obtained in good selectivity and high yield by TDAE/PdC12-catalyzed reductive coupling reaction of 5-bromo-5'-(tridecafluorohexyl)-2,2'-bithiophene in scCO(2). We have also successfully established purification of the reaction mixture by passing scCO(2) in the reaction vessel. The product was yellow powder of BFH-4T with purity of more than 99% and Pd catalyst was not contained. (C) 2017 Elsevier Ltd. All rights reserved.