Thermoreversible helical fibers from photoreactive triphenylene-derived liquid crystals in liquid paraffin.

Liquid crystalline triphenylene derivatives, TPC1p-n (n = 6, 12, 14, 16) were prepared using p-alkoxycinnamate as the [2+2] photo-cyclization site. TPC1p-n (n = 12, 14, 16) showed Colr phase and gave crescent-shaped or helical fibers after UV-irradiated in liquid paraffin solutions at 90 and 110 °C in the Colr temperature range. The apparent photoreaction products were shown to be thermally reversible, i.e. they dissolved in liquid paraffin at high temperatures and reappeared on cooling, indicating that they were aggregates of oligomerized TPC1p-n. The reaction mechanism was discussed in terms of the structure of the liquid crystalline phase.

Biomolecular Adsorption to Interfacial Single Particle Layer of Organo-Modified Nanodiamond and Its Second-Order Structure.

Modifying the surface of nanodiamonds, which have antibacterial properties, with organic molecular chains enables biomolecular adsorption on a single particle layer on the water surface. For organo-modification, long-chain fatty acids act on the terminal hydroxyl groups present on the nanodiamond surface, and cytochrome C protein and trypsin enzyme are used as biomolecules. Cytochrome C and trypsin introduced into the subphase were electrostatically adsorbed onto the unmodified hydrophilic surface of the organo-modified nanodiamond monolayers on the water surface. The ampholyte protein is thought to exhibit Coulomb interactions with the positively charged unmodified nanodiamond surface. The protein adsorption was supported by morphological observations and spectroscopic properties; circular dichroism spectra suggested denaturation of the adsorbed proteins. However, the biopolymers could maintain their second-order structure even under a high-temperature environment, after being slightly denatured and adsorbed to the template. The nanodiamonds form excellent templates for structural retention in the atmosphere while yielding minor denaturation corresponding to the chirality of biomolecules upon adsorption.

Immobilization of Trypsin from the Subphase to the Langmuir Monolayer of Fluorocarbon-Modified Single-Walled Carbon Nanotube and Its Activity Maintenance.

Single-walled carbon nanotubes (SWCNTs) synthesized by the improved arc discharge method were modified with a fluorocarbon chain, and the maintenance of trypsin activity upon adsorption from the subphase to the interfacial monolayer of SWCNTs was evaluated. The adsorption of trypsin on the fluorocarbon-modified SWCNT monolayer was confirmed by morphological and spectroscopic evaluations. Fiber morphology studies revealed that the fluorocarbon-modified SWCNT monolayer was covered by trypsin, and a trypsin-derived amide band was detected in the infrared spectra of the multilayers. After adsorption onto the fluorocarbon-modified SWCNT film, the ability of trypsin to cleave the fluorescent casein chain was maintained even at 160 °C. Furthermore, circular dichroism (CD) spectra showed that the second-order structure of the activity of trypsin adsorbed on the fluorocarbon-modified SWCNT was maintained up to nearly 200 °C. At 200 °C, the enhancement of emission intensity by casein chain cleavage was negligible, and the CD signal resulting from the negative Cotton effect was completely altered at 250 °C.

Spherical Particle Formation that Deteriorates Thixotropic Property and its Suppression Strategy for Diamide-Based Additives having Two-Hydrocarbons.

Spherical particle formation degrades the performance of castor-oil-derived thixotropic additives, which are widely used to a dripping preventing agent in automobile paints and household waste oil treatment agent. Double-chain-type diamide is a heat-resistant thixotropic additive that causes nanofibrosis; its entanglement and gelation embracing solvent molecules-originating from the abundant intermolecular hydrogen bonds-and easy forming/rupturing tendency result in spherical particle formation, which can be confirmed by the temperature and time of reserve heating. Diamides with two hydrocarbons that have undergone thermal treatment leading to spheroidization were found exhibit significantly different sublimation/pyrolysis temperature, melting temperature, and crystal orientation than non-treated diamides. By comparing with the change observed under more extreme heating conditions, it can be considered that the amide bond site would increase the bond length and suppress the degree of freedom of rotation just before bond cleavage. In this state, verification of the origin of spherical particle formation by using the Langmuir-Blodgett method revealed that anisotropic suppression of hydrogen bonding occurs. In addition, it was found that spheroidization can be suppressed by adding a growth aid when preheating is conducted under a certain condition.

Extension of "Interfacial Adsorption Denaturation" Behavior Interpretation Based on Gibbs Monolayer Formation by Biomolecules.

Using glucose oxidase and salmon testis-derived DNA molecules, we sought to extend the recently proposed idea of interfacial adsorption denaturation. The surface pressure-time (π-t) isotherm of the glucose oxidase Gibbs monolayer exhibited a rapid increase in surface pressure and a relatively prompt transition to a liquid condensed film. The appearance of this rapid liquid expansion phase occurred much earlier than that previously identified for lysozyme, trypsin, cytochrome C, and luciferase. This experimental finding was linked to the number of hydrophobic residues in the constituent unit, and the number of hydrophobic residues in glucose oxidase was the highest among these biomolecules. On the other hand, DNA molecules do not have such hydrophobic groups, or present a positive surface on the π-t curve. However, interfacial adsorption occurred, and the existence of molecules at the air/water interface was confirmed, even in the two-dimensional gas phase state. Furthermore, it was confirmed that an increase in surface pressure was detected during the formation of a mixed film of DNA molecules and biomolecules, forming a stable Gibbs monolayer. This mimic the behavior of mixed monolayer formation with matrix molecules in Langmuir monolayers. Moreover, it was clarified that the interfacial adsorption denaturation behavior changed when pH dependence was evaluated considering the isoelectric point of the biomolecular group.

Preparation of Hexagonal Plate-like ZnO Single-crystal Particles in the Presence of Anionic Amphiphiles.

In this study, we synthesized ZnO particles using anionic amphiphiles as an additive. While the single-crystal particles prepared in the absence of such amphiphiles had a hexagonal rod-like shape, those fabricated using anionic amphiphilic molecules had a hexagonal plate-like shape. The anionic amphiphiles inhibited crystal growth in the c-axis direction of ZnO. This demonstrated that the anionic surfactants served as crystal-growth-directing agents, controlling the shape of the ZnO particles.

Creation of Highly Ordered "Nano-Mille-Feuille" Hard/Soft Nanoparticle Multilayers with Interparticle Cross-Linking by Diacetylene-Containing Chains.

In this study, we attempted to create a precise nanostructure in which hard and soft layers were alternately stacked with a period of 5 nm. Such a periodically stacked structure can be used as a model material to elucidate the origin of the innovative mechanical property improvement proposed for Mg alloy systems. The soft layer was a single layer of nanoparticles made of a ternary copolymer containing a carbazole ring and both hydrocarbon and fluorocarbon chains. The hard layer was a single-particle layer made of magnetite nanoparticles; the surface of these particles was modified with long-chain diynoic acid. The multilayers of each single-particle layer were 54% crystalline and ordered with a D001 crystallite size of approximately 20 nm. The nano-mille-feuille structure, in which the hard and soft layers are repeated in a single-digit nanoperiod, was 56% crystalline and ordered with a D001 crystallite size of approximately 15 nm. Infrared absorption spectroscopy and X-ray photoelectron spectroscopy did not show any loss of both hard and soft layers. Even when the thickness/number of layers was changed variously, no remarkable decrease was observed in the order. Cross-linking between particles by ultraviolet irradiation polymerization was performed for the direct evaluation of the mechanical properties of this structure in the future. Even after topochemical polymerization between the modified chains, the order of the particle stacking structure was maintained.

Polyguanamine Derivative-Based Supramolecular Assemblies with Multiple Hydrogen Bonding and Their Metal-Scavenging Abilities.

Polyguanamine derivatives having cyclic moieties constituted by two phenyl and two triazine rings have been synthesized, and a supramolecular organization based on their multiple hydrogen-bonding ability was investigated. The obtained polyguanamine derivatives with cyclic moieties were transparent and amorphous in the bulk state and showed excellent mechanical strength emanating from multiple hydrogen bonds, owing to the abundant amino groups present in the structure. These polyguanamine derivatives formed stable monolayers at the air/water interface. The multilayers were transferred using the Langmuir-Blodgett method, and they formed highly periodic layered structures. To evaluate the metal scavenging ability of the cyclic moieties, the metal ions, Cd2+, Nd3+, and Pd2+, were introduced in the subphase. As a result, the cyclic moieties in the polyguanamine derivatives efficiently captured Cd2+, Nd3+, and Pd2+ metal ions. After the metal was captured, the layered structure of each organized film showed higher periodicity because of rearrangement. Moreover, the annular part had a cup-like structure, and the steric size effect of the ring influenced the metal scavenging.

Creation of High-Density and Low-Defect Molecular Films with a Flat-on Conformation by Interfacial Organization of Triphosphasumanene Trisulfides.

This paper focuses on the formation of high-density, low-defect monolayers of triphosphasumanene trisulfides, which are newly synthesized electronic and geometric Janus-type molecules, in a flat-on conformation. Although the molecules stack easily because of the developed π-conjugated plane, their application as a metal coating in a flat-on conformation via an interfacial molecular film enables the work function to be tuned. Surface pressure-area isotherms of the triphosphasumanene trisulfides show a two-dimensional phase transition at the air/water interface. Atomic force microscopy observations of the transferred monolayer and in- and out-of-plane X-ray diffraction patterns of the corresponding multilayers reveal that this phase transition occurs from the flat-on to the end-on conformation. The X-ray diffraction patterns obtained in the two directions completely reversed before and after the phase transition, indicating that the molecular arrangement that is generated by layers of molecular films and resultant molecular stacking is similar. The flat-on conformation of the molecules was evident from the out-of-plane X-ray diffraction and polarized infrared spectroscopy results, which indicate that a large, low-defect monomolecular film is obtained using a toluene solution with a small diffusion coefficient. The spectroscopic results reveal triphosphasumanene trisulfide aggregation in the organized molecular film, suggesting high-density molecular packing.

Division of roles of modified chains in organo-magnetic nanoparticles using Organo-modified agents having hydrophilic reactive polar groups at both ends: Formation of high-density single-particle layers and bioconjugation.

The behavior of an organo-modified chain that changes its role depending on the environment has been investigated. Long-chain carboxylic acids having a hydrophilic reactive polar group at both ends were allowed to act on magnetic nanoparticles to produce organo-modified particles. These amphiphilic organo-magnetic nanoparticles are synthesized by the reaction of a hydroxyl terminal group on the outermost surface of the magnetic particle and a carboxylic acid. With spreading at the air/water interface, an extremely condensed single-particle layer on the water surface was formed. It is evident that a long-chain carboxylic acid having a hydrophilic group at the terminal acts as a hydrophobic chain. Furthermore, when a Lysozyme enzyme as an ampholyte was allowed to act from the subphase, we observed that it adsorbed at the end of the modified chain. This implies that a hydrophilic group facing the subphase side exists. This phenomenon also occurred when the terminal comprised amino or carboxyl groups. Therefore, we observed that the surface-modified chain having the same chemical structure changed its role depending on the environment, and it can function as both a hydrophilic and a hydrophobic group.

Elucidation of the Origin of Thixotropic-Inducing Properties of Additive Amphiphiles and the Creation of a High-Performance Triamide Amphiphile.

The spontaneous growth of helical fibers of amphiphilic diamide derivatives containing hydrocarbons with asymmetric carbon centers in their constituent hydrocarbons was investigated. 12-Hydroxystearic acid and a gemini-type surfactant obtained by the bimolecular condensation of this compound with hexamethylenediamine both impart thixotropic ability to a solvent. Although this thixotropic behavior is based on the growth of hierarchical crystalline nanofibers in the solvents, the degree of fiber growth itself was not the origin of the thixotropy. In this study, it has adopted the methods of the Langmuir monolayer and Langmuir-Blodgett films as technique to selectively and individually evaluate the behavior of 12-hydroxyl stearyl and/or stearyl chains themselves. The ability to impart thixotropy to the solvent via fiber organization was related to the intermolecular hydrogen bonding between the added amphiphiles. Additionally, homogeneous right-handed helical fibers were formed in the spin-cast films of the diamide derivatives, and a positive Cotton effect was observed in their circular dichroism spectra. It is suggested that fibers that do not form helical arrangements cannot impart sufficient thixotropy to the solvent even when extensive fiber growth is achieved, and the structure-dependent development of chirality is the driving force. In addition, to further the development of highly functional thixotropic agents, a trefoil-like triamide derivative containing three chains was synthesized. By using this molecule, solvent gelation occurred at 78% as an addition to the diamide case, and a supramolecular assembly was formed in the corresponding two-dimensional film.

Dependency of Nanodiamond Particle Size and Outermost-Surface Composition on Organo-Modification: Evaluation by Formation of Organized Molecular Films and Nanohybridization with Organic Polymers.

The formation behavior of organized organo-modified nanodiamond films and polymer nanocomposites has been investigated using nanodiamonds of several different particle sizes and outermost-surface compositions. The nanodiamond particle sizes used in this study were 3 and 5 nm, and the outermost surface contained -OH and/or -COOH groups. The nanodiamond was organo-modified to prepare -OH2+ cations and -COO- anions on the outermost surface by carboxylic anion of fatty acid and long-chain phosphonium cation, respectively. The surface of nanodiamond is known to be covered with a nanolayer of adsorbed water, which was exploited here for the organo-modification of nanodiamond with long-chain fatty acids via adsorption, leading to nanodispersions of nanodiamond in general organic solvents as a mimic of solvency. Particle multilayers were then formed via the Langmuir-Blodgett technique and subjected to fine structural analysis. The organo-modification enabled integration and multilayer formation of inorganic nanoparticles due to enhancement of the van der Waals interactions between the chains. Therefore, "encounters" between the organo-modifying chain and the inorganic particles led to solubilization of the inorganic particles and enhanced interactions between the particles; this can be regarded as imparting a new functionality to the organic molecules. Nanocomposites with a transparent crystalline polymer were fabricated by nanodispersing the nanodiamond into the polymer matrix, which was achievable due to the organo-modification. The resulting transparent nanocomposites displayed enhanced degrees of crystallization and improved crystallization temperatures, compared with the neat polymer, due to a nucleation effect.

Two-dimensional growth of crystalline nanofiber fabricated from Gemini-type amphiphilic diamide derivative inducing the thixotropic property.

The formation of a nanofiber morphology at the mesoscopic scale and the molecular-level packing of a gemini-type amphiphilic diamide derivative with two hydrocarbons were investigated from two perspectives. First, it was confirmed that a diamide derivative with two hydrocarbons forms crystalline nanofibers even in a monomolecular layer. The height, thickness, and lattice spacing of the two-dimensional orthorhombic system of this crystalline nanofiber in the monolayer of a diamide derivative with two hydrocarbons are 5, 30, and 0.4nm, respectively. Next, it was determined that the fibrous growth of the diamide derivative with two hydrocarbons, which contributes to the thixotropic ability, can be achieved by the addition of a quaternary ammonium cation with long chains, modified with montmorillonite. Here, the interlayer spacing was about 3.8nm for the organo-modified montmorillonite and was consistent with the layer spacing of the diamide derivative having two hydrocarbons. The surface pressure-area isotherms of the mixed monolayers suggest that there is miscibility between these materials. From "the affinity due to the van der Waals interaction between the terminal groups of the alkyl chains" and the "similarity of layer spacing," epitaxial growth is expected.

Control of Fine Structure in "Polymer Nanosphere Multilayered Organization" and Enhancement of Its Optical Property.

This paper reports on a new functionality exhibited by "polymer nanosphere multilayered organization", a new type of molecular organization, and the relationship between their structure and function. The polymer nanosphere multilayered organization is a fine structural material formed by the accumulation of single-particle layers of a hydrophobic polymer at the air/water interface; these single-particle layers have uniform height along the c-axis. By employing the "alternate compression-relaxation method", high-density, low-defect particle layers are formed with a clear increase in their crystallite sizes. In the case of a ternary comb copolymer containing a carbazole ring, one particle is formed by the assembly of approximately 60 units of collapsed monolayer-like double layers. This structure is stabilized by the formation of side-chain crystals in the interlayer, with oriented π-π stacking of carbazole rings, resulting in enhanced fluorescence emission intensity.

Fabrication of Transparent Nanohybrids with Heat Resistance Using High-Density Amorphous Formation and Uniform Dispersion of Nanodiamond.

A new technology for the production of transparent material using a "crystalline" polymer is proposed in the present study. Further, transparent and flexible crystalline polymer nanohybrid film containing well-dispersed nanodiamond filler was fabricated. Partially fluorinated crystalline polymer with switchboard-type lamellae results in high transparency as a consequence of the formation of a high-density amorphous structure based on high-temperature drawing just below the melting point at 110 °C. Although the formation of nanohybrid materials composed of fluorinated-polymer/organo-modified nanocarbon is generally difficult, we confirmed the formation, via melt-compounding, using atomic force microscopy and wide-angle X-ray diffraction. Even though the polymer matrix/nanodiamond hybrid has remarkable aggregation properties, a well-dispersed state was achieved because of improvement in wettability obtained through surface modification of filler. The resulting nanohybrid demonstrates transparency, increased thermal degradation temperature, and enhanced mechanical properties, which seem to be derived from the nucleation effect caused by the adsorption of the terminal polymer chain onto the organic modifier.

Creation of giant two-dimensional crystal of zinc oxide nanodisk by method of single-particle layer of organo-modified inorganic fine particles.

In this study, the formation and structure of a single-particle layer of organo-zinc oxide are investigated using surface-pressure-area (π-A) isotherms, out-of-plane X-ray diffraction (XRD) analysis, and atomic force microscopy (AFM). Further, techniques for achieving the solubilization of inorganic fine particles in general solvents have been proposed, and a single-particle layer has been formed using such an inorganic solution as a "spreading solution" for an interfacial film. Surface modification of ZnO is performed using a long-chain carboxylic acid. Accordingly, a regular arrangement of ZnO can be easily achieved in order to overcome the relatively weak van der Walls interactions between inorganic materials. A condensed Langmuir monolayer of these particles is also formed. A multiparticle layered structure is constructed by the Langmuir-Blodgett (LB) technique. Out-of-plane XRD measurement results for a single-particle layer of organo-ZnO clearly show a sharp peak at 42 Å. This peak is attributed to the distance between ZnO layers. The AFM image of this single-particle layer of organo-ZnO shows a particle assembly with a uniform height of 60 nm. These aggregated particles form large two-dimensional crystals. In other words, a regular periodic structure along the c-axis and a condensed single-particle layer had been fabricated using Langmuir and LB techniques.

Creation of high-density and low-defect single-layer film of magnetic nanoparticles by the method of interfacial molecular films.

A technique to solubilize fine magnetic inorganic particles in general organic solvents is proposed via surfaces modification by long-chain carboxylic acids. This organic modification should overcome the relatively weak van der Waals interactions between the nanoparticles, allowing the formation of ordered arrangements of the modified Fe3O4 and CoFe2O4 materials. Using nanodispersions of these organo-modified magnetic nanoparticles as "spreading solutions", Langmuir monolayers of these particles were formed. Multiparticle layered structures were constructed by the Langmuir-Blodgett (LB) technique. The fabrication of single- and multiparticle layers of organo-modified magnetic nanoparticles was investigated using surface pressure-area (π-A) isotherms, out-of-plane X-ray diffraction (XRD), in-plane XRD, and atomic force microscopy (AFM). The out-of-plane XRD profile of a single-particle layer of organo-modified Fe3O4 clearly showed a sharp peak which was attributed to the distance between Fe3O4 layers along the c-axis. The AFM image of single-particle layer of organo-modified CoFe2O4 revealed integrated particle organization with a uniform height; these aggregated particles formed large two-dimensional crystals. For both nanoparticle species, regular periodic structures along the c-axis and high-density single-particle layers were produced via the Langmuir and LB techniques.

Morphological transition of a conductive molecular organization with non-covalent from nanonetwork to nanofiber.

The formation of nanofiber morphology at a mesoscopic scale, and molecular level stacking of a tetrathiafulvalene (TTF) derivative with a chiral group were investigated by the one-dimensional growth method in interfacial molecular films. Monomolecular films of a TTF derivative with a chiral borneol group display a two-dimensional phase transition at the air/water interface. At high surface pressures, nanonetwork domains are formed, where the TTF molecular planes are densely packed with an interlayer distance of 4.1 Å. The formation of this network is attributed to the organized aggregation of the TTF derivatives, which is a result of strong intermolecular interactions. Subsequently, the growth of morphology is encouraged by the application of the one-dimensional growth method at low surface pressure conditions, varying compression speeds, and subphase temperatures. At low surface pressure and a subphase temperature of 15 °C, the TTF derivatives aggregated as nanofibers with close packing of molecules. Upon raising the subphase temperature, the thickness of the nanofibers was found to increase and hence, spontaneous morphogenesis at the air/water interface was achieved.

The role of modifying molecular chains in the formation of organized molecular films of organo-modified nanodiamond: construction of a highly ordered low defect particle layer and evaluation of desorption behavior of organic chains.

The role of organo-modifying molecular chains in the formation of molecular films of organo-modified nanodiamond is discussed herein based on interfacial chemical particle integration of organo-modified nanodiamond having a particle size of 5 nm. The surface of nanodiamond is known to be covered with a nanolayer of adsorbed water. This water nanolayer was exploited for organo-modification of nanodiamond with long-chain fatty acids via adsorption, leading to nanodispersion of nanodiamond in general organic solvents as a mimic of solvency. The organo-modified nanodiamond dispersed "solution" was used as a spreading solution for depositing a mono-"particle" layer on the water surface, and a Langmuir particle layer was integrated at the air/water interface. Multi-"particle" layers were then formed via the Langmuir-Blodgett technique and were subjected to fine structural analysis. The effect of organo-modification enabled integration and multilayer formation of inorganic nanoparticles due to enhancement of the van der Waals interactions between the chains. That is to say, the "encounter" between the organo-modifying chain and the inorganic particles led to solubilization of the inorganic particles and enhanced interactions between the particles, which can be regarded as imparting new function to the organic molecules. The morphology of the single-particle layer was maintained after removal of the organic region of the composite via the baking process, whereas the regularity of the layered period was disordered. Thus, the organic chains are essential as modifiers for maintenance of the layered structure.

Fabrication and structure of "polymer nanosphere multilayered organization".

We constructed a multiparticle layered organization of aromatic polyamides with rigid main chains and flexible side chains by the Langmuir-Blodgett (LB) technique, which resulted in a highly regular arrangement along the c-axis. The particle arrangement was estimated by performing out-of-plane X-ray diffraction (XRD) analysis and atomic force microscopic (AFM) observation. The results suggest that a double-particle layered structure (Y-type) is formed by the LB technique, forming amphiphilic particles at the air/water interface. Copolymers with highly hydrophobic carbazole contents and both hydrogenated and fluorinated side-chains also formed a single-particle layer at the air/water interface and exhibited multiparticle layers by a LB technique. Therefore, it is possible to control the formation of single- and double-particle layered structure using these techniques. Further, it was found that multiparticle layered organization of polymer nanospheres and polymer nanosheets could be formed simultaneously with the same component material.