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Cross-linked liquid-crystalline polymers show photoinduced deformation with change in molecular shape and alignment of the polymers. Polymer materials can transduce light energy to mechanical stress by macroscopic deformation of the polymers (photomechanical effect). Mechanism of the photoinduced deformation of the polymers is investigated. Three-dimensional movements of the liquid-crystalline polymers are achieved by lamination of the polymers into a flexible polymer sheet. This review described a short overview of recent developments in photomechanical effects mainly focusing on design of the polymer materials with photochromic moiety and applications to light-driven polymer actuators.
We survey recent studies about amphiphilic polyhedral oligomeric silsesquioxane (POSS)-based functional materials and explain the design concepts for applying the peculiar characteristics of POSS for the material properties. In the former parts, we introduce the examples concerning POSS-based ionic liquids. In the latter parts, we also mention the application of POSS-based materials for bio-relating functional materials. Based on our recent works, the unique properties of the amphiphilic POSS are reviewed.
This focus review describes a brief overview of our recent achievements on the fabrication of self-assembled nanostructures and following transformation by external stimuli, such as thermal treatment, metal coordination and ultraviolet irradiation. Some stimuli-responsive organic molecules possessing alkyl tails working as adsorption and interaction sites were synthesized to allow the spontaneous formation of various two-dimensional (2D) nanopatterns on a highly oriented pyrolytic graphite (HOPG). The 2D molecular arrangements were investigated by using scanning tunneling microscopy at HOPG/1-phenyloctane interface.
Polymer micro- and nano-particles have attracted much attention because of their promise for a variety of applications. This focus review introduces an emerging method for producing nanostructured polymer particles, called self-organized precipitation (SORP), and gives an overview of controlling the internal structure of polymer particles by using various polymer blends and block-copolymer systems. The possible applications and future prospects of this technology are also discussed.
Biomineralization, the process by which organisms create a variety of sophisticated composites such as bone and shell, is an ideal model toward materials fabrication in an environmentally friendly way. This article reviews recent progress in the biomineralization-inspired synthesis of polymer–inorganic composites including (1) polymer–calcium carbonate thin films synthesized by interaction among insoluble polymer, soluble acidic polymer, and inorganic ions; (2) polymer nanogel–calcium phosphate nanoparticles synthesized on scaffolds of hydrogel nanoparticles; and (3) colloidal silica nanoparticles made to self-assemble into anisotropic structures by interaction with block copolymers.
Poly(arylene ether ketone)s composed of 1,8-diaroylenenaphthalene moiety, a non-coplanarly accumulated aromatic-rings unit, have been successfully synthesized via nucleophilic aromatic substitution polycondensation of 1,8-bis(4-fluorobenzoyl)-2,7-dimethoxynaphthalene with several arene diols under mild conditions. The polymers show high glass transition temperature (Tg), poor solubility and good film-forming ability by heat casting.
The oxidative polymerization of thiophene derivatives were carried out using palladium (II) acetate as a catalyst in the combination with copper (II) acetate and trifluoroacetic acid under oxygen atmosphere. The poly(3-hexylthiophene) (P3HT) obtained by palladium catalyzed polymerization showed that head-to-head content was richer than authentic one prepared by a conventional oxidant, and that maximum absorption, and luminescence wavelengths of the P3HT are blue-shifted to 338 and 534 nm in ultraviolet and photoluminescence spectra, respectively. The catalytic system was also applied for the polymerization of 3,4-disubstituted thiophene monomers.
The giant single crystals of isotactic polypropylene (iPP) were obtained by a specific kinetic path through the mesophase of iPP. The obtained crystallites showed a very high melting temperature immediately near the iPP’s equilibrium melting temperature. The crystallites have bamboo leaf-like or needle-like morphology having several tens μm in length, several μm in width and 88 nm in thickness. The number density of the crystallites in a unit volume was controlled by adjusting the heating rate, resulting in well-isolated single crystals.
In situ small-angle X-ray and neutron scattering (SAXS and SANS) measurements were conducted on an isotropic blend of deuterated polyethylene (97 wt%) and hydrogenated polyethylene (3 wt%) during uniaxial drawing at 125 °C to clarify the formation mechanism of shish-kebab from isotropic film. Figure shows that 2D SANS and SAXS patterns in the various drawing ratio, RD, conditions. The drawing direction is longitudinal. In RD=8, the streak-like scattering in the normal direction of drawing became stronger only in the SANS, showing that more hydrogenated polyethylene chains were merged into the shish.
The elastic properties of Tetra-polyethylene glycol (PEG) gel, four-armed PEG network gel, are studied by simulation for deformation of elastic networks containing defects randomly introduced to the network. This network model well reproduces the experimental results of Tetra-PEG gel. In particular, the stress-strain curve of the gel prepared at chain overlap concentration agrees with that of a regular network without defects. As the defect density increases, the Young’s modulus linearly decreases. The fracture and spatial inhomogeneity of the networks are also investigated by the simulation.
This study demonstrated that synchrotron radiation ultra-small angle X-ray scattering (SR-USAXS) enable us to evaluate the outermost surface and ‘buried’ periodic structure without any pretreatment and sample damage. Surface and ‘buried’ nanostructure were fabricated on poly(lactic acid) film by nanoimprint lithography. The resulting films were characterized by SR-USAXS. The size of surface and ‘buried’ structure were successfully determined by the analysis of scattering pattern.
Polyvinylidene fluoride particles were chemically modified by grafting with polystyrene without preliminary treatment of the fluoropolymer surface by using surface-initiated atom transfer radical polymerization. Formation of polystyrene brushes, which may form a uniform polystyrene layer over the surface of fluoropolymer particles, was observed by scanning electron microscopy.
A series of soluble and autophotosensitive hyperbranched polyimides were successfully prepared. The hyperbranched polymer (HBPI) films showed excellent solubility, low dielectric constant and a minimum birefringence value as low as 0.0026 at 650 nm. In addition, HBPI-1 and 3, exhibited excellent optical properties and good photolithographic properties, may be considered as promising processable high-temperature materials for applications in microelectronic and optical devices.
Sulfonated polymers are promising polyelectrolyte for polymer electrolyte fuel cells (PEFCs) in the next generation. We found that the sulfonated polyelectrolyte can wrap multi-walled carbon nanotubes (MWNTs). After the reduction of Pt salt in the presence of the polyelectrolyte-wrapped MWNTs, Pt-nanoparticles below 5 nm in diameter with a narrow distribution were found to be homogeneously loaded. The composites are composed from the electron conductor, proton conductor and the catalyst metal, which are all necessary for the electrocatalyst for fuel cell and are promising materials for PEFC in the next generation.
Polyurethane networks (PUN) were synthesized by reacting poly(ethylene glycol) and hexamethylene diisocyanate with poloxamer Tetronic 701 or poly(ɛ-caprolactone)s triols. The hydrophilic/hydrophobic ratio was varied by selecting the appropriate amounts of monomers, and its effect on swelling behavior and thermal properties was analyzed. Drug-release studies evidenced that these materials hold promise as implantable drug-delivery devices and antimicrobial coatings.
Dendrimers are attractive polymers with a well-defined structure and multivalent terminal groups. We have designed a novel type of peptidomimetic based on dendrimer by modifying the amino acids at the periphery of the dendrimer. The dendritic peptidomimetic containing Pro and Arg was bound to a model protein, amphiphysin II SH3 domain, at a similar level to a model binding peptide, a Pro-rich sequence of dynamin.
The intercalated structures for the high-impact polystyrene (HIPS) nanocomposite materials that were prepared with 5 wt% Cloisite 30B (C30B) (a) and 5 wt% Cloisite 10A (C10A) (b) are shown in the transmission electron microscopy images. Although an intercalated structure is present in the sample (b), some individual platelets can also be observed because the material remains thermally stable when it undergoes melt compounding. The higher thermal stablility of the HIPS/C10A nanocomposite materials in comparision with the HIPS/C30B nanocomposite materials was proved by the mechanical testing and the rhecometer and thermal analysis.
Monodisperse polystyrene particles were prepared by enzymatic emulsifier-free emulsion polymerization using a horseradish peroxidase (HRP)/H2O2/β-diketone system in water. The resultant polymer particles were stabilized by the β-diketone moieties located at the surface of the particle. Enzymatic emulsifier-free emulsion polymerization might offer a practical method for the preparation of polymer particles under mild enzymatic conditions (that is, room temperature and surfactant-free).
The glycosaminoglycan model polymers with poly-γ-glutamate backbone were synthesized by conjugation with a p-aminophenyl 6-sulfo-β-GlcNAc or taurine. Poly-γ-glutamate with 6-sulfo-β-GlcNAc exhibited the inhibition activity on aggregation of Alzheimer amyloid beta peptide(1–40). On the other hand, the polymer with taurine didn't show the inhibitory activity on aggregation of amyloid beta peptide and rather accelerated the aggregation.
