Articles in 2017

Polymer nanocomposite membranes based on sulfonated poly (ether ether ketone) (SPEEK) with single-walled carbon nanotubes and fly ash were prepared and their physicochemical properties were studied in detail. The scanning electron microscopy and X-ray diffraction analyses confirm the successful incorporation of carbon nanotubes into the polymer matrix. The SP-CNT-FA-8 membrane provides the highest tensile strength of 74.4 MPa. The incorporation of inorganic nanofiller and fly ash can retard the oxidative degradation of SPEEK, which leads to the expansion of thermal stability. The excellent thermal and mechanical stabilities as well as relatively high proton conductivity of the synthesized electrolyte membranes facilitate them to be used in fuel cells.

The grain size was evaluated by atomic force microscope observation for the thin film specimen of the polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene triblock copolymer in which the perpendicularly oriented polystyrene cylinders are existing, while that in the interior of the specimen was evaluated by the small-angle X-ray scattering measurements. Both results for the grain growth on the surface and in the interior of the sample exhibited power-law behavior with the same extent of the exponent (~0.45).

Three types of block copolymers consisting of polyfluorene and polytriarylamine with benzothiadiazole (BT) moiety are synthesized and characterized to evaluate the effect of chromophore location on electroluminescent performance. BT unit is incorporated at the junction of both blocks (BP 1) in the polytriarylamine block (BP 2) and in the polyfluorene block (BP 3). Electroluminescent device based on BP 1 exhibits the best performance. This result is reasonably explained by taking into consideration the difference of recombination probability in the phase-separated active layers.

The regioselective halogen–magnesium exchange reaction of 4-(5″-hexylpyridine-2″-yl)-3-methoxy-2-(5′-bromothiophene-2′-yl)-5-bromothiophene (M3) with i-PrMgCl·LiCl, Kumada coupling polymerization using Ni(dppp)Cl₂ at the refluxing temperature and optoelectronic characterization of regiocontrolled oligo(bithiophene) (P3′) were investigated. The ultraviolet–visible and cyclic voltammogram measurements indicated that P3′ has the more planar conformation, increased highest occupied molecular orbital energy level and narrower bandgap energy as compared with a polythiophene derivative without the methoxy group. The non-covalent S···O interaction was supposed to be a reason for the planar conformation, which was supported by the theoretical density functional theory calculation.

Hydrogel microspheres (microgels) are composed of crosslinked hydrophilic or amphiphilic polymer chains and exhibit fascinating properties. Their typical size range (<~10 μm) and their excellent properties promise a variety of attractive applications as for example templates, microreactors, catalysts, coatings, and drug carriers. Against this background, we have conducted systematic research on microgels including their synthesis, characterization, assembly, and applications. In this focus review, we summarize recent results of microgel research mainly from our group and those of our collaborators.

This focus review describes the utilization of M13 phage, a filamentous virus, for the development of a novel class of materials. Recently, the preparation of ordered structures composed of M13 phages based on liquid crystal formation has generated great interest as a means of utilizing the outstanding properties of phages for the development of novel soft materials. The combination of genetic engineering-based functionalization and liquid crystal formation can be effectively used to develop structurally regular hybrid materials composed of M13 phages and inorganic or organic materials. M13 phages can be used for various functional soft materials.

Organic–inorganic hybrids containing [Ti₄(μ₃-O)(OiPr)₅(μ-OiPr)₃(O₃PPh)₃]·thf (TiOPPh) as element-blocks were prepared by hybridization with silicone polymers (poly(dimethylsiloxane) (PDMS), poly(methylsilsesquioxane) (PMS) or poly(ethoxysilsesquioxane) (PEOS)), the hydroxyl groups substituted organic polymers (poly(vinyl alcohol) (PVA), poly(4-vinylphenol), poly(styrene-co-allyl alcohol) or poly(bisphenol A-co-epichlorohydrin) (PBE)) or poly(methyl methacrylate) (PMMA). The concentration of TiOPPh was increased to 40 wt% to form free-standing hybrid films with PDMS, PMS, PVA and PBE polymers. The tensile strengths and elongations of PMMA and PVA films were higher improved than only polymers because TiOPPh acted good crosslinkers.

On the gelation of thermogelling polymer solutions, polymer chain transfer between the micelles and subsequent aggregation of the micelles are important steps. In this study, we investigated polymer chain transfer by the fluorescence resonance energy transfer (FRET) method to reveal its role in the sol-to-gel transition. We synthesized amphiphilic triblock copolymer attaching naphthalene or dansyl groups at termini, tri-PCG-nap and tri-PCG-dan. The FRET behavior of the mixture of tri-PCG-nap/tri-PCG micelles and tri-PCG-dan/tri-PCG micelles was investigated.

An unidirectionally deformable material with reversibility was achieved. The method relies on crystal crosslinking of pillared-layer metal–organic framework (PLMOF), followed by exchange of the pillar ligand to monotopic ligand. The obtained crosslinked MOF crystal exhibited reversibly unidirectional compression and expansion upon cycles of drying and immersion in good solvents. The preservation of layer structure enabled to confirm the unidirectional deformation not only macroscopically but also microscopically. Our strategy will be a promising general method for construction of anisotropic deforming materials, which can be often seen in biological systems or mechanical devices.

Ionic liquid (IL)/sulfonated polyimide (SPI) composite membranes exhibit high carbon dioxide (CO₂) permeability with good CO₂/N₂ selectivity. CO₂ permeation coefficients (P_CO2) are higher than 400 Barrer at 30 °C when the composite membranes include 75 wt% of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide. The IL/SPI composite membranes also exhibits excellent mechanical properties (Young’s modulus ⩾10 MPa) and can be processed into thin and uniform membranes. These characteristics are preferable as CO₂ separation membranes.

Poly(glycerol adipate) and poly(glycerol adipate)-co-ethylene glycol prepolymers are produced through catalyst-free polycondensation reaction. The resulting elastomers are products of crosslinking procedures and are fully characterized, showing an ease of final property tunability. Further cytotoxicity and adherence analyses based on mouse embryonic fibroblasts suggest their excellent potential for soft tissue engineering.

Complexation of cisplatin with stabilized ‘Pluronic’ aggregates, containig functional poly(acrylic acid) moieties was investigated as platform for drug delivery application. The advantageous characteristics of the system involve high drug payload, excellent stability upon storage and sustained drug release of the conjugated drug over 2 weeks.

The blends of epoxy/amine/acrylic block copolymer (BCP) provided nanophase structures by optimizing the dissolution process of BCP. The thermal dissolution of the BCP in the amine promoted the in situ formation of carboxylic acids. Tuning the amount of carboxylic acids changed the phase structure, such variations led to the formation of different types of micelle structures, such as curved lamellae, coexisting of worm-like micelles and vesicles, and spherical micelles from epoxy/amine/BCP blends having the same composition.

PIXEO BP-S tape used for Large Hadron Collider and its chemical structure.

We designed and prepared thermal-responsive poly-vinylamine-containing micro-gel particles (GPs) with an optimized volume-phase transition temperature (VPTT) by modifying the concentrations of the monomer, crosslinker and surfactant. The amine concentration of the GPs was also maximized. The GPs are capable of reversibly capturing and releasing CO₂ in response to a small temperature change.

Scattering function of semi-rigid cyclic polymers analyzed in terms of worm-like rings: cyclic amylose tris(phenylcarbamate) and cyclic amylose tris(n-butylcarbamate).

Novel polyester resin particles useful for toner with characteristics such as a narrow particle size distribution, a uniform and non-spherical particle shape, and high melt elasticity at high temperature with low-temperature meltability were developed. These characteristics were achieved by the application of three key technologies to the conventional dissolution suspension method, and they contribute to energy savings and high image quality for toner.

The adsorption properties of cationic polyelectrolytes (poly (diallyl dimethylammonium chloride) (PDDA) and poly (allylamine hydrochloride) (PAH)) on solid surfaces were observed using quartz crystal microbalance. The response of adsorption was different with the change of polyelectrolyte solution concentration and pH value. The influence of pH value on the PDDA adsorption process is inconspicuous, while PAH shows strong dependence on the pH value. Furthermore, the change of molecular conformation of polyelectrolyte molecule is the main factor that affects the adsorption properties and structures.

Cellulose-based hydrogels have attracted much attention due to their potential for a wide variety of applications. Recently, we demonstrated the production of nanoribbon network hydrogels through a crystallization-driven self-assembly of cellulose oligomers synthesized by enzymatic reactions under macromolecular crowding conditions. However, the detailed mechanism underlying hydrogel production remains unclear. This study investigated the effect of solution viscosity on hydrogel production by using a highly branched polymer, Ficoll. We propose that a certain level of solution viscosity is an essential requirement for hydrogel production.