Research articles

Ion-conductive and electrochemical properties of solid polymer electrolytes based on poly(ethylene carbonate) (PEC) and magnesium bis(trifluoromethanesulfonyl)imide, Mg(TFSI)₂, with small amount of lithium bis(fluorosulfonyl)imide, LiFSI were investigated. The addition of LiFSI improved the ionic conductivity of PEC-Mg(TFSI)₂, from ~2.3 × 10⁻⁶ S cm⁻¹ to ~1.0 × 10^-5 S cm⁻¹ at 80 °C. Cyclic voltammetry measurements for PEC-based electrolytes revealed that the plating/stripping reaction of Mg/Mg²⁺ is enhanced by the addition of LiFSI.

High-molecular-weight (HM_w) sulfonated polyimide thin films with a semialiphatic main chain exhibited an oriented lamellar structure and high proton conductivity (1.5 × 10^-1 S cm^-1) under humidified conditions. Low-molecular-weight (LM_w) sulfonated polyimide thin films with the same semialiphatic backbone exhibited a nonoriented lamellar structure and low proton conductivity (3.0 × 10^-2 S cm^-1) under humidified conditions. The results indicate that, in sulfonated polyimide thin films with semialiphatic main chain, the lamellar orientation greatly contributes to the high proton conductivity.

We designed elastin-like proteins (ELPs) composed of repetitive VPGIG sequences with or without the RGD cell adhesion motif (ELP-RGD/ELP-Ctrl) and used tetrakis(hydroxymethyl)phosphonium chloride (THPC) as a chemical crosslinker to generate hydrogels. The ELP-RGD and ELP-Ctrl gels were used as substrates for cardiac differentiation culture of murine induced pluripotent stem cells (iPSC). Cells on the ELP-RGD gel showed four times higher expression of the contractile protein gene, troponin T type 2 (TnT2), than those on a collagen type I gel, which is an effective substrate for iPSC cardiac differentiation.

Carboxylated poly(arylene ether ketone)s with hyperbranched and linear architectures were synthesized by the self-condensations of aromatic dicarboxylic anhydrides. A linear poly(arylene ether ketone) was obtained from an AB monomer, 4-phenoxyphthalic anhydride, while a hyperbranched poly(arylene ether ketone) was obtained using an AB₂ monomer, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride. The method for the synthesis of the hyperbranched poly(arylene ether ketone) is notable because it provides a high ion-exchange capacity, above 7 mmol g⁻¹, through a one-pot polycondensation.

Organic–inorganic hybrid thin films containing [Ti₄(μ₃-O)(OiPr)₅(μ-OiPr)₃(O₃PPh)₃]·THF (TiOPPh) as element blocks were prepared via hybridization with the hydroxyl-substituted organic polymers (PVP, PSA, or PBE) by spin-coating. The hybrid thin films were characterized by AFM, DSC, and pencil hardness. The pencil hardness values of the PVP hybrid thin films were in the order 20 > 40 > 0 wt% and were dependent on the surface smoothness. When TiOPPh was reacted with excess ethanol, the core was retained. Therefore, the core of TiOPPh will be retained in the hybrid polymers.

The organogels, poly(styrene-co-divinylbenzene); PS gel, poly(styrene-co-divinylbenzene-co-vinylpyridine); PS-VP gel, poly(styrene-co-divinylbenzene-co-vinylbenzoic acid); PS-VBA gel, and poly(styrene-co-divinylbenzene-co-styrenesulfonate); PS-SS gel were prepared with limonene by varying concentration of cross-linker and comonomer to control the gels’ properties. The increase of cross-linker improved the mechanical strength. However, it reduced the solubility in limonene, resulting in the decrease of swelling ratio. The cationic gel shows adsorb ability to anionic compound while anionic gel appears the reverse phenomenon. The limonene organogels were used as lipophilic drug storage and controlled release of testosterone by dense of polymer network.

Hollow and solid fibers made of polyion complexes of chondroitin sulfate C (CS) and chitosan (CHI) were selectively fabricated using a coaxial two-phase microfluidic device. The selective fabrication was successfully achieved only by changing the solvent of the sheath flow that contained CS. Proteins and nanomaterials could be incorporated in both fibers by mixing them in the core flow, CHI-containing solutions. Results suggested the great potentials of microfluidic techniques for preparation of polysaccharide hollow and solid fibers.

UV light irradiation causes the unexpected structural transition from core–shell to Janus in droplets consisting of a poly(4-butyltriphenylamine) (PBTPA)/poly(methyl methacrylate) (PMMA) blend solution. We obtained a phase-separated structure formed by the evaporation of the solvent from polymer solution droplets dispersed in an aqueous solution containing a surfactant. It was also found that the transition was caused by UV light with a wavelength of 365 nm, which is mainly absorbed by PBTPA, indicating that this phenomenon is triggered by PBTPA.

10,10′-(1,4-Phenylene)bis(5,7,9-decatriynyl N-(butoxycarbonylmethyl)carbamate) 1 and its perfluorophenylene derivative 2 were synthesized. Upon UV irradiation, both of them showed excitonic absorption of polydiacetylene. In particular, 2 showed an absorption maximum at 743 nm, which was approximately 100 nm longer than that of conventional polydiacetylenes, and its solid-state polymerization scheme was investigated.

A palladium (Pd) was confined within poly(N-isopropylacrylamide)-based hydrogel particles (GPs) with different sized hydrogel network. Nanosized Pd was loaded in the GPs via ligation to tertiary amine group in the GPs. The size of gel network was tuned varying the feed ratio of crosslinker. The catalytic efficacies of Pd-loaded GPs were significantly higher than those of commercially available Pd-loaded supports in Suzuki coupling reaction under aqueous condition. Using the smallest gel network, Pd-loaded GPs achieved the highest turnover number for the catalytic reaction, owing to protection of Pd from aggregation.

The grain size was quantitatively evaluated on the free surface, and in the thickness direction. The grain growth on the free surface was very slow in the early stage of thermal annealing, then it shifted to a rapid mode with a power law (~t^0.7). While in the thickness direction, the growth followed a power law of t^1.72 until 1180 min, then it shifted to a slow mode with t^0.21. Furthermore, the oriented layer near the free surface was found to be as thick as 9.5 µm, indicating that grain growth serves as a propagator for the regular ordering of spherical microdomains and orientation of the bcc lattice.

Nanocomposites containing mesoporous silica (MPS) materials with various pore structures (SBA-15 and MCM-41 types) melt mixed into polypropylene (PP) or PP functionalized with hydroxyl groups (PPOH) were characterized by analytical pyrolysis techniques, such as evolved gas analysis (EGA)-mass spectrometry (MS) and heart-cut EGA-gas chromatography (GC)/MS, to evaluate the interactions between the polymer matrix and MPS and the pore filling of the MPS in the nanocomposite. The EGA-MS measurements revealed that nanocomposites with MPSs evolve specific degradation products, which can be attributed to strong interactions between the polymer molecules and the internal pores. The amount of these specific products increased upon increasing the pore size of the MPS and the hydroxyl content in the polymer matrix. Sufficiently large pores of MPS and high hydroxyl contents in the matrix appear to provide strong interactions because the MPS pores are well-filled with polymer molecules, which contributes to the improved physical properties of the nanocomposites.

Double helical polysaccharide, xanthan samples with varying molar mass were thermally denatured and renatured in dilute solutions. The molar mass decreased after denaturation and renaturation for samples with an initial molar mass of 10⁶ g mol⁻¹, but those for the samples with an initial molar mass of 10⁵ or 10⁷ g mol⁻¹ decreased only slightly. A model explaining this molar mass dependence of the denaturation and renaturation behaviors was proposed based on the experimental results.

Nanocomposites composed of mesoporous silica (MPS) materials with various porosity structures (two types of SBA-15 with pores of 4.4 or 8.0 nm, and MCM-41 with pores of 2.9 nm and polypropylene (PP) or functionalized PP containing hydroxyl groups (PPOH) were developed. The nanocomposite containing PPOH and SBA-15 with a pore of 8.0 nm showed higher toughness, stiffness, and transparency than the other nanocomposites.

Random copolymers of l-lactic acid (LLA) and glycolic acid (GA) [P(LLA-GA)] with LLA unit contents in the ranges of 0–20 and 73–100 mol% were crystallizable during precipitation or melt-crystallization. The GA units of the LLA-rich P(LLA-GA) copolymers were incorporated in a lattice of LLA unit segments, whereas the LLA units of the GA-rich P(LLA-GA) copolymers were incorporated in a lattice of GA unit segments. Even the incorporation of relatively small-sized GA units in relatively large-sized LLA unit segments strongly induced structural disorder in the crystalline lattice.

An ethylene glycol-based hexa-block copolymer with six different temperature-responsive blocks was prepared via a reversible addition-fragmentation chain transfer (RAFT) polymerization. 2-(2-Methoxyethoxy)ethyl methacrylate (MEO₂MA) and oligo(ethylene glycol) methacrylate (OEGMA) were selected as the ethylene glycol-based monomers. Each block exhibits a different LCST in aqueous solution owing to their different OEGMA contents.

Saturation transfer difference (STD) NMR analysis was performed to identify the titanium-binding peptide (TBP) sites that interact with the SiO₂ nanoparticle surface, and then Arg1 and Asp5 were identified to be in close contact with the surface. The structure of the TBP bound to SiO₂ determined by the NOESY measurement was well defined, and the Arg1 and Asp5 side chains face in the same direction. These results validates that the NH₂⁺ of Arg1 and the COO⁻ of Asp5 interact electrostatically with the SiO⁻ and SiOH₂⁺ on the SiO₂ surface, respectively.

We prepared microwave-responsive adhesives from second-generation acrylic adhesives and ionic liquids, and performed microwave-responsive “on-demand-peeling”. The response depended on the types and quantity of the ionic liquids. While the adhesive strength were maintained irrespective of the contents of ionic liquid in the adhesives, with/without microwave irradiation. The peeling of the adhesives was observed in less than 30 s after microwave irradiation. In this study, we proposed simple, conventional, and attractive preparation of microwave-responsive adhesives by adding ionic liquids.

Phosphate-functionalized acrylic materials were synthesized by free-radical polymerizations of MMA and DMP using the BPO-DMpT initiated reaction system. The resulting products were able to react with the HEMA monomer, thus yielding polymers with a chain structure of P(MMA-co-DMP)-b-PHEMA. Remarkably, incorporating DMP and/or PHEMA into PMMA main chain rendered a copolymer with low T_g while increasing the T_d intrinsic to PMMA. The enhancement of overall thermal stability of the acrylic materials is a feature of great interest for applications in bone cements and coating system additives.