Research articles

The microwave heating technique has been widely used in various organic and inorganic syntheses, and it has been reported that this technique provides the desired compounds quickly and easily. In this work, we applied microwave heating to synthesize redox-active organic nanoparticles consisting of hyperbranched viologen units. By the precise temperature control afforded by use of microwave irradiation, we succeeded in controlling the growth and termination reactions kinetically and preparing viologen nanoparticles in one-pot. We also demonstrated that the size of the nanoparticles can be controlled by varying the temperature program.

A preparation of polyacrylate-based vitrimer-like elastomers with dynamic bond-exchangeable cross-links is demonstrated. The component polymer is a poly(ethyl acrylate)-based copolymer bearing pyridine groups randomly, which was cross-linked by a quaternization reaction of pyridine groups with dibromo cross-linkers (dibromo hexane). The bond exchange is induced via trans-N-alkylation of quaternized pyridines at high temperatures, which is revealed by temperature-ramp FT-IR, elongational creep, and stress-relaxation tests. Some useful functions of the present material, such as reprocessability, thermal and chemical recyclability, are provided due to the bond exchange nature.

A reduction-responsive oligonucleotide was successfully constructed by post-modification of an oligonucleotide with a diazo compound bearing a 4-nitrobenzyl group as a reduction-responsive cleavable moiety. High-performance liquid chromatography and mass spectrometry were used to reveal the introduction of the 4-nitrobenzyl group to the 5′-phosphate group of the oligonucleotide, and the subsequent reduction-triggered recovery of the original oligonucleotide. The protocol used for the preparation of this reduction-responsive oligonucleotide is simple and it will have various applications in the fields of chemical and synthetic biology.

Aliphatic polycarbonate (APC) macromolecular chain-transfer agents (macro-CTAs) with an allyl end group were successfully synthesized by cobalt-catalyzed epoxide/carbon dioxide copolymerization in the presence of allyl alcohol as a chain-transfer agent. The ring-opening metathesis polymerization of cycloalkene monomers using the obtained APC macro-CTAs yielded the corresponding APC-block-polycycloalkene copolymers.

Ralstonia eutropha is a hydrogen-oxidizing chemolithotrophic bacterium that can synthesize poly[(R)-3-hydroxybutyrate] [P(3HB)], which can be used as a biodegradable plastic. Various genes for carbonic anhydrase involved in CO₂ fixation are present in the genome of R. eutropha. In this study, we investigated the gene dosage effect of the β-carbonic anhydrase (can) gene on P(3HB) accumulation in R. eutropha under autotrophic and mixotrophic conditions.

Thickness changes in polyvinyl acetate thin films, during the temperature cycle across the glass transition temperature (T_g) has been studied in detail. Even after enough thermal treatment done at the high-temperature side of T_g, thickness increase during cooling (negative thermal expansion) is observed. On the other hand, slow thickness decrease is observed with aging at the high-temperature side of T_g. The above interesting phenomena can be well explained by the model considering the presence and changes of the interface layer.

When the radical polymerization inhibitor 1,4-naphthoquinone (NQ) acts on styrene, the radical capture reaction greatly contributes carbon atoms. In this study, the 1-phenethyl radical, which is a model for the growth radicals of polystyrene, was reacted with NQ using four radical sources, and we identified the reaction product. We confirmed that the same compound was formed upon addition of a small amount of NQ to heated styrene. The frontier orbital energy levels and reaction path energy diagrams were calculated, which provided numerical values to support our experimental results.

The solid-state structure of L₂AlEt is reported by X-ray diffraction. BnOH (1 equiv. to L₂AlEt) selectively reacts with ~0.5 equiv. of L₂AlEt to afford free L–H (~1 equiv.) while maintaining L₂AlEt (~0.5 equiv.). The stoichiometric balance suggests the formation of 0.5 equiv. of (BnO)₂AlEt. The ROP of CL via the synergic catalysis of the two coexistent Al-complexes, L₂AlEt (0.50 mol%) as a Lewis acid activator of CL and (RO)₂AlEt (0.50 mol%) as a nucleophile, is proposed.

The chain dynamics in a spin-coated poly(methyl methacrylate) (PMMA) film in solvent annealing was studied by in situ neutron reflectivity. The absorbed solvent molecules homogeneously distributed in the spin-coated film and the PMMA chain even near the substrate showed sufficient mobility in the solvent annealing process, while the chain mobility was strongly restricted at the substrate in thermal annealing. This result indicates that the solvent annealing method enables the equilibration of a spin-coated polymer film from the surface to the substrate interface.

Using the over-1000 nm near-infrared (OTN-NIR) dye IR-1061-loaded polymer micelles, IR-1061-loaded PEG-b-PCL micelles (OTN-PNPs) were successfully obtained using a simple one-pot preparation method. The OTN-PNPs showed strong OTN-NIR emission under physiological conditions. Furthermore, the OTN-PNPs were readily biodegradable; thus, it is anticipated that the renal clearance of the degraded material will occur after imaging experiments. Moreover, in vivo imaging of a live mouse was successfully performed. The blood vessels of a live mouse could be clearly illuminated using the OTN-NIR emission of OTN-PNPs. Therefore, the OTN-PNPs are promising candidates for NIR imaging probes.

Novel aromatic copolymers based on a thiazolothiazole (TT) unit were designed and synthesized as proton exchange membranes for polymer electrolyte fuel cells. Even a small amount of the TT unit (0.1–1 mol%) considerably affected the sizes of the hydrophilic and hydrophobic domains of the membrane surface. Furthermore, the TT-based membranes exhibited higher proton conductivities and lower activation energies than those of the parent membrane under various relative humidity conditions.

A robust, redox-active radical polymer, poly(TEMPO-substituted norbornene), was surface-grafted on an indium tin oxide glass substrate. The polymer brush functioned as a redox-induced ‘command surface’ to reversibly switch the alignment of chiral nematic liquid crystals and their light reflection with wavelength selectivity.

Epigenetics control carrier (EpC carrier) has been designed as a unique tool to control histone acetylation by simultaneous transfection of histone acetyltransferase gene and delivery of a histone deacetylase inhibitor.

The hydration behavior, intermediate water content and platelet adhesion level of four different aliphatic carbonyl polymers that have subtle differences in the backbone structure were investigated. The platelet adhesion was strongly related to the surface hydration and intermediate water content for the hydrated polymers. The ether bonds in the main chain has a significant role in hydration and poly(p-dioxanone) exhibits the lowest platelet adhesion level among four polymers. The other three polymers showed similar platelet adhesion levels. However, carbonate bonds contribute to the formation of more intermediate water than ester bonds.

We have demonstrated that the phase-transfer polycondensation of bisphenol A with 4,4'-dichlorodiphenyl sulfone catalyzed by 18-crown-6 provided poly(arylene ether sulfone)s with high molecular weights even in the non-dehydrated N,N-dimethylacetamide. The obtained poly(arylene ether sulfone)s showed similar or higher number average molecular weights (M_n) compared with that prepared by the conventional polycondensation using azeotropic distillation.

Highly stretchable hydrogel shows actuation behaviour upon irradiation of infrared (IR) light. The photothermal effect induced by heat from IR absorption causes cooperative change in the network alignments in the stretched sample.

The effectiveness of energy-resolved (ER) X-ray photoelectron spectroscopy (XPS) with synchrotron radiation (SR) soft X-ray source for analysis of the outermost chemical composition of polymer materials is demonstrated. The surface molecular aggregation state of poly(ethylene glycol) (PEG)/poly(perfluorooctylethyl acrylate) (PFA-C₈) was confirmed using ER-XPS. The XPS with SR soft X-ray source detect only the single bilayer structure of the PFA-C₈ component, whereas the XPS with Mg Kα X-ray source detect both the PFA-C₈ component at the outermost surface and PEG component at the interior.

Thermo-responsive liquid marbles can be prepared using poly(N-isopropylacrylamide) powder and Na₂SO₄ aqueous solution, which were transferred to the surface of bulk water containing Na₂SO₄ aqueous solution. They remained stable at room temperature. When the bulk aqueous solution was cooled, the liquid marbles disintegrated because powder wettability increased. Thus, the remote triggering of chemical reactions using liquid marbles can be achieved by cooling.

Laminated film composite was fabricated by stacking the surface-modified poly(ethylene terephthalate) films using the initiated chemical vapor deposition (iCVD) method, with a ultraviolet (UV)-curable methacrylate-polyhedral oligomeric silsesquioxane (POSS) inorganic polymer interlayer binder to develop an alternative glass material. The 11-layered PET film/POSS composites were consolidated by UV exposure, and it increased modulus and maintained transmittance and haze.

STEP Isodiametric design space based deposition of polymeric micro/nanofibers in hierarchical multi-layer assemblies with control on fiber diameter, spacing and orientation.