Research articles

Polyelectrolytes (PEs) with high water uptake prepared from cellulose-type polysaccharides are promising because of their excellent biodegradability. In this work, utilizing a two-step selective oxidation process a new type dicarboxylate nanocrystalline cellulose (DCNC) PE was prepared. Carboxylate units were introduced at the C-2 and C-3 positions of a glucose moiety to ensure the presence of a large number of dissociable electrolytic ions. It was observed that the equilibrium water uptake capacity of the prepared DCNC was almost ten times greater than that of conventional C-6 functionalized monocarboxylated nanocrystalline cellulose.

A binder, poly(2-propenoic acid, 2-methyl-, 3-[(2-aminoethyl) amino]-2-hydroxypropyl ester) (P-HAEAPMA), is synthesized and applied to silicon/graphite anodes in lithium-ion batteries, which exhibits good electrochemical stability. After 305 cycles, a specific capacity of 485.0 mA h g⁻¹ and a capacity retention rate of 74.8% are achieved. Moreover, the discarded electrode with P-HAEAPMA binder can be reused just based on water because the P-HAEAPMA binder is easily soluble in water, and the electrochemical properties of the electrode with reused materials are slightly lower than those of the original electrode.

Poly[oligo(2-ethyl-2-oxazoline) methacrylate] (P[O(Ox)_nMA]) was mixed into a thin film of poly(methyl methacrylate) (PMMA) to construct a bioinert polymer surface in water. Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) revealed that P[O(Ox)_nMA] having nitrogen atoms in the side chains was segregated at the outermost region of the PMMA film in a water environment. The extent of the segregation was dependent on the architecture of P[O(Ox)_nMA] due to the entropic factor, and greater extent was better for the platelet adhesion and activation.

The real-time structural changes of thermoresponsive polymer vesicles upon cooling were investigated by small-angle X-ray scattering and confocal laser scanning microscopy. The disassembly process of the vesicles consists of multiple steps: 1) pore formation, 2) opening and shrinkage of the membrane, and 3) dissolving in the solvent. We also demonstrated that the vesicles can be used as compartments for the controlled release of proteins. This study provides the basis for the mechanism of the disassembly process of thermoresponsive vesicles and a guideline for their use as controlled-release medical devices.

The polymerization of divalent acyl-1,2,4-triazoles and diols/bisphenols afforded a series of aromatic, semiaromatic, and aliphatic polyesters. Compared with polymerization by transesterification, this polymerization proceeded irreversibly at relatively low temperature (<100 °C) without a metal catalyst. The reactivities of acyl-1,2,4-triazoles were thus comparable to acyl chlorides. On the other hand, higher crystallinity and lager masses of acyl-1,2,4-triazole caused technical problems, particularly for the synthesis of polyarylates. Nevertheless, solution polymerization was effective to prepare polyacrylates, particularly which could not be synthesized by interfacial polymerization.

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.

Amphiphilic diblock copolymers (M₉₈E_n) composed of hydrophilic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and hydrophobic poly(2-methoxyethyl acrylate) were synthesized via controlled radical polymerization. M₉₈E_n formed micelles in water, which can encapsulate hydrophobic guest molecules into the core. The micelles did not interact with proteins in an aqueous solution due to the PMPC shells.

Polymeric hydrogen carrier with high thermal stability was prepared by incorporating isopropanol and acetone units into polymers via a facile reaction process. Reversible hydrogen fixing and releasing were achieved with full conversion under mild conditions. Temperature-dependent facile hydrogenation and dehydrogenation cycle that operated at temperatures higher than the boiling points of isopropanol and acetone, in the presence of an iridium complex catalyst, was established by virtue of having these groups as pendants of the vinyl chain, with a compact repeating unit to maximize the mass hydrogen storage density of 2.8 wt%.

In this Note, the heat-proofing and anti-plasticizing nature of poly(ethylene carbonate) by the addition of a defibered plant (DP) is presented. The DP was obtained via simple wet-milling treatment for water-dispersed Japanese cedar. The presented results encourage us to use plants as functional fillers without a special chemical/biological reaction.

The mechanical stretching behavior of poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) was investigated under three different stretching modes and through in situ SAXS analysis. SEBS exhibited smaller hysteresis during cyclic equi-biaxial stretching than that of uniaxial stretching. SAXS measurement revealed that affine deformation occurred in the smaller stretching ratio (λ) region for both uniaxial and equi-biaxial stretching modes and deviation from affine deformation occurred for uniaxial stretching mode at the larger λ region. This is because entangled loops of poly(ethylene-co-butylene) chains serves as cross-linking points when films are stretched under equi-biaxial stretching mode.

Poly(trimethylene carbonate) (PTMC) based polymers were blended with N,N,N-trimethylchitosan (TM-CS). The tensile strength of the chitosan (CS) and TM-CS films blended with PTMC was found to cause brittleness, but a PTMC derivative copolymer bearing carboxylic acid improved the elongation properties of TM-CS. A softer film was obtained for a blend film composed of TM-CS with 25% consisting of an added PTMC derivative copolymer bearing a 10% carboxylic acid moiety on the side chain. This is the first report of the modification of CS using polymers with a PTMC backbone.

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.

We developed a W/O miniemulsion reactor system enabling the preparation of biopolymer nanoparticles and control of their morphologies and inner microstructures. We produced agarose hydrogel nanoparticles (AgarH) by the gelation of agarose in nanodroplets of a W/O miniemulsion. Next, we prepared agarose xerogel nanoparticles (AgarX) by precisely tuning the water evaporation from AgarH. We controlled the morphologies (solid and hollow) and crystal structure of AgarX by changing the pressure and temperature. The resultant AgarX possessed high crystallinity and thereby exhibited water resistance better than AgarH.

Free-standing, tartaric acid cross-linked chitosan thin films doped with magnetically aligned NiO-Co₃O₄ filler were successfully synthesized using facile solution-casting method under externally applied magnetic field. The aligned membranes displayed higher proton conductivity than Nafion-212 when measured by both two-probe and four-probe techniques in zero humid conditions. The membranes also showed excellent thermal, oxidation, and mechanical stability.

A series of aliphatic polycarbonate-based polyurethanes with different content of cyclic structure was synthesized. There were more hydrogen bonds between soft and hard segments formed as the content of cyclic units increased. The mechanical and thermal properties of the environment-friendly polycarbonate-based polyurethanes can be enhanced and controlled by varying the content of the cycloaliphatic structures. These polyurethanes can be considered as high potential materials that can be used in different applications in the future.

Catalytic ester-interchange reactions allow new sequence information to be written statistically into poly(ester-imide) chains based on NDI (1,4,5,8-naphthalenetetracarboxylic diimide) units. Insertion of the cyclic ester cyclopentadecanolide (“exaltolide”) into an NDI-based homopolymer and quantitative sequence exchange between two different homopoly(ester-imide)s are both catalyzed by di-n-butyl tin(IV) oxide. Emerging sequences from these reactions are identified using pyrene-d₁₀ as a “reader molecule” that binds rapidly and reversibly to the NDI residues, and amplifies the separation of ¹H NMR resonances associated with different sequences via cumulative aromatic ring-current shielding.

Our retinal prosthesis, referred to as a dye-coupled film, was developed by chemically coupling photoelectric dyes to the surface of a polyethylene film for restoring retinitis pigmentosa. However, the amount of coupled dye decreased during an implantation test in a monkey’s eye. For improving long-term durability, anion exchange from Br⁻ to PF₆⁻, BF₄⁻, and bis(trifluoromethanesulfonyl)imide (TFSI⁻) was conducted. The long-term durabilities of the dye-coupled film–PF₆⁻, –TFSI⁻, and –BF₄⁻ improved by 637, 215, and 48%, respectively, indicating that the dye-coupled film–PF₆⁻ exhibits the best long-term durability.

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.

A microstructured film was fabricated using the breath figure method, and a slippery surface was achieved by infusing silicone oil onto the film. Among the obtained samples, oil-supported pincushion films (oPCF) most efficiently prevented water droplets and microorganisms from adhering to the surfaces. In addition, the adhesion of E. coli and B. subtilis to oPCF was reduced to 7.1 and 13% of that pertaining to PTFE, respectively. These results suggest that our efficient antifouling substrate can ensure human health and environmental safety without the use of any toxic compounds.

Thermoresponsive degradable copolymers and hydrogels were synthesized by radical copolymerization of 2-methylene-1,3-dioxepane (MDO) and N,N-dimethylacrylamide (DMAAm). These prepared materials showed thermoresponsive property through the balance of hydrophobic MDO and hydrophilic DMAAm in the polymer chain. Under alkaline conditions (pH 11.3), these materials degraded and turned into water-soluble oligomers. In addition, the hydrogels self-degraded in PBS due to the decreased pH of the inner hydrogel. The prepared thermoresponsive degradable hydrogels are expected as stimuli-responsive drug delivery carriers and cell culture scaffolds.