Research articles

The first ultrasoft aqueous lithium-ion batteries with coaxial fiber structures were fabricated with an all-hydrogel design. The all-hydrogel fiber aqueous Li-ion battery exhibited a high specific discharge capacity of 84.8 mAh·g⁻¹ and superior cycling behavior and rate capacity performance. A low Young’s modulus (e.g., 445 kPa) for the battery was achieved by making it entirely from hydrogels, which ensured mechanical compatibility with biological tissues.

Viscoelastic properties of comb-shaped ring (RC) polystyrenes with different branch chain lengths were investigated. Even for the RC sample with short branches, a plateau of the dynamic modulus G^*(ω) was observed, suggesting the intermolecular branch chain entanglement occurred. In the region between the plateau and terminal regions, G^*(ω) was observed with a weaker angular frequency dependence than the terminal relaxation. The G^*(ω) data were analyzed with two models: the comb-Rouse model, in which the structures of RC molecules are taken into account by graph theory, and the Milner-McLeish model for entangled star-shaped polymers.

The liquid-phase exfoliation of graphite is mass-producible and cost-effective method of graphene production. Polymers can be employed as dispersants to facilitate the exfoliation of graphite in organic solvents. We synthesized methacrylate polymers with various monomer ratios and molecular weights and investigated the efficient acquisition of graphene from graphite. Graphene with a uniform thickness was obtained when graphite was exfoliated using an optimized polymer dispersant.

Covalent and hydrogen-bonding architectures were designed in polyisoprene (PI)-based rubber containing the conjugated poly[2,7-(9,9-dioctylfluorene)] (PF) to enable elastic and luminescent behavior with spontaneous healing features.

The crystalline phase and phase transition behavior of an optically transparent film of star-shaped (heptaisobutyl-T₈-silsesquioxy)propyl-substituted octadimethylsiloxy-Q₈-silsesquioxane (star-POSS) were studied by DSC and WAXS measurements. This star-POSS exhibited a crystalline phase with a hexagonal system at room temperature and underwent melting above the melting temperature (T_m). The specimens underwent recrystallization even at temperature above T_m, resulting in the same hexagonal system with slightly larger a- and c-axis lengths. The amorphous state of the surrounding isobutyl substituents on the T₈-cage framework provides an optically transparent film.

We report the nonradiative decay dynamics of charge transfer (CT) states generated in nonfullerene-acceptor-based polymer solar cells. The nonradiative decay rate constants k_nr decreased with an increase in the efficiency for dissociation of CT states into free carriers, indicating that nonradiative decay of CT states can be mitigated by increasing the delocalization of the CT state wave function.

Asymmetric combinations of chiral 2-hydroxyalkanoic acid (2HAA)-based random copolymers with monomer compositions of approximately 50/50, which can form stereocomplex (SC) crystallites, are reported. The copolymer combinations were l-configured individually crystallizable poly(l-lactic acid-co-l-2-hydroxybutanoic acid) or poly(l-2-hydroxybutanoic acid-co-l-2-hydroxy-3-methylbutanoic acid) and d-configured individually noncrystallizable poly(d-lactic acid-co-d-2-hydroxy-3-methylbutanoic acid). This study strongly suggests that SC crystallization occurred when the common monomer units were incorporated into both l- and d-configured 2HAA-based random copolymers. SC crystallization of new types of asymmetric combinations is expected to diversify the attainable properties and biodegradation behavior of chiral 2HAA-based polymer materials.

Hetero-telechelic poly(ethylene glycol)s that contain a hydroxy group and a maleimide-furan adduct their α and ω ends, respectively, were isolated as a novel type of hetero-telechelic polymers (HTPs) via the post-modification of commercially available hydroxy-terminated PEGs with furan-protected p-maleimidophenyl isocyanate and subsequent purification with reversed-phase column chromatography at critical conditions.

We report a thermally cross-linkable fluorescent polymer and its assembly to insoluble microbeads by hydrothermal annealing. A novel fluorene-based poly(triarylamine) bearing crosslinkable styryl groups on a fluorene unit is newly designed and synthesized by a Pd-catalyzed amination reaction. The polymer self-assembles into spherical microparticles and becomes insoluble to organic solvents by hydrothermal crosslinking without losing the spherical morphology. Mixing of the polymer with polystyrene enhances the photoluminescence quantum yield by suppressing the aggregation induced quenching and induces a spectral shift of the emission band to green and red after annealing.

The addition of rGO affected the molecular and crystalline structures of electrospun PLLA scaffolds, leading to the enhanced piezoresponse. An increase of rGO content up to 1 wt% resulted in the increased number of polar C=O functional groups at the surface of fibers and degree of crystallinity of scaffolds. The maximum increase of the effective local lateral piezoresponse (13.9 pm/V) was achieved for 0.2 wt% rGO doping, which is explained by the presence of the shear piezoelectric α-phase (P2₁2₁2₁) in uniaxially oriented PLLA fibers and C=O bond rotation in the polymer chains.

Tetrazine based one-dimensional organic polymers have been investigated as sensing materials for room-temperature sensing of NO₂ gas. The well-defined N-heteroatom functionalization within the polymer’s backbone promotes strong hydrogen-bonding interactions with the analyte and detects various concentrations of NO₂ (25–150 ppm). The sensing was also highly selective towards NO₂ over other tested analytes such as NH₃, EtOH, MeOH, Acetone, 2-nitro toluene, and humidity.

Multiarmed cyclosiloxanes bearing terminal amine groups (D_n^A, n = 4, 5) were obtained via a photocatalytic thiol-ene reaction, with regioselectivities of β-adducts as high as 93% irrespective of the repeating unit number in the cyclosiloxane rings. Ketoenamine-linked hybrid networks using D₄^A and D₅^A as the starting monomers were successfully synthesized via a mild Schiff base reaction with 2,4,6-triformylphloroglucinol and demonstrated high thermal stability and the formation of nanoparticle assemblies.

Postfunctionalization of aromatic C – H bonds at the main chains of π-conjugated polymers (CPs) is ideal for tuning various functionalities of precursor CPs. In this study, we investigated the electrochemical C – H phosphonylation of the main chain of poly(3-hexylthiophene) (P3HT). Anodic phosphonylation of P3HT was successfully achieved using trialkyl phosphite as an electrically neutral nucleophile in the presence of nonnucleophilic dopants. The chemical structures and the optoelectronic properties of phosphonylated P3HT were characterized. The introduction of phosphonate moieties into the main chain of CPs is potentially useful for improving their processibilities and imparting sensing abilities to them.

Cationic block copolymers consisting of quaternized pyridinium salt and hydrophobic acrylate segments were synthesized and their basic properties as ink dispersants were evaluated. Among all polymers, the copolymer of 4-vinylpyridine and butyl acrylate shows the best properties in rheology and dispersion stability. However, further optimization of molecular design is necessary to achieve suitable redispersion properties as ink dispersants. Through this study, we demonstrated the potential of cationic block copolymers as ink dispersants and the issues that need to be improved for better ink performance.

Using interfacial-sensitive sum-frequency generation (SFG) spectroscopy, it was found that incorporation of bulky and polar maleic anhydride (MA) into polystyrene (PSt) chains in an alternating manner, forming an alternating copolymer of P(St-alt-MA), led to reductions in π-π and dipolar interactions at the air interface relative to those in the bulk and thus greater T_g confinement effect for the alternating copolymer. The results demonstrate the crucial impacts of interfacial interactions on polymer dynamics under confinement.

Nanosized keratin particles (Ker-DODAC) were prepared via the assembly of keratin chains with the aid of a cationic surfactant. The obtained nanoparticles (Ker-DODACss) possessed a hydrophobic core composed of surfactants. To modify its internal environment, cholesterol was loaded to nanoparticles. The obtained nanoparticles (Ker-DODACss-Chol) showed retention and release of payloads in response to multiple stimuli. Also, lipophilic antioxidants, α-tocopherol, was loaded to Ker-DODACss-Chol to prevent α-tocopherol from an oxidative degradation and to preserve the antioxidant activity.

Supramolecular nylon-based materials exhibited changes in their Young’s moduli and underwent bending upon irradiation with UV light as a result of isomerization in 1:2 complexes of γ-cyclodextrin and azobenzene. The photoisomerization of azobenzenes led to photoresponsive actuation of the supramolecular materials. The movable cross-links contributed to the mechanical toughness and photoresponsive actuation of these materials. Shape restoration of the nylon-based materials resulted in an extraordinarily high work efficiency.

The results of comprehensive research on the thermal behavior, molecular and crystalline structures of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-HV) films of different thicknesses, their molecular weights (Mw) and 3-hydroxyvalerate (3-HV) contents are reported. The film thickness affects the PHB film crystalline structure and crystallinity. A decrease in M_w leads to a smaller number of piezoactive domains in PHB films. The addition of HV significantly reduces the crystallinity and piezoresponse of PHB films. A decrease in M_w results in the increased crystallinity of PHB-HV films.

An approach inspired by biomineralization has allowed us to develop various organic/inorganic hybrid materials with environmental benignity. In the present study, we have achieved the orientation control of zinc hydroxide carbonate (ZHC) thin-film crystals through the chemical structures and morphologies of the templates. After the thermal treatment of the ZHC thin films, the crystal orientations of the resultant zinc oxide (ZnO) thin films are maintained. The effects of the thickness and annealing time for the polymer templates on the formation of ZnO thin films have been examined.

Mannich-type polycondensation of diamines, bisphenols and PF was conducted in CHCl₃, CHCl₃/triethylamine, and CHCl₃/triethanolamine, respectively. The products were greatly affected by the solvents used. Owing to the combination of alkalinity and solvation effect of triethanolamine, CHCl₃/triethanolamine was preferable for Mannich-type polycondensation which gave main-chain benzoxazines possessing M_n up to 10,000, oxazine content >80.0% and yield >96.0%.