Original Article in 2023

Radical copolymerization of lithium p-styrenesulfonate (LiSS) was investigated using acrylamide (AAm) as the comonomer in the presence of various salts as additives. The addition of lithium chloride promoted the polymerization reactivity of LiSS, while the addition of lithium bromide and sodium bromide suppressed the copolymerization of LiSS and AAm and completely prevented the spontaneous homopolymerization of AAm. The interactions between lithium cations and functional groups in the monomers and polymers that benefit the copolymerization reactivity is discussed.

Polymer gels containing an iridium complex in their compartmentalized nanodomain structures were designed. Novel Ir-containing vinyl monomers were first synthesized and then incorporated into homogeneously dispersed thermoresponsive nanodomains via living radical polymerization. The product gels exhibited immediate color change by sensing ammonia in a thermoresponsive manner, and catalyzed the N-alkylation reaction. These findings strongly supported the importance of the incorporation of organometallic complexes into the nanodomain of hydrogels for the further development of a novel soft material exhibiting selective molecular recognition abilities and catalytic reactions.

The transparent and flexible photocatalytic films composed of titanium oxide, organophosphonate-modified polysilsesquioxane, and poly(bisphenol A-co-epichlorohydrin) were prepared. The effects of hydroxy group ratio and organic substituent on phosphorus atoms in these films were evaluated by appearance and photocatalytic ability. Film using anchoring layer with APPS-low was formed large cracks, while films with other anchoring layers were formed no cracks. However, all films were formed small cracks after a 10-day durability test. All films showed photodegradation ability of methylene blue, photoinduced hydrophilicity, and photocatalytic bactericidal effects on Escherichia coli.

Two-dimensional sheet-shaped poly(methyl methacrylate) (2d-PMMA) with crosslinking only in the two-dimensional direction was synthesized via planar polymerization of MMA monomer in montmorillonite (MMT) nanolayers by using γ-ray irradiation, and the samples obtained were characterized by size-exclusion chromatography with a multiangle light scattering (SEC-MALS) and atomic force microscopy (AFM). Our results provided experimental proof that the desired sheet-like polymer was attained and the obtained samples were appropriately characterized, augmenting the previous reports.

Statistical structural analysis was conducted for ternary blends of copolymers composed of two monomers chosen from acrylonitrile, α-methylstyrene, and styrene. Blending parameters, such as the composition and blending fraction of the component copolymer, were predicted by regularized regression analysis of ¹H NMR data. Regression models were constructed with the dataset for copolymers and binary blends to predict the blending parameters for ternary blends. The composition and blending fraction were predicted with high accuracies

We propose a method for analyzing the morphology of polymer blends with nanometric resolution using scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopic imaging in the low energy-loss region (5–30 eV). Furthermore, we employed medium-voltage (200 kV) and high-voltage (1000 kV) STEMs at different temperatures to compare the extent of electron-beam damage. This comparison highlighted the utility of the ultra-high voltage electron microscope for suppressing thermal damage and analyzing thicker samples.

Anionic initiator systems for styrene polymerization were prepared via desilylation of benzylsilanes with metal alkoxides. Benzyltrimethylsilyl anions as the anionic polymerization initiators were obtained from benzylsilanes and potassium tert-butoxide at 70 °C in the absence of 18-crown-6. On the other hand, in the presence of 18-crown-6, benzyl anions were obtained at −78 °C. Subsequent addition of the styrene monomer to these initiators yielded polystyrenes. With the addition of 1,1-diphenylethylene (DPE) to the initiator system containing 18-crown-6, the corresponding DPE adduct was obtained.

A novel polymer material PEDOT:DBSA was prepared using oxidative polymerization and was modified by cross-linker GOPS and H₂SO₄-posttreatment. This material exhibits biocompatibility toward cell culture comparable to the glass substrate. The cross-linking process resulted in complete stabilization of PEDOT:DBSA thin film in an aqueous environment, whereas such stabilization was achieved even without high-temperature treatment. The model OECT device proved that the proposed material possesses electrical properties comparable to or even better than other organic mixed conductors used for transistors. This all shows a great potential of PEDOT:DBSA for bioelectronics applications.

Photoresponsive molecular amphiphiles have been incorporated into distinct soft materials to control properties in high temporal and high spatial manners. We demonstrate molecular azobenzene amphiphiles for construction of chiral supramolecular assemblies with excellent photoresponsibility and a high capacity for supramolecular transformation in aqueous media. Supramolecular chiral structures of azobenzene amphiphiles can assemble from microscopic to macroscopic length scales

In our study, a continuous change of tensile strength (26.9–49.5 MPa) and impact strength (4.7–23.2 KJ/m²) of iPP samples is successfully accomplished without the specific catalysts. The high content of γ-crystal with thin lamellar thickness related to the ductility property is also experimentally confirmed. A morphology of the diagram is proposed based on the composition and molded technology.

Here, we introduce a candidate material, water-soluble guanidinylated chitosan (WGCS), for a protein delivery system. WGCS composed of 48.2% guanidinylated chitosan, 20.6% chitosan, and 31.2% chitin units was prepared from low-molecular-weight chitosan (CS). WGCS showed ca. 2.5-fold higher internalization into HeLa cells than CS does. Moreover, we found that WGCS significantly enhanced the internalization of bovine serum albumin in transport medium at pH 7.4.

Cashew nut shell liquid (CNSL) is a natural phenolic compounds that is non-edible biomass. A novel diglycidyl ether (BCNDGE) derived from CNSL was synthesized and used as a building block to formulate an epoxy resin. Epoxy resins were cured from BCNDGE and commercial diglycidyl ether (BPADGE) with acid anhydride hardener. BCNDGE content improved the thermal stability and flexibility of the epoxy compared with commercial BPADGE-based epoxy. Hence, BCNDGE is a promising novel diglycidyl ether candidate with high biomass content to act as an alternative to petroleum-based chemicals for epoxy resins.

The coil-to-globule-to-coil transitions of a zwitterionic polymer, poly(2-[(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonio]acetate) (PCB2), in water, ethanol, and water–ethanol mixed solvents were investigated and compared with those of poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC). PCB2 showed cononsolvency in water–ethanol mixed solvents with specific ethanol volume fractions. PCB2 showed a broader cononsolvency range than PMPC because of its lower association constants of water and ethanol and the marked competition for hydrogen bonding. The zwitterion-specific cononsolvency characteristics were rationalized with the electrostatic potentials and van der Waals energies of the zwitterions.

Supramolecular chiral emergence from achiral molecules is studied using newly designed amphiphilic polypeptides upon self-assembling into nanosheets and vesicles in water. The polypeptide, SL-π-D, contains a hydrophilic poly(Sar) block, two hydrophobic helical blocks, and a π-conjugate block. The helical blocks possess right- and left-handed helices, compensating for helical chirality resulting in an achiral molecule. SL-π-D self-assembled in trifluoroethanol/water solutions into uniform nanosheets and vesicles, with the Cotton effect appearing in the achiral π-conjugate block. Supramolecular chiral emergence intrinsically arises from the molecular structure and is enhanced in vesicular morphology.

Bis(3-aminopropyl)-DDSQ was employed for polymerization with various aromatic dialdehydes to obtain poly(azomethine)s with high double-decker-shaped phenylsubstituted silsesquioxane (DDSQ) contents in the main chain. Introducing the flexible propylene linkers in the DDSQ unit provided flexible and optically transparent free-standing films. Their mechanical properties were highly dependent with the structures of the dialdehyde co-monomers.

The melting temperature of the isothermally crystallized poly(trimethylene terephthalate) (PTT) lamellar stack structure was determined by X-ray measurements. The equilibrium melting temperature of PTT was determined to be 290.5 °C from the relationship between the melting temperature and the lamellar thickness. The temperature dependence of the lamellar thickness below T_c = 173.7 °C suggested crystallization through a mesophase. The temperature dependence of the growth rate was explained by secondary nucleation theory over a wide crystallization temperature range.

We investigated the effect of the hydrophobicity of the side chains of mixed-charge polymers on their interaction with cancer cell membranes. Six pH-responsive mixed-charge polymeric micelles consisting of cationic, anionic, and neutral moieties were created, with differences in hydrophobicity generated by altering the type of anionic monomer and the ratio of the hydrophobic spacer moiety. Evaluation of their affinity for cell membranes revealed that increases in the hydrophobicity and pH-responsive nature led to pH-selective toxicity, which was assumed to be caused by the disruption of cell membrane integrity.

Time-resolved FTIR was used to study the crystallization kinetics of syndiotactic polystyrene. Isothermal crystallization from the melt by cooling and from the glass by heating was used to determine the temperature (T_c) dependence of the crystallization rate (k). Based on the derived k and the crystal growth rates (G) obtained from OM and depolarized light scattering, the density of primary nucleation was readily calculated. The magnitudes of the nucleation densities in the cold-crystallized samples were ~5−6 orders higher than those of the melt-crystallized samples despite the similar k values.

Distannylated dithiazologermole and germaindacenodithiazole were copolymerized with dibrominated benzothiadiazole and di(thiazolyl)benzothiadiazole to produce four new donor-acceptor conjugated copolymers. The optical, electrochemical, and thermal properties of the copolymers were characterized. DFT calculations revealed that these thiazole-containing copolymers possessed lower HOMOs and LUMOs than those of thiophene-based congeners, in accordance with the experimental results. The intramolecular noncovalent S‒N and N‒H bond interactions and the effects of the bridging atom (C or Ge) on the HOMO and LUMO energy levels were also suggested by the DFT calculations.

Catechol-modified alginates (AlgDAs) with various catechol contents were synthesized and examined as adhesive materials. AlgDA exhibited high adhesive strength with mica and moderate adhesive strength with polymer resins, although this adhesiveness was not observed for sodium alginate. AlgDA with a relatively low catechol content exhibited relatively high adhesive strength, unlike other catechol-modified polymer adhesives. AlgDA residues were successfully removed from the used substrates by a simple water washing process. AlgDA is promising as a biobased adhesive material that contributes to a sustainable society.