Fumio Sanda

Optically active Schiff base polymers were synthesized from ʟ‐alanine‐ and N ‐methyl‐ʟ‐alanine‐derived diamines with ortho ‐, meta ‐, and para ‐phthalaldehydes. Meta ‐ and para ‐linked NH polymers exhibited intense circular dichroism (CD) signals, indicating chirally fixed conformations, whereas ortho ‐linked and N ‐methylated polymers were CD‐inactive. Dynamic light scattering measurements suggested that only the CD‐active polymers formed folded and/or weakly associated structures in solution. Acid‐catalyzed hydrolysis showed pronounced structure dependence. Ortho ‐linked polymers were resistant to hydrolysis, whereas meta‐ and para‐linked polymers underwent clean depolymerization under mildly acidic conditions. The NH polymers hydrolyzed more slowly than the corresponding N ‐methylated analogs, likely due to reduced molecular mobility associated with conformational fixation. Furthermore, the para ‐linked polymer was successfully depolymerized and repolymerized, demonstrating closed‐loop chemical recyclability.

Naphthalimide-containing polyurethane elastomers showed a reversible fluorescence color change from green to blue upon stretching. Molecular simulations revealed that the mechanochromism originates from changes in naphthalimide aggregation.

Ring-opening metathesis copolymerization of norbornene monomers bearing platinum arylacetylide and 9,10-diphenylanthracene (DPA) moieties afforded polymers that exhibit triplet–triplet annihilation upconversion by the addition of DPA.

We report the preparation of chemically crosslinked alginate gels (ChemAlg _ss ) using cystamine as a disulfide‐containing crosslinker, along with dual crosslinked gels (DualAlg _ss ) by further treating with CaCl ₂ . Gelation occurred when cystamine was used at 5–80 mol%, wherein the highest crosslinking density was achieved at 40 mol%. Rheological studies revealed that the storage modulus of DualAlg _ss was larger than that of ChemAlg _ss , reflecting the enhanced formation of physical crosslinking. Moreover, ChemAlg _ss exhibited reversible sol–gel transitions by the treatment with dithiothreitol ( c = 380 mM) and subsequent addition of 30 wt% of hydrogen peroxide aqueous solution. These findings demonstrate a simple strategy for designing redox‐responsive alginate hydrogels.

Alginate- and κ -carrageenan-supported imidazolidinone catalysts were newly prepared, and their catalytic activities for the Friedel–Crafts alkylation of 1-methylindole with crotonaldehyde were evaluated.

Polymers containing conjugated metal complex moieties in the main/side chains are high-performance materials that combine the catalytic and photoelectric functions of metal complexes with the photoelectric properties of π-conjugated polymers.

Difunctional nitrile N‐oxide monomers were synthesized in situ from vanillin, a useful aromatic biomass. The metal‐free dipolar cycloaddition reactions of the obtained divanillin‐based nitrile N‐oxides and dialkynes were conducted to give π‐conjugated polyisoxazoles P1–P4 with number‐average molecular weights ranging from 3100 to 7400 in 90%–95% yields, which were characterized by size exclusion chromatography (SEC), ¹H NMR, and IR absorption spectroscopy. The obtained polyisoxazoles, especially P3 and P4, exhibited absorption peaks at a longer wavelength region compared with the corresponding monomers, indicating the extension of π‐conjugation. Axial chirality was induced in the biphenyl units of P3 by adding a chiral diamine. All polymers exhibited 10% weight loss temperatures above 307°C, indicating good thermal stability.