Published papers

Novel gemini-type cationics containing carbonate linkages as biodegradable and chemically recyclable segments were designed and synthesized by a green process. The carbonate linkages were introduced into only the hydrophobic moiety or in both the hydrophobic and linker moieties of gemini-type cationics. They showed higher surface activities, such as a low critical micelle concentration value, a surface tension lowering, and a high adsorption efficiency, when compared to the corresponding single-type cationics. Also, the gemini-type cationics containing carbonate linkages in both the hydrophobic and the linker moieties showed stronger antimicrobial activities when compared to those only in the hydrophobic moiety. It was found that some gemini-type cationics containing carbonate linkages showed higher biodegradability compared to the conventional gemini-type cationics. The biodegradability of the gemini-type cationics decreased when a carbonate linkage was introduced into the hydrophobic moiety rather than the linker moiety. However, some gemini-type cationics containing carbonate linkages both in the hydrophobic and linker moieties showed ready biodegradability. The gemini-type cationics containing carbonate linkages in the hydrophobic moiety showed chemical recyclability by a lipase (E.C. 3.1.1.3).

High-molecular-weight poly(tetramethylene carbonate) (PTeMC) and poly(hexamethylene carbonate) (PHMC) were prepared by the lipase-catalyzed polymerization of butane-1,4-diol or hexane-1,6-diol and diphenyl carbonate via the formation of a cyclic dimer by a green process. Cyclic carbonate dimers were prepared by the lipase-catalyzed condensation of diphenyl carbonate with butane-1,4-diol or hexane-1,6-diol in dilute toluene solution using an immobilized lipase from Candida antarctica, and was followed by the ring-opening polymerization of the cyclic dimer in bulk with the same lipase to produce PTeMC with Mw = 119000 g•mol-1 and PHMC with Mw = 399000 g•mol-1, respectively. Additionally, enzymatic polymerization of cyclic carbonate dimer was analyzed with respect to the Km and Vmax for the lipase.

Novel polycarboxylate-type anionic surfactants and gemini-type cationic surfactants having biodegradability and chemical recyclability were designed and synthesized as a green and sustainable surfactant. Their physicochemical properties, such as surfactant properties and calcium sequestration capacities, and biodegradability were evaluated.

Gemini-type cationic surfactants containing carbonate linkages as biodegradable and chemically recyclable segments, consisting of two long-chain alkyl groups, two quaternary ammonium groups and a linker moiety, were designed and synthesized as novel green and sustainable cationics with improved physicochemical and biological activities. The gemini-type cationics containing a carbonate linkage showed lower critical micelle concentration values compared to the corresponding singletype cationics. Also, the gemini-type cationics containing a carbonate linkage in the linker moiety showed strong antimicrobial activities. The biodegradability of the gemini- type cationics was significantly improved when a carbonate linkage was introduced into the linker moiety. The maximum biochemical oxygen demand-biodegradability of the gemini-type cationics containing a carbonate linkage in the linker moiety exceeded 70% after a 28-day incubation. Furthermore, the gemini-type cationics containing both a carbonate linkage and an n-dodecyl group showed a chemical recyclability using a lipase (E.C. 3.1.1.3).

一連の生体内分解性トリブロックコポリマーPTMC-b-PECA-b-PTMCを化学的方法と―リパーゼを用いた酵素合成により調製した。得られたブロックコポリマーについて種々のｐＨの緩衝液中での分解性の評価をおこなった。また非依存性コントロールリリーズのためのミセル形成能について検討を行った。