Presentations

優れた抗菌性と界面活性を有する第四級アンモニウム塩型カチオン性界面活性剤は多くの分野で使用されているが、循環型社会構築の観点から、環境調和性、高機能性、生分解性、さらにはリサイクル性が求められる。本報では、第四級アンモニウム塩に生分解性とリサイクル性を付与する目的で、分子内にカーボネート結合を有するジェミニ型カチオン性界面活性剤を設計し、それらのグリーンプロセスによる合成と機能について検討を行った。

Recently, polythioester has attracted attention due to their interesting properties, such as high melting point and heat stability. Synthesis of high molecular weight poly(thio-oxyester) using an enzyme was studied. First, 6-mercapto-1-hexanol and dimethyl sebacate were reacted in n-nonane using lipase CA to produce cyclic(thio-oxyester). A poly(thio-oxyester) having an Mw of about 120,000 was prepared by the ring-opening polymerization of cyclic(thio-oxyester)using lipase CA. A higher melting point was observed compared with the corresponding poly(oxyester). The rate-determining step of the polymerization was determined to be the nucleophilic attack by the thiol, which differs from the corresponding enzymatic polymerization reactions.

Chemical recycling of poly (butylene succinate) (PBS) was studied using a lipase with respect to the ring-size of the oligomer. It was found that PBS was degraded in a dilute toluene solution using lipase CA to produce cyclic oligomers mainly consisting of dimer and trimer. By the ring-opening polymerization of isolated cyclic BS dimer by lipase, PBS with an Mw of 170,000 was produced. On the other hand, PBS with an Mw of 130,000 was produced from isolated cyclic trimer. That is, cyclic dimer produced a higher molecular weight polyester than from cyclic trimer by the ring-opening polymerization. By degradation of PBS using lipase CA, cyclic dimer was obtained in a maximum yield of 70%.

Seven-membered cyclic tetramethylene carbonate was synthesized by the condensation of butane-1,4-diol and diphenyl carbonate in a toluene solution using immobilized lipase from Candida antarctica(lipase CA) as an environmentally benign process. The cyclic tetramethylene carbonate was readily polymerized by lipase CA in bulk to produce poly(tetramethylene carbonate) (PTeMC) with a molecular weight of 103,000. The molecular weight of PTeMC prepared by the ring-opening polymerization of cyclic carbonate was significantly higher than that produced by the direct polycondensation of butane-1,4-diol and diethyl carbonate using lipase CA. It was also found that PTeMC was amorphous as determined by DSC, and the contact angle of the surface of PTeMC was 83ｏ(±1.3ｏ).

Poly(ester-urethane) was synthesized from bio-based amino acid using an enzyme. Thermal and physical properties as well as chemical recyclability and biodegradability of poly(ester-urethane) were evaluated.

Chemical recycling of bio-based polymers such as poly(butylene adipate) and poly(butylene succinate), were studied using an enzyme. Chemically recyclable bio-based polymers were prepared via the ring-opening polymerization of cyclic oligomers which were produced by the condensation of diols and dicarboxylates by lipase in a toluene solution. The cyclic oligomer was readily polymerized by the same lipase in more concentrated solution to produce a high-molecular weight polyester. The produced polyester was readily degraded by lipase to produce cyclic oligomers as the chemical recycling. In this report, the effect of ring-size of cyclic oligomer was studied with respect to the repolymerizability.

Aliphatic polythionoesters were prepared by the one-pot thionoesterification of polycaprolactone, polypentadecanolactone, poly (butylene succinate) and poly (butylene adipate) using diphosphorus pentasulfide and hexamethyldisiloxane. And their physico-chemical properties as well as enzymatic degradabilities and chemical recyclabilities were evaluated.