Presentations

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 a lipase (Novozym 435) to produce cyclic oligomers mainly consisting of dimer and trimer. The cyclic dimer produced a higher molecular weight polyester than cyclic trimer by the ring-opening polymerization. And differences between cyclic dimer and trimer on the ring-opening polymerization were analyzed. The cyclic dimer was exclusively obtained by sublimation under reduced pressure.

Poly(diester-urethane) (PDEU) was prepared by the lipase-catalyzed polymerization of diethyl adipate and urethanediol which was prepared by the reaction of ethylene carbonate and amino alcohol. Also, poly(ester-urethane) (PEU) was prepared by the polymerization of hydroxyl carboxylic acid containing urethane linkage. Their polymerization behavior, mechanical properties, chemical recyclabilities and biodegradabilities were studied and compared with respect to the molecular structure.

The enzymatic ring-opening polymerization (ROP) behavior of cyclic thioester was studied and compared with that of cyclic oxyester. It was found that the cyclic oxyester polymerized significantly faster than the cyclic thioester by the lipase. A living nature of the polymerization was observed for the ROP of cyclic thioester, and the rate-determining step was determined to be the deacylation of the enzyme-activated monomer by the propagating thiol chain.

Cyclic oligo(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 catalyst. The cyclic oligo(tetramethylene carbonate) was readily polymerized by lipase CA in bulk to produce poly(tetramethylene carbonate) (PTeMC) with a molecular weight of 119,000. When the conversion was exceeded about 90 %, the degradation reaction was more pronounced than the propagation reaction, and the molecular weight of the polymer was gradually decreased. It was also found that PTeMC was amorphous as determined by DSC, and the contact angle of the PTeMC film was 83ｏ(±1.3ｏ). Sufficient cell viability and cell attachment of the PTeMC film were demonstrated

The poly(L-lactic acid) (PLLA)-based polymer blend, PLLA/polyethylene (PE), into repolymerizable oligomer was carried out using montmorillonite K5 (MK5) with the objective of developing a selective chemical recycling process. The PLLA in the PLLA/PE polymer blend was selectively degraded by MK5 in a toluene solution at 100 °C for 1 h to produce the LA oligomer (OLLA) having a molecular weight of a few hundreds. The PE remained unchanged by MK5 and was quantitatively separated by the reprecipitation method. The OLLA was repolymerized using a conventional chemical catalyst to produce a high-molecular weight PLLA.

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.

アニオン性界面活性剤は優れた機能を発揮することから現在最も広く使用されている。しかし、多価金属イオンと不溶性の塩を形成し、洗浄力が著しく低下することが知られている。さらに、環境問題から界面活性剤は優れた生分解性とバイオベース由来原料の使用が求められる。これまでに著者らは、フマル酸オリゴマーが良好な金属イオン封鎖能と生分解性を有することを報告した。そこで、本報ではフマル酸オリゴマーを親水基に用い、長鎖アルキル基を導入することにより、金属イオン封鎖能と生分解性を併せ持つ界面活性剤を、グリーンなプロセスにより得た。さらに、得られた界面活性剤の界面活性能や金属イオン封鎖能といった機能及び生分解性について評価を行った。

プラスチックは優れた利便性から急速な発展を遂げ、金属材料やセラミックスとともに欠くことの出来ない材料となっている。その反面、廃プラスチックの処理、石油資源の枯渇やCO2濃度増大などの問題が顕在化し、生分解性プラスチックの開発や植物資源を利用した素材開発が強く求められるようになっている。本報では生分解性を併せ持つエラストマー素材を指向し、種子油より得られる12-ヒドロキシステアリン酸(12HS)および12-ヒドロキシドデカン酸(12HD)を原料に共重合ポリエステルを合成し、その特性について検討を行った。