堅牢なのに塩水中で分解するプラスチック～安価な木材成分から製造できる次世代高分子材料～

2025-12-03 理化学研究所,東京大学

図1 超分子イオン重合によって製造された超分子プラスチックフィルム
木材パルプ由来のカルボキシメチルセルロースナトリウム（CMC）と硫酸グアニジニウムモノマー（P^EIGu）を水中、室温で混合すると、静電相互作用（塩橋）に基づくクロスリンクポリマー（架橋高分子）ネットワークが形成される。この架橋成分を乾燥させると、無色透明で非常に硬いガラス状のプラスチック（^CMCSPフィルム）が得られる。

＜関連情報＞

• https://www.riken.jp/press/2025/20251203_2/index.html
• https://pubs.acs.org/doi/10.1021/jacs.5c16680

超分子イオン重合：広範囲に調整可能な機械的特性を持つセルロース系超分子プラスチック Supramolecular Ionic Polymerization: Cellulose-Based Supramolecular Plastics with Broadly Tunable Mechanical Properties

Zhenghong Chen,Yang Hong,Hiroyuki Inuzuka,Kiichi Mizukami,and Takuzo Aida
Journal of the American Chemical Society  Published: November 19, 2025
DOI:https://doi.org/10.1021/jacs.5c16680

Abstract

Developing mechanically tough and sustainable plastics from renewable resources such as biomass may certainly give a promising solution to the replacement of petroleum-based plastics and eliminate microplastics. Here, we report a cellulose-based supramolecular plastic (^CMCSP) synthesized by supramolecular “ionic” polymerization of carboxymethyl cellulose (CMC) as an oxyanionic monomer and a hyperbranched polyguanidinium ion (^PEIGu) as a cationic monomer. ^CMCSP is mechanically strong but inherently brittle. However, as highlighted in the present paper, we could overcome the brittleness issue by adding (2-hydroxyethyl)trimethylammonium chloride (choline chloride, ChCl) to ^CMCSP. This FDA-approved, biodegradable ionic human nutrient served as a particular plasticizer, enabling broad modulation of stiff, glassy ^CMCSP to a tough, flexible material and further to a soft, elastic material. We demonstrated that plasticized ^CMCSP_ChCl could be processed into a flexible plastic bag, which was mechanically tough but perfectly dissociable in seawater and closed-loop recyclable with electrolytes. Hence, ^CMCSP_ChCl never generates microplastics.