Materials Science of Foldamers: Fine Control of Folding Structures and Their Use as Functional Soft Materials

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H04880
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Polymer chemistry
• Research Institution: Kyoto University
• Principal Investigator: SAKURAI Tsuneaki 京都大学, 工学研究科, 助教 (50632907)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: フォルダマー / 共役高分子 / 共役構造 / 折り畳み / 積層 / 結晶化 / 柔軟鎖

Outline of Final Research Achievements

Foldamer is an oligomer or polymer adopting a specific compact conformation, the structures of which are stabilized by a collection of noncovalent interactions among monomer units. The change of physical properties associated with the structural changes of foldamers in the solid state are targeted in this study. One of the designs of the foldamers employs the alternating polymers of conjugated molecules and flexible linkers, while the other consists of conjugated oligomers (oligothiophene) and rotating hinges (ferrocene). These foldamers were synthesized and revealed to show folding behaviors in solution, where the electronic interactions of adjacent conjugated segments were analyzed by absorption and fluorescence spectroscopy. In the dropcast films, folding structures were partly observed, but the purity of the structures in whole the area was low. Meanwhile, the dimer model compounds yielded perfect crystalline closed-form structures in the solid state.

Free Research Field

超分子化学

Academic Significance and Societal Importance of the Research Achievements

共役高分子や共役低分子骨格の積層状態を、柔軟鎖あるいは回転関節と化学結合で連結することで、制御することが可能ということが示された。また、積層状態の構造周期性（結晶性）が電子状態に与える影響を実験的に明らかにした。これらのことから、刺激応答によって電気伝導性が変化するフレキシブルな素材を開発するにあたり重要な知見を得ることができた。分子という最小単位から構築することで、材料機能を変調させることができるという意味で、将来の機能性材料設計につながることが期待される。