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2023 Fiscal Year Final Research Report

Flapping Molecules for Local Force / Local Viscosity Imaging with Ultra-low Threshold

Research Project

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Project/Area Number 21H01917
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Review Section Basic Section 33010:Structural organic chemistry and physical organic chemistry-related
Research InstitutionKyoto University

Principal Investigator

SAITO Shohei  京都大学, 理学研究科, 准教授 (30580071)

Co-Investigator(Kenkyū-buntansha) 佐藤 良勝  名古屋大学, トランスフォーマティブ生命分子研究所, 特任准教授 (30414014)
Project Period (FY) 2021-04-01 – 2024-03-31
Keywordsフォースプローブ / 材料イメージング / ソフトマテリアル / メカノケミストリー / 応力集中 / ゲル / エラストマー / FLAP
Outline of Final Research Achievements

A ratiometric fluorescent force probe (FLAP) with a response threshold of about 100 pN, ideal for polymer physics research, has been developed. By controlling where FLAP is chemically doped, we showed that local stress is more concentrated at the cross-linking sites than at the main chains in cross-linked polymers prior to fracture, making them more likely to be the starting points for fracture. The non-uniform stress distribution was quantitatively tracked using fluorescence imaging for elastomer stretching and polymer gel compression. We also pioneered a method of optically tracking the state of 'strain-induced crystallization', which contributes to the toughening of polymeric materials, and showed that stretching and crystallization of molecular chains occur stepwise rather than simultaneously. New insights into soft matter physics was developed by using FLAP as an environmental response probe, monitoring the local force, the local viscosity, and the single polymer free volume.

Free Research Field

液晶・高分子化学、光化学、構造有機化学

Academic Significance and Societal Importance of the Research Achievements

数pNの力の観測を狙った「FRET型フォースプローブ」を扱うメカノバイオロジーと、共有結合の開裂に200 pN以上の力を必要とする「メカノフォア 」を扱う高分子メカノケミストリーは、同じ「力を視る科学」でありながら、10年間に渡って2つの分野が交差しなかった。その理由は、扱っている上記の蛍光システムが応答する力の閾値が全く異なるためである。一方で、分子鎖の破壊を伴わない絡まった分子鎖の変形を扱う高分子物理では、共有結合の切断よりも低く、なおかつ熱揺らぎを十分に上回る応答閾値をもつ新たなフォースプローブが必要であった。本研究では高分子物理の追跡に最適なプローブを開発し、実際に新知見を開拓できた。

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Published: 2025-01-30  

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