ポリロタキサンにおけるトポロジカルな制約による長時間のガラス化
Kazuaki Kato1,2, Akihiro Ohara1, Hideaki Yokoyama1
1Department of Advanced Materials Science, Graduate School of Frontier Sciences , The University of Tokyo , 5-1-5 Kashiwanoha , Kashiwa , Chiba 277-8561 , Japan.
Journal of the American Chemical Society
|August 2, 2019
まとめ
ポリロタキサンにおけるトポロジカル制約は,ガラスの移行ダイナミクスを影響する. リングの覆い面を増やすと,機械的なリラクゼーションが延長され,ガラスの移行温度 (Tg) を超えるセグメントの動きが制限されていることが示されます.
科学分野:
- ポリマー科学
- 材料科学
- 物理化学
背景:
- ポリロタキサンは,独特のトポロジカル構造を持つ超分子ポリマーである.
- グラストランジション (Tg) は,ポリマーの動力学と材料性能に影響を与える重要な特性です.
- ポリロタキサンにおけるTgの理解は,高度な材料の設計に不可欠である.
研究 の 目的:
- ポリロタキサンのガラス化ダイナミクスに対するトポロジカル制約の影響を調査する.
- リングカバーの度合いが リラックス行動にどう影響するかを体系的に研究する.
- 分子運動とトポロジック制約の関係を解明する.
主な方法:
- ポリマーとスレッドリング分子の比率が異なるポリロタキサンの合成
- グラス変換温度 (Tg) を測定するための微分熱分析 (DTA)
- ダイナミックな行動を分析するための機械的なリラックス測定.
主要な成果:
- 同様のTg値は,DTAによる異なるカバレッジのポリロタキサンで観察されました.
- メカニカル・リラクゼーション時間は,リングの覆い範囲が大きくなるにつれて,著しく増加した.
- 2段階のリラクゼーションプロセスが生まれ,カバーに依存するより遅いコンポーネントがあります.
- セグメンタルモーションは,Tgよりかなり高い温度で凍結し,カバー度とともに増加することが判明した.
結論:
- ポリロタキサンにおけるトポロジカル制約は,ガラスの移行ダイナミクスを著しく変化させる.
- リングはTgで従来の相互作用から解放されるが,その協同的転移運動はスレッドポリマーによって妨げられる.
- リングの覆いが増加すると,より高い温度でセグメンタル運動が制限され,材料の特性に影響されます.
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