アソシエティブポリマーネットワークにおける拡散のメカニズム: チェーンホッピングの証拠
Peter B Rapp1, Ahmad K Omar1, Bradley R Silverman1
1Division of Chemistry and Chemical Engineering , California Institute of Technology , 1200 East California Boulevard, MC 210-41 , Pasadena , California 91125 , United States.
Journal of the American Chemical Society
|October 2, 2018
まとめ
チェーンホッピングは,アソシエティブなポリマーネットワークにおける拡散を支配する. 新しいモデルは,自己拡散度測定によって検証された,ブリッジ形成に対するエントロピックペナルティに基づいてこの振る舞いを説明します.
科学分野:
- 柔らかい物質の物理
- ポリマー科学
- 材料化学
背景:
- アソシエティブポリマーネットワークは,可逆的なポリマー結合によって形成される一般的な柔らかい材料です.
- チェーンの移動メカニズム (例えば,歩く,ジャンプ) を理解することは極めて重要ですが,定量的な実験データは欠けている.
研究 の 目的:
- 結合性ポリマーネットワークにおける支配的なチェーンホッピングメカニズムに関する実験的証拠を提供すること.
- 鎖移動と結合ダイナミクスにおけるエントロピックペナルティの役割を調査する.
主な方法:
- モデル関連ポリマーの自己拡散性測定を用いた.
- ネットワークの性質に基づいてジャンプチェーンの分数を予測する熱力学モデルを開発した.
主要な成果:
- チェーンホッピングは,ブリッジ形成に対するエントロピックペナルティにより,効果的な拡散を支配することが示された.
- 複数の関連ドメインを持つ鎖の結合強度の低下が観察され,ジャンプが好ましい.
- 分子とネットワークのパラメータを基にホッピング分子を正確に予測します.
結論:
- 局所ネットワークの構造はエントロピー的な罰則を課し,チェーン構成を制限し,歩行をジャンプすることを促進します.
- テレケリックポリマーの結合不対称性は,このジャンプする優位性から生じる.
- 導出された熱力学モデルは,結合ポリマーネットワークのダイナミクスの予測フレームワークを提供します.
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