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逆電荷のドロップが凝結しない
W D Ristenpart1, J C Bird, A Belmonte
1Department of Chemical Engineering and Materials Science, University of California at Davis, 1 Shields Drive, Davis, California 95616, USA. wdristenpart@ucdavis.edu
Nature
|September 18, 2009
まとめ
逆の電荷を持つ液滴は,通常合体する. しかし,臨界電場強度を超えると,これらの滴は接触後に互いに排斥し,反発するように見えます. この発見は,充電液滴を含むプロセスに影響を与えます.
科学分野:
- 流体力学 流体力学
- エレクトロキネティクス (電動力学)
- コロイド科学 コロイド科学
背景:
- 電気場は,ポリマー溶液やコロイド懸浮などの様々な流体系における運動を駆動する.
- 電気的に誘発されたドロップレット運動は,インクジェット印刷,電気スプレーイオン化,およびラボオンチップデバイスに関連しています.
- 隣接する電荷のドロップは,多くのアプリケーションにおいて決定的な現象である,典型的には合体します.
研究 の 目的:
- 電気フィールドにおける対極電荷の液滴の凝結行動を調査する.
- 凝結が阻害される条件を特定する.
- 逆電荷のドロップが常に引き寄せ,結合するという仮定に異議を唱えるために.
主な方法:
- 逆電荷の液滴のペアに制御された電場を適用する.
- ドロップレット相互作用と凝結を直接画像を用いて観察する.
- 滴の間にある半月板橋の形成と安定性を分析する.
主要な成果:
- 反対の電荷を持つドロップは,電場の中で互いに移動する.
- フィールドの強度が低い場合,ドロップは予想どおりに凝結する.
- クリティカルなフィールド強度を超えると,ドロップは接触時に反発し",反発"の行動を示します.
- 暫定的なメニスカスブリッジ形成が観察され,高い電場では不安定であることが判明しました.
結論:
- 反対に電荷を積んだドロップの凝結を防ぐ,臨界の電場強さが存在する.
- 観測された排斥は,強い電場下で一時的なメニスカスブリッジの不安定さによるものである.
- この現象は,デエムルシフィケーションやエレクトロスプレーイオン化などの,電荷液滴を含むプロセスの再評価を必要とします.
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