화학공학소재연구정보센터
Thin Solid Films, Vol.460, No.1-2, 274-278, 2004
Transition from split streamlines to dip-coating during Langmuir-Blodgett film deposition
Mono-molecular films of arachidic acid were deposited on glass slides using the Langmuir-Blodgett (LB) technique. The liquid subphases were dilute solutions of ZnSO4 at different pH. Glass slides were treated to create contact angles (theta) ranging from approximately 15degrees for clean glass slides, to contact angles greater than 120degrees for slides treated with ferric stearate. Intermediate contact angles were created by immersing slides in solutions of Sigmacote((R)) of varying concentration. Very small contact angles, theta approximate to 0degrees were obtained with clean glass slides at high pH values. LB deposition data and transfer ratios (TR) were recorded for upstroke and down-stroke operation. During upstroke, TR increase with decreasing contact angles reaching a maximum TR close to 100% when the receding contact angle is approximately 15-20degrees. This is typical of the split-ejection flow pattern found during up-stroke. For very small contact angles, i.e. less than 10degrees, TR suddenly become zero indicating a transition to a dip-coating flow pattern. During down-stroke operation, TR is zero or negative for small contact angles, reaching a maximum TR approximately 100% for contact angles larger than 120degrees. (C) 2004 Elsevier B.V. All rights reserved.