COLL 105 |
| Jaime Ruiz-Garcia1, Ruben D. Cadena-Nava1, Jose L. Cuellar-Camacho1, Emmanuel A. Vázquez-Martínez1, and Miguel A. Valdez-Covarrubias2. (1) Instituto de Fisica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi, Mexico, (2) Departamento de Fisica, Universidad de Sonora, Rosales y Transversal, 83000 Hermosillo, Sonora, Mexico, Rosales y Transversal, 83000 Hermosillo, Sonora, Mexico |
| We report AFM observations of heterogeneous dewetting of the monolayer of collapsed Langmuir-Blodgett films of fatty acids transferred on mica. A new dewetting mechanism is reported where the crystallites act as nucleation centers. Formation of dewetting rings and fingers is observed where the material moves from the edge of the rings or fingers towards the nucleation center, in contrast to typical heterogeneous dewetting. The growth of the dewetting ring follows a power law with time, which is consistent with a diffusion mechanism for the mass transport. After the monolayer has disappeared, Ostwald ripening takes place and the bigger crystallites continue to grow at the expense of the smaller ones. In the case of dewetting with finger formation, Ostwald ripening seems to be present at all times. However, as a mechanism for crystal growth into the third-dimension, it is observed fingers made of molecules climbing the crystallite walls to the top. |
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Symposium in Memory of Arthur W. Adamson
8:30 AM-11:50 AM, Monday, March 29, 2004 Marriott -- Orange County 4, Oral
Division of Colloid and Surface Chemistry |