Summary: 2D Crystallization of Latex Particles in Wetting Films on Solid Substrates
- We have directly observed by optical microscopy the dynamics of 2D ordering of micrometer-sized latex spheres onto a horizontal glass substrate.
- By variation of the electrolyte concentration, the charge of the particles, and their volume fraction, it is proven that neither the electrostatic repulsion nor the van der Waals attraction between the particles are responsible for the formation of two-dimensional crystals.
- We have revealed that the main factor governing the ordering is the convective transport of particles toward the ordered region. The initial formation of nuclei may also be enhanced by attractive capillary forces (due to the menisci formed around the particles).
- Once the role of water evaporation rate, film thickness and menuscus shape have been understood, we were able to design an advanced cell, where these parameters were controlled and modified to obtain the desired results.
- The cell for controlled 2D assembly has been used to obtain large, well-ordered monolayers or multilayers (bilayers, trilayers, etc.). It was shown that the obtained structures possess rudimentary photonic crystal properties.
N.D. Denkov, O.D. Velev, P.A. Kralchevsky, I.B. Ivanov, H. Yoshimura and K. Nagayama, "Dynamics of Two-Dimensional Crystallization", Nature, 361, 26 (1993).
O.D. Velev, N.D. Denkov, P.A. Kralchevsky, I.B. Ivanov, H. Yoshimura and K. Nagayama, "Mechanism of Formation of Two-Dimensional Crystals from Latex Particles on Substrata", Progr. Colloid Polym. Sci, 93, 366 (1993).
N.D. Denkov, O.D. Velev, P.A. Kralchevsky, I.B. Ivanov, H. Yoshimura and K. Nagayama, "Mechanism of Formation of Two-Dimensional Crystals from Latex Particles on Substrata", Langmuir, 8, 3183 (1992).
O.D. Velev and N.D. Denkov, unpublished results (1993).
© Copyright O. D. Velev 1998