%0 Book Section %1 statphys23_0892 %A Oettel, M. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K capillarity casimir colloids effect electrostatics interfaces statphys23 topic-7 %T Colloidal interactions at fluid interfaces: electrostatics, capillarity and fluctuations %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=892 %X The effective interaction of colloids trapped at fluid interfaces exhibit qualitatively new features when compared to the ones in colloidal bulk solutions. First, electrostatic interactions which are exponentially screened in ionic solvents become longer-ranged and dipole-like at interfaces between water and a nonpolar medium (usually taken to be air or oil). We show (within Poisson-Boltzmann theory) that charge renormalization makes the effective electrostatic repulsion weakly dependent on the surface charge density on the water side and independent on the salt concentration in the high charge density limit 1. This is in stark contrast to expectations from linear Debye-Hueckel theory which has been used frequently to interpret experimental results. Secondly, capillary attractions mediated by deformations of the interface vary logarithmically with the intercolloidal distance whenever external forces act on the colloids and with a power-law for mechanically isolated systems. For charged colloids, the capillary attractions asymptotically vary dipole-like as do the repulsive electrostatic forces. Only for specific circumstances (ultrapure water, similar colloid radius and water screening length) a secondary minimum in the effective potential may arise 2. Thirdly, capillary wave fluctuations lead to a fluctuation induced force between the colloids (thermal Casimir effect) whose range strongly depends on the boundary conditions determining the three-phase contact line. For fixed colloids and pinned contact lines, we obtain fluctuation potentials which again vary logarithmically, whereas for freely floating colloids and unpinned contact lines the fluctuation interaction is short-ranged and attractive similar to the van-der-Waals interaction 3. 1) D. Frydel, S. Dietrich, and M. Oettel, submitted.\\ 2) M. Oettel, A. Dominguez, and S. Dietrich, JPCM 17, L337 (2005).\\ 3) H. Lehle, M. Oettel, and S. Dietrich, EPL 75, 174 (2006).

@incollection{statphys23_0892, abstract = {The effective interaction of colloids trapped at fluid interfaces exhibit qualitatively new features when compared to the ones in colloidal bulk solutions. First, electrostatic interactions which are exponentially screened in ionic solvents become longer-ranged and dipole-like at interfaces between water and a nonpolar medium (usually taken to be air or oil). We show (within Poisson-Boltzmann theory) that charge renormalization makes the effective electrostatic repulsion weakly dependent on the surface charge density on the water side and independent on the salt concentration in the high charge density limit [1]. This is in stark contrast to expectations from linear Debye-Hueckel theory which has been used frequently to interpret experimental results. Secondly, capillary attractions mediated by deformations of the interface vary logarithmically with the intercolloidal distance whenever external forces act on the colloids and with a power-law for mechanically isolated systems. For charged colloids, the capillary attractions asymptotically vary dipole-like as do the repulsive electrostatic forces. Only for specific circumstances (ultrapure water, similar colloid radius and water screening length) a secondary minimum in the effective potential may arise [2]. Thirdly, capillary wave fluctuations lead to a fluctuation induced force between the colloids (thermal Casimir effect) whose range strongly depends on the boundary conditions determining the three-phase contact line. For fixed colloids and pinned contact lines, we obtain fluctuation potentials which again vary logarithmically, whereas for freely floating colloids and unpinned contact lines the fluctuation interaction is short-ranged and attractive similar to the van-der-Waals interaction [3]. 1) D. Frydel, S. Dietrich, and M. Oettel, submitted.\\ 2) M. Oettel, A. Dominguez, and S. Dietrich, JPCM 17, L337 (2005).\\ 3) H. Lehle, M. Oettel, and S. Dietrich, EPL 75, 174 (2006).}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Oettel, M.}, biburl = {https://www.bibsonomy.org/bibtex/2d8605f8800d8ae611304d980ed22eaa2/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {d30b03a57350e936e79b3c30a16c02c4}, intrahash = {d8605f8800d8ae611304d980ed22eaa2}, keywords = {capillarity casimir colloids effect electrostatics interfaces statphys23 topic-7}, month = {9-13 July}, timestamp = {2007-06-20T10:16:32.000+0200}, title = {Colloidal interactions at fluid interfaces: electrostatics, capillarity and fluctuations}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=892}, year = 2007 }