8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.103Crystallization of charged colloids: shape mattersEthayaraja Mani, 1 Peter Bolhuis, 1 Wolfgang Lechner, 1 and Willem Kegel 21 University of Amsterdam, Postbus 94157, 1090 GE, Amsterdam, Netherlands2 Utrecht University, Utrecht, NetherlandsCrystallization of colloids that interact via very short-ranged attractive potentials (depletion attraction)is known to follow a two-step mechanism: the formation of a dense liquid droplet andsubsequent crystallization within the droplet. Nevertheless, colloids are often charged (weakly orhighly), and this long-range Coulombic repulsive interaction coupled with short-range attractionmay have interesting consequences in the pathway of crystallization and gelation. It has been previouslyknown that a variety of mesophases emerge depending upon the range and strength of thecompeting interactions. Although classical nucleation theory suggests that the nucleus should bespherical, the competition between attractive and repulsive interactions may lead to non-spherical(one or two dimensional) nucleus. We perform molecular simulations to observe this unique pathwayof crystallization, where we find that at low volume fractions of colloids (< 0.05), string likenucleus is observed. The study implies that we might have to develop theories on nucleation whereshape of the nucleus is also an important variable other than surface tension and supersaturation.103