Prof. Stefano Sacanna
David Wang Auditorium, 3rd floor Dalia Meidan Bldg.
From snowflakes to nanoparticle superlattices, a menagerie of complex structures emerge from simple building blocks attracting each other with Coulombic forces. On the colloidal scale, however, this self-assembly feat is not easily accomplished. Although many colloids bear an innate surface charge, their strong electrostatic attraction is not directly suitable for crystallization. Instead, particles must be finely crafted to serve as self-assembling units. In this talk, I’ll show the robust assembly of crystalline materials from common suspensions of oppositely charged colloids through a generic approach which we refer to as polymer-attenuated Coulombic self-assembly. I will demonstrate that, when particles are held separated at specific distances by a neutral polymer spacer, the attractive overlap between oppositely charged electrical double layers can be systematically tuned, directing particles to disperse, crystallize, or become permanently fixed on demand.