Colloidal Lock-and-Key Dimerization Reactions of Hard Annular Sector Particles Controlled by Osmotic Pressure.

摘要: Colloidal annular sectors are a broad class of shapes that offer the interesting possibility dimerization when osmotically compressed to high densities while undergoing Brownian motion in two dimensions (2D). Here, we lithographically create and form stable aqueous dispersion many microscale prismatic 270° sectors, explore their near-equilibrium behavior tilted 2D gravitational column. Near top column where osmotic pressure Π(2D) is low, observe gas-like phase composed almost entirely monomers. However, below surface deeper into higher, reaction zone monomers dimers coexist, followed by an arrested region containing very percentage interpenetrating, lock-and-key racemic mixture positive negative chiralities. We determine particle area fractions as function depth use these obtain system's equation state. In zone, transiently break up, also calculate equilibrium constant K associated with monomer-dimer reaction, which increases exponentially Π(2D). This dependence can be attributed reduction number accessible microstates for they become more tightly compressed.