Kinetics of Ion-Mediated Directed Self-Assembly of One-dimensional Chains of Metal Nanoparticles in Solution

Abstract

The synergistic optical, electronic and chemical properties in metal nanoparticles in close proximity have potential applications in energy, medicine and sustainability. Fundamental studies and application development of spontaneous self-assembly of one dimensional (1D) chains of metal nanoparticles without any external organizing agency have been pursued for over four decades. The spontaneous formation of 1D chains in solution of stabilized spherical nanoparticle driven by emergence of local anisotropy due to dipolar interaction is a trapped non-equilibrium state. Here, the kinetics of this broken symmetry in “directed” self-assembly of spherical particles to form 1D chain is studied. The 1D chain assembly of 10 nm Au particle stabilized by electrostatic repulsion is initiated by adding a small amount of divalent cation salt. A phenomenological model is presented to explain the transition state controlling the kinetics of 1D self-assembly. Combining experimental and simulation studies, the kinetics of the chain growth over time was measured to discover a sharp transition between two growth processes analogous to addition and condensation polymerization.