Step-Growth Polymerization of Inorganic Nanoparticles

Self-organization of nanoparticles is an efficient strategy for producing nanostructures with complex, hierarchical architectures. The past decade has witnessed great progress in nanoparticle self-assembly, yet the quantitative prediction of the architecture of nanoparticle ensembles and of the kinetics of their formation remains a challenge. We report on the marked similarity between the self-assembly of metal nanoparticles and reaction-controlled step-growth polymerization. The nanoparticles act as multifunctional monomer units, which form reversible, noncovalent bonds at specific bond angles and organize themselves into a colloidal polymer. We show that the kinetics and statistics of step-growth polymerization enable a quantitative prediction of the architecture of linear, branched, and cyclic self-assembled nanostructures; their aggregation numbers and size distribution; and the formation of structural isomers. T he focus of nanoscience is gradually shift-ing from the synthesis of individual nano-particles (NPs) to the organization of larger nanostructures. Ensembles of NPs show optical, electronic, and magnetic properties that are determined by collective interactions of indi-vidual NPs (1). To fully understand and exploit these cooperative properties, it is important to achieve control of the structural characteristics of NP ensembles. Self-assembly has emerged as a promising, cost-efficient methodology for gen-erating different types of nanostructures (2–10). In particular, one-dimensional (1D) NP arrays have potential applications in optoelectronics (11–15) and sensing (16, 17). Currently, the lack of mod-els describing the kinetics and statistics of the self-assembly of 1D arrays does not allow the quantitative prediction of their structural features (for instance, the length of NP chains; the degree of branching; or the coexistence of rings, linear chains, and branched structures). Phase diagrams provide useful information on the equilibrium

Duke Scholars

Author Michael Rubinstein Thomas Lord Department of Mechanical Engineering and Materia ...