Size-Dependent Electrostatic Chain Growth of pH-Sensitive Hairy Nanoparticles

摘要

Herein, we demonstrate that stepwise tuning of the environmental pH value can guide the reversible self-assembly of gold nanoparticles (Au NPs) coated with pH-responsive polymer brushes into linear chains. The lengths of the as-prepared NP chains are determined by the environmental pH value. The lengths of chains derived from differently sized NPs at a given pH value are almost identical, whereas the number of NPs per chain is inversely proportional to the NP size. Stepwise tuning of the pH value also enables the integration of differently sized NP chains into composite chains: mesoscopic analogues of block copolymers. In these composite chains, the coupling configurations are strongly dictated by the large/small NP size ratio. NP self-assembly provides an experimentally accessible playground for the detailed study of the association processes of atoms, ions, and molecules, such as the glass transition, crystallization, and condensation polymerization. It also promises an unprecedented approach to the creation of new advanced materials with unusual collective physicochemical properties programmed by the spatial configurations of neighboring NPs For example, inorganic NP chains can exhibit polymer-like properties with respect to their elasticity and their response to external stimuli.