Electrostatic Repulsion-Controlled Formation of Polydopamine–Gold Janus Particles

• DOI: 10.1021/la302394e
• Publication Date: 2012-08-20T21:18:05Z
• Authors: Haolan Xu; Xiaokong Liu; Ge Su; Bin Zhang; Dayang Wang
• Keywords: Indoles; Molecular Structure; Polymers; Surface Properties; Static Electricity; 01 natural sciences; Gold Compounds; 0104 chemical sciences; Chlorides; Gold; Particle Size; Physical Chemistry (incl. Structural)

Polydopamine (PDA)-Au Janus particles were obtained by simply adding HAuCl(4) to a PDA particle suspension, prepared via self-polymerization of dopamine in basic solution at room temperature. The structures of the PDA-Au particles are readily controlled by electrostatic repulsion between the constituent particles, which can be realized simply via adjusting the environmental pH. PDA-Au Janus particles are formed only in a narrow pH range of 2.5-3.0 due to the properly enhanced electrostatic repulsion between the Au particles growing on as-prepared PDA particles and between the Au and PDA particles. The obtained PDA-Au Janus particles can become interfacially active and self-assemble at oil/water interfaces as a result of spatially well-separated hydrophilic (PDA) and hydrophobic (Au) domains on the surfaces, reminiscent of amphiphilic molecules.