Abstract

Micro segment flow and micro continuous-flow emulsification have been used for the synthesis of noble metal nanoparticles and polymer/metal composite particles. Beside simple spherical, core/shell and core/double shell-particles, nanotriangles, rods, cubes of silver and gold have been obtained by flow-synthesis in high yield and homogeneity as well as ellipsoidal, dumbbell-shaped, rod-like and branched polymer nanoparticles. A micro flow photochemical nanoparticle synthesis was developed for gold nanoparticles and could be transferred on to the synthesis of nanoparticles of the platinum group which are particular interesting for heterogeneous catalysis.

The high homogeneity of formed products allowed investigations on the effect of electrical charges on the formation of non-spherical particles resulting in a general concept of electrostatically controlled nanoparticle formation. Different techniques of surface modification have been applied for control of surface charges and to manage particle/particle interactions and formation of composed microparticles. It was possible to prepare hierarchically composed microparticles with up to four levels of spatial organization between the nanometer and the sub-millimeter scale. Among the composed particles, swellable polymer micro particles containing platinum and silver nanoparticles have been applied in catalytic continuous flow experiments and for particle-based sensing by a strong surface-enhanced Raman effect (SERS).