Niedner, Lucas

► Research

Synthesis of cationic-anionic and amphiphilic Janus metal oxide nanoparticles for layer-by-layer self-assembly and emulsion stabilization

First introduced by Casagrande in 1989, the term Janus particle (in reference to the roman god of duality) denotes particles that exhibit different optical, magnetic or chemical properties on opposing hemispheres. This enables potential applications in areas such as display technology, biomedicine, catalysis or the textile industry. Due to their high interfacial activity and their tendency to self-assemble, Janus particles are particularly suitable for the deposition on various substrates and for stabilising emulsions.

Within the scope of the research work, (transition) metal oxide nanoparticles are functionalised with various organic coupling reagents. Phosphonic acids that carry either a cationic, anionic or hydrophobic functional group are used for stable covalent bonding on the metal oxide surface. The anisotropic functionalisation takes place in so-called Pickering emulsions in which the particles assemble at the interface of the two immiscible phases. The cationic-anionic Janus particles can now be deposit onto substrates via a layer-by-layer process and the resulting layers can be examined spectroscopically. The amphiphilic particles are used to stabilise emulsions. In systematic studies, the anisotropic Janus particles are then compared with isotropically functionalised analogues.