WEB Continuous flow synthesis of patchy particles: Thermal treatment of silica core-particles and the effects of changing surface properties on silver patch growthTuesday (22.09.2020) 14:30 - 14:45 P: Processing and Synthesis 1 Part of:
Patchy particles are a class of material defined as micro- or nanoparticles with surfaces exhibiting distinct regions with different composition or functionality. We developed a simple and scalable continuous flow process for the synthesis of nanometer scale plasmonic patchy particles.- The process is based on a simple aqueous system utilizing the Tollens’ reaction to deposit thin coatings of silver on silica nanoparticles. Patch characteristics such as size and morphology can be modified by changing the size or shape of the core particle or by adjusting process parameters, resulting in easy tunability of plasmonic and optical properties.
In our setup, we separate nucleation and growth of silver patches by changing ammonia concentration by the use of two subsequent mixers (Fig 1a). Since both processes strongly depend on the interaction between the core particle surface and precursors in the reaction medium, any chemical or thermal treatment of the silica particles can influence the resulting patch morphologies and thus the plasmon resonances of the silver coatings. There are several models, such as the Zhuravlev model, to describe the surface chemistry of silica (particles) with respect to calcination temperature.
Bridging over to this model, we investigated the effects of thermal treatment of freshly synthesized silica particles used in our patchy particle process. In this contribution, we present considerable changes of characteristic properties, such as morphology, coverage and yield as well as changes in the plasmonic nature of silver patches, originating from modification of surface chemistry of the core particles (Fig. 1b and c). The findings underline the importance of understanding core-particle properties fully and support the future development of a process-property-relationship model
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