Regensburg 2019 – wissenschaftliches Programm
CPP 25.10: Poster
Dienstag, 2. April 2019, 14:00–16:00, Poster B1
Pressure-induced phase transition in silica nanoparticle-polymer solutions — •Marc Moron, Julian Schulze, Julia Nase, Michael Paulus, and Metin Tolan — Fakultät Physik/DELTA, TU Dortmund, 44221 Dortmund, Germany
Nanoparticles are in the focus of current research because they are important for many applications like thermal energy storage or med- ical chemistry. Silica nanoparticles in aqueous solution show a repul- sive Coulomb interaction. By adding non-adsorbing polymers (e.g. polyethylene glycol), the total particle-particle interaction can become more attractive. With increasing polymer concentration, the system undergoes a phase transition from the homogenous phase into a liquid- liquid phase separated phase (LLPS). If the system is exposed to high pressure the system switches back into the homogenous phase. In this work, light transmission and small-angle X-ray scattering measure- ments on systems, containing 1 wt.% silica nanoparticles and various molecular weight and concentration of PEG, were performed to un- derstand of the phase transition on a microscopic level. By combin- ing these techniques, we were able to determine a pressure-dependent phase diagram, and obtained information about typical distances be- tween the nanoparticles in the LLPS phase. The measurements showed that the transition pressure strongly depends on concentration and the size ratio between the polymers and the nanoparticles.