Regensburg 2019 – wissenschaftliches Programm
DY 2.3: Vortrag
Montag, 1. April 2019, 10:00–10:15, H8
Formation and growth of mesoglobules in aqueous poly(N-isopropylacrylamide) solutions at low and high pressures revealed with fast pressure jumps — •Bart-Jan Niebuur1, Leonardo Chiappisi2, Florian Jung1, Xiaohan Zhang1, Alfons Schulte3, and Christine M. Papadakis1 — 1TU München, Physik Department, Physik weicher Materie, Garching, Germany — 2Institut Laue-Langevin, Large Scale Structures Group, Grenoble, France — 3University of Central Florida, Department of Physics and College of Optics and Photonics, Orlando, U.S.A.
Understanding the kinetics of phase separation is of importance for numerous systems. The thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAM) presents a model system to investigate the kinetics of phase separation. In aqueous solutions at temperatures above the cloud point, PNIPAM forms stable mesoglobules with their size and hydration state depending strongly on pressure . To elucidate the formation and early stage growth of the mesoglobules, we applied time-resolved small-angle neutron scattering after rapid pressure jumps inducing phase separation at low and high pressures. We find that mesoglobule formation includes the formation of small clusters, growth by diffusion-limited coalescence, and the formation of a dense shell, slowing down further coalescence . The strong dehydration at low pressures results in much slower kinetics than at high pressures, where the chains stay more hydrated.  B.-J. Niebuur, C. M. Papadakis et al., ACS Macro Lett. 2017, 6, 1180.  B.-J. Niebuur, C. M. Papadakis et al., ACS Macro Lett. 2018, 7, 1155