Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 69: Focus: Polymers in Multi-Component and Aqueous Solutions I - organized by Jens-Uwe Sommer and Debashish Mukherji

CPP 69.5: Vortrag

Donnerstag, 15. März 2018, 16:15–16:30, C 130

Kinetics of Mesoglobule Formation in Dependence on Pressure of Aqueous Poly(N-isopropylacrylamide) Solutions — •Bart-Jan Niebuur¹, Leonardo Chiappisi², Xiaohan Zhang¹, Florian Jung¹, Vitaliy Pipich³, Marie-Sousai Appavou³, Alfons Schulte⁴, and Christine M. Papadakis¹ — ¹TU München, Physik-Department, Garching, Germany — ²Institut Laue-Langevin, Grenoble, France — ³JCNS at MLZ, FZ Jülich, Garching, Germany — ⁴University of Central Florida, Department of Physics, Orlando, U.S.A.

Aqueous solutions of the thermoresponsive polymer Poly(N-isopropylacrylamide) form stable mesoglobules above their cloud point. Their size and degree of hydration depend strongly on pressure [1]. To elucidate the early stages of mesoglobule growth, time-resolved small-angle neutron scattering is applied during pressure jumps which induce phase separation. In this way, the phase-separated state is reached extremely fast within few ms. At low pressure, two different growth processes are observed. The early stage of aggregation is diffusion-limited, followed by the appearance of an energy barrier, hindering the growth during later stages. The time at which the energy barrier starts to dominate depends strongly on the target pressure of the jump. At high pressure, only one growth process is observed, and the energy barrier hindering the aggregation is much smaller than at low pressure. Thus, the growth behavior seems to be closely related to the hydration state of the polymeric chains [1].

[1] B.-J. Niebuur et al., ACS Macro Lett. 6, 1180 (2017)