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CeNS Colloquium

Date:15.01.2020, Time: 15:30h

Kinetics of phase separation and dissolution in solutions of thermoresponsive polymers after fast pressure jumps

Prof. Christine Papadakis, TU M√ľnchen

The thermoresponsive polymer PNIPAM in aqueous solution features lower critical solution behavior. Its cloud point depends on pressure with the coexistence line being an ellipse in the temperature-pressure frame [1]. Performing fast pressure jumps across the coexistence line along with time-resolved small-angle neutron scattering, we can follow the pathway of aggregate formation and of aggregate disintegration with a time resolution of 50 ms and over a wide range of length scales [2]. The pathways at low and at high pressures are vastly different, because the hydration state of PNIPAM depends strongly on pressure [3]. Varying the target pressure gives insight into the role of kinetic and thermodynamic factors.

1. B.-J. Niebuur, C.M. Papadakis et al., ACS Macro Lett. 6, 1180 (2017)
2. B.-J. Niebuur, C.M. Papadakis et al., ACS Macro Lett. 7, 1155 (2018).
3. B.-J. Niebuur, C.M. Papadakis et al., Macromolecules 52, 6416 (2019).

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