Prof. Christine Papadakis, TU München

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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