Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: Hydrogels and Microgels

CPP 8.1: Hauptvortrag

Montag, 7. März 2016, 15:00–15:30, H40

The role of nonlinearities and kinetics at phase transitions in stimuli-responsive polymer solutions and hydrogels — •Martine Philipp, Winfried Petry, and Peter Müller-Buschbaum — TU München, Physik-Department, LS Funktionelle Materialien, 85748 Garching, Germany

Soft condensed matter often self-assembles in a very rich and complex morphology. Typical examples include block copolymer, surfactant, and colloidal systems. Understanding self-assembly involves understanding of phase transitions, particularly of demixing phase transitions, including their kinetics. Crucial parameters on molecular scales are changes in intermolecular interactions, in conformations, and transport processes. During phase transformations, states of less stability are generally passed through. This potentially provokes mechanical instabilities, manifesting by softening. As the linear elastic moduli are small for intrinsically soft materials and as they might even further decrease by transition-induced softening, one can speculate whether elastic nonlinearities can dominate the elastic instability, and hence self-assembly. Analogies known from solid state physics are acoustic soft modes, which govern structural phase transitions in ferroelastic crystals.

In this talk, the impact of elastic, thermo-mechanical and thermo-optical nonlinearities on the order parameter susceptibilities will be discussed for so-called volume phase transitions within stimuli-responsive polymer solutions and hydrogels. First insights into a molecular-mechanistic understanding are presented.