Berlin 2024 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 29: Gels, Polymer Networks and Elastomers II

CPP 29.2: Vortrag

Mittwoch, 20. März 2024, 15:15–15:30, H 0106

Nonlocal elasticity explains equilibrium patterns in gels induced by phase separation — •Yicheng Qiang, Chengjie Luo, and David Zwicker — Max Planck Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany

Recent experiments found regular patterns in elastic gels, which emerged during cooling-induced phase separation. The patterns form without hysteresis, suggesting a continuous phase transition. To understand these observations, we propose an equilibrium field-based model based on phase separation between an elastic component and the solvent, augmented by nonlocal elasticity, which captures the microstructure of the gel. The model reveals a continuous phase transition from a homogenous state to patterns in stiff gels. Analytical approximations demonstrate that the pattern period is proportional to the geometric mean between the elasto-capillary length and a microscopic length scale of the gel, in good agreement with experimental observations. Our theory highlights the importance of nonlocal elasticity in soft matter systems, reveals the mechanism of equilibrium mesoscopic patterns due to elasticity, and will improve the engineering of such materials with controlled mesoscopic structure.

Keywords: Phase separation; Nonlocal elasticity; Polymer network; Continuous phase transition