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Geometric thermodynamics of collapse of gels

Raza, A and Das, S and Roy, D (2024) Geometric thermodynamics of collapse of gels. In: Physical Review E, 110 (4).

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Official URL: https://doi.org/10.1103/PhysRevE.110.044102

Abstract

Stimulus-induced volumetric phase transition in gels may be potentially exploited for various bioengineering and mechanical engineering applications. Since the discovery of the phenomenon in the 1970s, extensive experimental research has helped understand the phase transition and related critical phenomena. However, little insight is available on the evolving microstructure. In this article, we aim at unravelling certain geometric aspects of the micromechanics underlying discontinuous phase transition in polyacrylamide gels. Towards this, we use geometric thermodynamics and a Landau-Ginzburg type free energy functional involving a squared gradient, in conjunction with Flory-Huggins theory. We specifically exploit Ruppeiner's approach of Riemannian geometry-enriched thermodynamic fluctuation theory, which was previously employed to investigate phase transitions in van der Waals fluids and black holes. The framework equips us with a scalar curvature that is typically indicative of certain aspects of the microstructure during phase transition. Since previous studies have indicated that curvature divergence relates to correlation length divergence, we infer that the gel possesses a heterogeneous microstructure during phase transition, i.e., at critical points. Curvature also provides an insight into the universality class of phase transition and the nature of polymer-polymer interactions. © 2024 American Physical Society.

Item Type: Journal Article
Publication: Physical Review E
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to the authors.
Keywords: Geometry; Microstructure; Van der Waals forces, Critical phenomenon; During phase; Energy functionals; Engineering applications; Experimental research; Flory-Huggins theory; Mechanical; Polyacrylamide gels; Riemannian geometry; Volumetrics, Free energy
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 30 Oct 2024 03:46
Last Modified: 30 Oct 2024 03:46
URI: http://eprints.iisc.ac.in/id/eprint/86599

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