Shape instabilities driven by topological defects in nematic polymer networks

Paparini, Silvia, Giusteri, Giulio G. and Mihai, L. Angela ORCID: https://orcid.org/0000-0003-0863-3729 2025. Shape instabilities driven by topological defects in nematic polymer networks. Journal of Elasticity 157 (4) , 69. 10.1007/s10659-025-10160-6

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Abstract

Liquid crystalline networks (LCNs) are stimuli-responsive materials formed from polymeric chains cross-linked with rod-like mesogenic segments, which, in the nematic phase, align along a non-polar director. A key characteristic of these nematic systems is the existence of singularities in the director field, known as topological defects or disclinations, and classified by their topological charge. In this study, we address the open question of modeling theoretically the coupling between mesogens disclination and polymeric network by providing a mathematical framework describing the out-of-plane shape changes of initially flat LCN sheets containing a central topological defect. Adopting a variational approach, we define an energy associated with the deformations consisting of two contributions: an elastic energy term accounting for spatial director variations, and a strain-energy function describing the elastic response of the polymer network. The interplay between nematic elasticity, which seeks to minimize distortions in the director field, variations in the degree of order, with the consequent tendency of monomers in the polymer chains to distribute anisotropically in response to an external stimulus, and mechanical stiffness, which resists deformation, determines the resulting morphology. We analyze the transition to instability of the ground-state flat configuration and characterize the corresponding buckling modes.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Mathematics
Publisher:	Springer
ISSN:	0374-3535
Date of First Compliant Deposit:	29 August 2025
Date of Acceptance:	11 August 2025
Last Modified:	02 Sep 2025 08:56
URI:	https://orca.cardiff.ac.uk/id/eprint/180731

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