Cholesteric liquid crystal gels with a graded mechanical stress

Gonzague Agez (1, 2) , Sabrina Relaix (1, 3) , Michel Mitov (1, 2)

1 CEMES - Centre d'élaboration de matériaux et d'études structurales
2 CEMES-NeO - Nano-Optique et Nanomatériaux pour l'optique
3 CRMAA - Centre de Recherche sur les Matériaux Auto-Assemblés

In cholesteric liquid-crystalline gels, the mechanical role of the polymer network over the structure of the whole gel has been ignored. We show that it is the stress gradient exerted by the network over the helical structure that drives the broadening of the optical band gap, as evidenced by the absence of a gradient in chiral species. Model calculations and finite-difference time-domain simulations show that the network acts as a spring with a stiffness gradient. The present results indicate a revision to the common understanding of the physical properties of liquid-crystalline gels is necessary when a concentration gradient in a polymer network is present.

Domaines: Matière Molle [cond-mat.soft]

Gonzague Agez, Sabrina Relaix, Michel Mitov. Cholesteric liquid crystal gels with a graded mechanical stress. Physical Review E , 2014, 89 (2), pp.022513. ⟨10.1103/PhysRevE.89.022513⟩. ⟨hal-01730532⟩