Chiappini Massimiliano, Dijkstra Marjolein
Soft Condensed Matter, Debye Institute for Nanomaterials Science, Department of Physics, Utrecht University, Utrecht, The Netherlands.
Nat Commun. 2021 Apr 12;12(1):2157. doi: 10.1038/s41467-021-22413-8.
In 1976, Meyer predicted that bend distortions of the nematic director field are complemented by deformations of either twist or splay, yielding twist-bend and splay-bend nematic phases, respectively. Four decades later, the existence of the splay-bend nematic phase remains dubious, and the origin of these spontaneous distortions uncertain. Here, we conjecture that bend deformations of the nematic director can be complemented by simultaneous distortions of both twist and splay, yielding a twist-splay-bend nematic phase. Using theory and simulations, we show that the coupling between polar order and bend deformations drives the formation of modulated phases in systems of curved rods. We find that twist-bend phases transition to splay-bend phases via intermediate twist-splay-bend phases, and that splay distortions are always accompanied by periodic density modulations due to the coupling of the particle curvature with the non-uniform curvature of the splayed director field, implying that the twist-splay-bend and splay-bend phases of banana-shaped particles are actually smectic phases.
1976年，迈耶预测向列型指向矢场的弯曲畸变会分别由扭曲或展曲变形来补充，从而分别产生扭曲弯曲和展曲弯曲向列相。四十年后，展曲弯曲向列相的存在仍然存疑，且这些自发畸变的起源也不确定。在此，我们推测向列型指向矢的弯曲变形可以由扭曲和展曲的同时畸变来补充，从而产生扭曲-展曲-弯曲向列相。通过理论和模拟，我们表明极性序与弯曲变形之间的耦合驱动了弯曲棒状体系中调制相的形成。我们发现扭曲弯曲相通过中间的扭曲-展曲-弯曲相转变为展曲弯曲相，并且由于粒子曲率与展曲指向矢场的非均匀曲率的耦合，展曲畸变总是伴随着周期性密度调制，这意味着香蕉形粒子的扭曲-展曲-弯曲相和展曲弯曲相实际上是近晶相。
