论文标题
柜台在离子液晶中的作用
The role of counterions in ionic liquid crystals
论文作者
论文摘要
先前基于有效的单物种模型的calamitic（即杆状）离子液体晶体（ILC）的理论研究导致了一种新型的近晶型A相的迹象，其层间距比中源性的长度大得多（即液体 - 晶体形成）。为了排除这种宽术-A相的可能性仅仅是由单物种近似引起的人工制品，我们研究了一个延伸，该扩展是明确说明ILC中阳离子和阴离子的。我们目前由大型蒙特卡洛模拟获得的发现表明，阳离子 - 阳离子系统的各向同性和晶状体A相之间的相变与上一项研究中使用的有效的单物种模型是定性的。特别是，对于具有中源质的ILC（即液 - 晶形成物种），在其尖端上携带带电位点的ILC，在低温和中间密度范围内，在各向同性和六边形晶体相之间。我们发现，在普通的晶状体A期中，中质原子的柜台的空间分布大致均匀，而在宽晶状体A相中，小柜台在近晶层之间积聚。由于这种现象学，对于在移动离子存在电导率通道上取决的应用可能会很有趣。
Previous theoretical studies of calamitic (i.e., rod-like) ionic liquid crystals (ILCs) based on an effective one-species model led to indications of a novel smectic-A phase with a layer spacing being much larger than the length of the mesogenic (i.e., liquid-crystal forming) ions. In order to rule out the possibility that this wide smectic-A phase is merely an artifact caused by the one-species approximation, we investigate an extension which accounts explicitly for cations and anions in ILCs. Our present findings, obtained by grand canonical Monte Carlo simulations, show that the phase transitions between the isotropic and the smectic-A phases of the cation-anion system are in qualitative agreement with the effective one-species model used in the preceding studies. In particular, for ILCs with mesogenes (i.e., liquid-crystal forming species) carrying charged sites at their tips, the wide smectic-A phase forms, at low temperatures and within an intermediate density range, in between the isotropic and a hexagonal crystal phase. We find that in the ordinary smectic-A phase the spatial distribution of the counterions of the mesogens is approximately uniform, whereas in the wide smectic-A phase the small counterions accumulate in between the smectic layers. Due to this phenomenology the wide smectic-A phase could be interesting for applications which hinge on the presence of conductivity channels for mobile ions.
