论文标题
nematic lyotropic Chromonic液体晶体dododium lasogoglycate的剪切诱导的多域结构
Shear-induced polydomain structures of nematic lyotropic chromonic liquid crystal disodium cromoglycate
论文作者
论文摘要
综合性染色体液体晶体（LCLC）代表形成圆柱骨料的有机盘状分子的水分散体。尽管对这些材料感兴趣，但它们的流动行为知之甚少。在这里，我们探讨了剪切对列表LCLC动态结构的影响，由14wt $ {\％} $形成，d disodium cromoglycate（DSCG）的水分散体。我们采用原位偏振光学显微镜（POM）以及小角度和广角X射线散射（SAXS/WAXS），以在较大的剪切速率上获得有关导演结构的独立和互补信息。 DSCG列表显示了具有两个剪切的区域（$ \dotγ<1 \ 1区域I区域i \，s^{ - 1} $和$ \dotγ> 10 s^{ - 1} $的区域III，由Pseudo-Newtonian Region Inearian Ineage ii II（$ 1 s^$ s^$ s^{-1} <10 s} <10 s^10 s^<10 s^<10 s^10 s该材料是一种翻滚类型。在区域I中，$ \dotγ<1 s^{ - 1} $，导演沿涡旋轴重新调整。 $ \dotγ$以上的$ 1 s^{ - 1} $触发了披露循环的成核。这些脱节引入了导演的斑块，该贴片偏离涡度方向并形成多域纹理。沿流量和涡旋方向的域的扩展随着剪切速率增加到$ 10 s^{ - 1} $而降低。高于$ 10 s^{ - 1} $，域开始沿流延伸。在$ \dotγ> 100 s^{ - 1} $的情况下，纹理演变成周期性的条纹，其中导演主要沿着左右倾斜的流程沿着流程。条纹时期随着$ \dotγ$的增加而减小。剪切诱导的转化是通过弹性和粘性能量的平衡来解释的。特别是，脱节的成核与将非主导域与不同导演倾斜分开的壁上的弹性能量增加有关。
Lyotropic chromonic liquid crystals (LCLCs) represent aqueous dispersions of organic disk-like molecules that form cylindrical aggregates. Despite the growing interest in these materials, their flow behavior is poorly understood. Here, we explore the effect of shear on dynamic structures of the nematic LCLC, formed by 14wt ${\%}$ water dispersion of disodium cromoglycate (DSCG). We employ in-situ polarizing optical microscopy (POM) and small-angle and wide-angle X-ray scattering (SAXS/WAXS) to obtain independent and complementary information on the director structures over a wide range of shear rates. The DSCG nematic shows a shear-thinning behavior with two shear-thinning regions (Region I at $\dotγ<1\,s^{-1}$ and Region III at $\dotγ>10 s^{-1}$) separated by a pseudo-Newtonian Region II ($1 s^{-1}<\dotγ<10 s^{-1}$). The material is of a tumbling type. In Region I, $\dotγ<1 s^{-1}$, the director realigns along the vorticity axis. An increase of $\dotγ$ above $1 s^{-1}$ triggers nucleation of disclination loops. The disclinations introduce patches of the director that deviates from the vorticity direction and form a polydomain texture. Extension of the domains along the flow and along the vorticity direction decreases with the increase of the shear rate to $10 s^{-1}$. Above $10 s^{-1}$, the domains begin to elongate along the flow. At $\dotγ>100 s^{-1}$, the texture evolves into periodic stripes in which the director is predominantly along the flow with left and right tilts. The period of stripes decreases with an increase of $\dotγ$. The shear-induced transformations are explained by the balance of the elastic and viscous energies. In particular, nucleation of disclinations is associated with an increase of the elastic energy at the walls separating nonsingular domains with different director tilts.
