arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1004.2227cond-mat.soft
收藏

螺旋Yukawa杆系统中的胆甾序

Cholesteric order in systems of helical Yukawa rods

H. H. Wensink, G. Jackson

摘要:

本文研究了两个手性棒状胶体之间的相互作用势,这两个胶体由一个薄的圆柱形骨架组成,圆柱表面装饰有螺旋状电荷分布。对于足够细长的螺旋棒一个简单的缩放表达式推导出链接的手性“扭曲”的潜在的固有性质的颗粒,如线圈间距,电荷密度和静电屏蔽参数。为了预测宏观双曲位距的行为,我们引用了一个简单的第二维里理论,该理论适用于弱扭曲指向矢场。虽然弱螺旋杆的螺旋相位的手性总是与内部线圈的手性相称,但更强的螺旋杆显示具有相反手性的螺旋顺序。详细地量化了微观螺旋线的对称性与宏观指向矢场之间的相关性。具有足够不同的长度和线圈节距的混合螺旋引起均匀的非晶相分层成具有不同宏观节距的两个部分。我们的研究结果与实验结果是一致的,可能有助于解释纤维素和几丁质微纤维,DNA和{ \em fd}病毒棒系统中的实验观察。

英文摘要:

We consider the interaction potential between two chiral rod-like colloids which consist of a thin cylindrical backbone decorated with a helical charge distribution on the cylinder surface. For sufficiently slender coiled rods a simple scaling expression is derived which links the chiral `twisting' potential to the intrinsic properties of the particles such as the coil pitch, charge density and electrostatic screening parameter. To predict the behavior of the macroscopic cholesteric pitch we invoke a simple second-virial theory generalized for weakly twisted director fields. While the handedness of the cholesteric phase for weakly coiled rods is always commensurate with that of the internal coil, more strongly coiled rods display cholesteric order with opposite handedness. The correlation between the symmetry of the microscopic helix and the macroscopic cholesteric director field is quantified in detail. Mixing helices with sufficiently disparate lengths and coil pitches gives rise to a demixing of the uniform cholesteric phase into two fractions with a different macroscopic pitch. Our findings are consistent with experimental results and could be helpful in interpreting experimental observations in systems of cellulose and chitin microfibers, DNA and {\em fd} virus rods.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑