Abstract

Separation is an important process in science and technology. Nano-structures are being used widely to improve the resolution and speed of the separation process. For this purpose, the motion of a charged polymer in an asymmetric nano-channel under constant and alternating applied electric fields are studied in this manuscript. Computer simulations and theoretical considerations are used to find the optimal condition for the nano-channel as a separation device. It is shown recently that an asymmetric channel acts as an entropic rectifier for polymers in an alternating electric field. Here, the mechanism of polymer motion in the channel, composed of consecutive nano-cones, is investigated based on the role of entropic traps. Entropic traps are referred to the narrow constrictions before the cones. It is shown that the characteristic time for the polymers to put their monomers in front of narrow constrictions (trapping time) becomes determining, in smaller electric fields. Dependence of the polymer velocity in the channel on the strength of the electric field, the cone angle and the time period of the electric field is discussed. Finally, the difference between velocities of polymers of various lengths is considered, which is an important parameter for the separation purposes.

Graphic abstract

中文翻译：

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聚合物在不对称纳米通道中运动的校正机理

摘要

分离是科学技术中的重要过程。纳米结构被广泛用于提高分离过程的分辨率和速度。为此，本文研究了带电聚合物在恒定和交替施加的电场下在不对称纳米通道中的运动。计算机模拟和理论考虑被用来找到纳米通道作为分离装置的最佳条件。最近表明，不对称通道在交变电场中充当聚合物的熵整流器。在此，基于熵陷阱的作用，研究了由连续的纳米锥组成的通道中聚合物运动的机理。熵阱指的是锥形之前的狭窄缩颈。结果表明，在较小的电场中，聚合物将其单体置于狭窄缩颈前面的特征时间（捕获时间）变得很重要。讨论了通道中聚合物速度对电场强度，锥角和电场时间的依赖性。最后，考虑了各种长度的聚合物的速度之间的差异，这是分离目的的重要参数。

图形摘要