使用布朗動力學模擬探討單鏈高分子的結構與動態特性

Abstract

我們使用布朗動力學模擬研究單一聚合物鏈的結構特徵和動態弛豫。我們強調單一聚合物系統以簡化系統的複雜度，進而研究嫁接對於聚合物在流體內行為之影響。粗粒聚合物由固定數量的單體粒子與虎克彈簧連接而成。單體珠之間的非鍵結相互作用被認為是 Lennard-Jones 電位或指數衰減電位，以解釋單體之間的軟排除體積。粒子之間的成對流體動力相互作用透過體塊的 Rotne-Prager-Yamakawa 張量納入擴散張量中。分析的結構特徵包括聚合物迴轉半徑和端對端距離的分佈函數。鏈的時間鬆弛由粒子的Kirkwood擴散係數和端到端距離的自相關函數來表徵。我們透過先前的研究驗證了遊離聚合物的結果。

We study the structural characteristics and dynamical relaxation of a single polymer chain using Brownian dynamics simulations. We focus on the single polymer to simplify the complexity of the system and further enhance the fundamental understanding of the effect of grafting on the behavior of the polymer in a fluid. The coarse-grained polymer is composed of a fixed number of monomer beads connected with the Hookean springs. The non-bonded interactions between monomer beads are considered as either the Lennard-Jones potential or an exponentially decaying potential accounting for a soft exclude volume between monomers. The pair-hydrodynamic interaction between beads is incorporated in the diffusivity tensor through the Rotne-Prager-Yamakawa tensor for the bulk. The structural characteristics analyzed include the distribution functions of the polymer radius of gyration and the end-to-end distance. The temporal relaxation of the chain is characterized by the Kirkwood diffusion coefficient of the bead and the autocorrelation function for the end-to-end distance. We validate the free polymer results with previous studies.