Li Fang, Leckband Deborah
Department of Mechanical Science and Engineering, University of Illinois at Urbana and Champaign, MC 712 Urbana, Illinois 61801, USA.
J Chem Phys. 2006 Nov 21;125(19):194702. doi: 10.1063/1.2372493.
This study reports a theoretical analysis of the forced separation of two adhesive surfaces linked via a large number of parallel noncovalent bonds. To describe the bond kinetics, we implement a three-state reaction model with kinetic rates obtained from a simple integral expression of the mean first passage time for diffusive barrier crossing in a pulled-distance-dependent potential. We then compute the rupture force for the separation of adhesive surfaces at a constant rate. The results correspond well with a Brownian dynamics simulation of the same system. The separation rate relative to the intrinsic relaxation time of the bonds defines three loading regimes and the general dependence of the adhesion on kinetic or thermodynamic parameters of the bonds. In the equilibrium regime, the rupture force asymptotically approaches the equilibrium rupture force, which increases linearly with the equilibrium bond energy. In the near-equilibrium regime, the rupture force increases with the separation rate and increasingly correlates with the bond rupture barrier. In the far-from-equilibrium regime where rebinding is irrelevant, the rupture force varies linearly with the rupture barrier.
本研究报告了对通过大量平行非共价键连接的两个粘附表面强制分离的理论分析。为了描述键动力学，我们采用了一个三态反应模型，其动力学速率是从一个简单的积分表达式中获得的，该表达式用于计算在与拉伸距离相关的势场中扩散越过势垒的平均首次通过时间。然后，我们以恒定速率计算粘附表面分离的断裂力。结果与同一系统的布朗动力学模拟结果吻合良好。相对于键的固有弛豫时间的分离速率定义了三种加载模式以及粘附力对键的动力学或热力学参数的一般依赖性。在平衡模式下，断裂力渐近地接近平衡断裂力，该平衡断裂力与平衡键能呈线性增加。在近平衡模式下，断裂力随分离速率增加，并且与键断裂势垒的相关性越来越强。在再结合无关紧要的远非平衡模式下，断裂力随断裂势垒呈线性变化。
