拉伸应力下Polymer链的热断裂和自愈合
Thermal Breakage and Self-Healing of a Polymer Chain under Tensile Stress
摘要：
本文研究了由Morse势耦合的离散链段组成的束缚高分子链在恒定拉伸应力下的热断裂。在断裂开始时的链动力学分析研究Kramers-Langer多维理论和广泛的分子动力学模拟在1D和3D空间。与一维和三维模拟数据的比较表明，Kramers-Langer理论对{ \em集体}不稳定模式引起的键断过程提供了很好的定性描述。我们推导出断裂概率分布在连续的债券沿链，揭示了链端断裂的影响与理论吻合得很好。单个键的断裂时间分布符合理论预测的指数规律。特别注意的是集中在断裂键的重组（自我修复）。理论推导的复合时间和距离分布的表达式符合MD观测，并表明能垒位置交叉是不是一个很好的标准真正的破裂。结果表明，自愈合键的分数随着温度和摩擦的升高而增加。
英文摘要：
We consider the thermal breakage of a tethered polymer chain of discrete segments coupled by Morse potentials under constant tensile stress. The chain dynamics at the onset of fracture is studied analytically by Kramers-Langer multidimensional theory and by extensive Molecular Dynamics simulations in 1D- and 3D-space. Comparison with simulation data in one- and three dimensions demonstrates that the Kramers-Langer theory provides good qualitative description of the process of bond-scission as caused by a {\em collective} unstable mode. We derive distributions of the probability for scission over the successive bonds along the chain which reveal the influence of chain ends on rupture in good agreement with theory. The breakage time distribution of an individual bond is found to follow an exponential law as predicted by theory. Special attention is focused on the recombination (self-healing) of broken bonds. Theoretically derived expressions for the recombination time and distance distributions comply with MD observations and indicate that the energy barrier position crossing is not a good criterion for true rupture. It is shown that the fraction of self-healing bonds increases with rising temperature and friction.
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