多分散高分子固液界面吸附构型的Monte Carlo模拟

在格子模型基础上用M onte Carlo方法模拟研究了多分散高分子在固液界面的吸附行为,重点考察了平均分布和正态分布两种不同链长分布形式的高分子在固液界面吸附构型的分布规律。发现高分子不同的链长分布形式,对高分子吸附构型的性质影响较大。正态分布的高分子体系中高分子的3种吸附构型(T ails,Loops和T rains)的浓度和数目比相同条件下平均分布的高分子体系内要低得多。特别是当高分子链节吸附能较低时,两者的差别非常大。平均分布的高分子体系高分子吸附构型对温度和高分子总链节浓度的变化更加敏感。T ails构型由于受到高分子链节热运动以及吸附层压缩作用的影响,在高温或高吸附作用能下,其密度分布表现出和其他两种吸附构型完全不同的形式。温度、高分子链节吸附作用能以及高分子总链节浓度对3种吸附构型的影响和单分散体系趋势一致,但是存在着定量的差别。

Monte Carlo Simulations for Polymer Conformation of Polydisperse Polymers at Solid-Liquid Interfaces

The adsorption of polydisperse polymers at solid-liquid interfaces is studied by Monte Carlo simulations based on a lattice model.Apparent different conformations are found in the two polydisperse systems.The concentrations of tails,trains and loops in different layers are much lower in normal distribution systems than those in average ones,whereas the change of polymer conformation is more sensitive to temperature and the concentration of the total polymer segments in average distribution systems than that in normal ones.Simulation results also indicate that the concentration of tails in layers which are far away from the adsorption interface increases,while the concentrations of trains and loops decrease rapidly with the increase of temperature.This reveals that more stand-up conformations exist near the adsorption interfaces.This work also suggests that quantitative system errors are likely to be committed if monodisperse models are used to evaluate the real polydisperse polymer systems.