中文摘要：

文章应用密度泛函理论研究接枝于壁面的方阱链对二元小分子混合物的选择性吸附特性.系统的Helmholtz剩余自由能泛函被表示为硬球排斥和方阱吸引两部分贡献之和,分别由硬球链流体状态方程和变阱宽方阱链流体状态方程的简单加权密度近似来进行计算.用此理论方法,分别考察了接枝聚合物的结构性质,以及不同温度下接枝分子层对二元方阱流体的选择性吸附性能.结果表明：分子刷厚度随接枝密度线性增长而随温度非线性增加,并且在高温下趋于饱和;在较低温度下,接枝聚合物刷能表现出很好的选择性吸附能力,当聚合物刷被加热到高于饱和温度时,该能力将大幅度地减弱.

英文摘要：

A density functional approach to the description of the selective adsorption of a binary mixture of small molecules on a surface grafted with the square-well chains is proposed.The excess Helmholtz free energy functional of the system is divided into two contributions from the hard-sphere repulsion and the square-well attraction respectively.In the bulk phase,the equation of state of Liu and Hu （Liu H L,Hu Y 1996 Feuid Phase Equilibra 122 75） is used to calculate the free energy of the repulsive part and the equation of state of Li and He （Li J L and He H H 2009 Feuid Phase Equilibria 276 57） is used to calculate the free energy of the attractive part.A simple weighted density approximation is adopted on both parts to construct the functional.Using this theoretical approach,the structures of the grafted polymers and the selective adsorptions of binary square-well fluids on the grafted layer at different temperatures are investigated.The theory predicts that the brush thickness increases linearly with the grafting density but non-linearly with temperature and the brush thickness tends to sateration at high temperature.Given the chain length and grafting density,the theoretical calculation also reveals that the polymer brush has strong selective adsorption cap ability at low temperature and the cap ability will weaken greatly when the polymer brush is heated above the temperature of sateration.