聚电解质溶液中纳米粒子扩散系数的模耦合理论计算  

Diffusion Coefficient of Nanoparticles in Semidilute Polyelectrolyte Solutions Based on Mode Coupling Theory

作　　者：董运洪[1] 陈谙谱 赵南蓉[1] 

机构地区：[1]四川大学化学学院,成都610064

出　　处：《高等学校化学学报》2015年第11期2251-2255,共5页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:21173152;21373141);四川省科技计划项目(批准号:2014JY0234)资助~~

摘　　要：采用模耦合理论(MCT)建立了研究纳米粒子在聚电解质溶液中长时扩散系数D的介观统计方法,提出了有效的聚合物溶液动态散射函数Γpp(k,t)的约化形式.定量计算了溶液微观密度涨落对扩散系数的贡献,考察了扩散系数D对溶液浓度c及纳米粒子半径R的依赖关系,并定量分析了MCT与经典StokesEinstein(S-E)关系的偏离.结果表明,MCT方法的研究结果与实验数据吻合.当纳米粒子尺寸小于聚电解质特征尺寸时,其扩散系数对S-E关系明显偏离.本文建立的基于微观描述的MCT方法为进一步研究纳米粒子在聚合物溶液中的含时扩散动力学行为奠定了理论基础.A theoretical formalism based on mode-coupling theory （MCT） was established to study the long- time diffusion coefficient of nanoparticles in polyelectrolyte solutions. By introducing an approximate summa- tion form for Fpp（k,t） , Dmicro can be calculated straightforwardly and it is necessary to investigate explicitly how D depends on the concentration c of the polymer solution and the nanoparticle size R. For illustration, the theoretical approach is taken to analyze the diffusion of polystyrene nanoparticles in semidilute polyacrylamide solutions which has been studied in detail experimentally. As a result, our theoretical results show very good quantitative agreements with the experimental data in many aspects, such as the strong dependence on c , the large deviation from Stokes-Einstein relation particularly for small particles. Such good agreements clearly demonstrate the validity of our MCT framework, which may serve as a good starting point to study many more complex dynamical behavior associated with polymer solutions.

关 键 词：聚电解质溶液 长时扩散系数 Stokes.Einstein关系 模耦合理论 纳米粒子 

分 类 号：O643[理学—物理化学]