疏水缔合聚合物溶液性质的耗散颗粒动力学模拟

Dissipative Particle Dynamics Simulation of Hydrophobically Associating Polymer Solution

本文利用耗散颗粒动力学模拟方法,研究了疏水缔合聚合物溶液黏度随浓度、温度、剪切程度等条件的变化,并模拟了聚合物在油水体系中的聚集行为。研究发现,疏水缔合聚合物在溶液中表现出类似表面活性剂的聚集行为,其黏度随外界影响因素变化主要是由于溶液中聚合物聚集结构的转变。聚合物浓度较低时,聚合物主要以分子内缔合作用为主;随着浓度的增加,产生分子间缔合,并逐步形成相互交联的空间网络,水珠子的扩散率逐渐变小,体系黏度增加。当温度较低时,体系呈现较多柱状聚集结构,黏度较高;随着模拟温度升高,尺寸较大的棒状聚集体转变为球状聚集体,水珠子扩散率不断增加,体系黏度逐渐降低。随着体系剪切速率的提高,聚合物分子在受力方向上取向趋于一致,分子间缠绕和缔合程度减轻,水珠子扩散率急剧增加,体系黏度降低。另外,疏水缔合聚合物易吸附于油水界面,对油水体系的乳化和相转变产生一定影响。

Using dissipative particle dynamics simulation, the viscosity of hydrophobically associating polymer （HAP） solution was studied with different concentrations, temperatures and shear strengths respectively, and the assembly behavior was also simulated in water-oil system. It was found that the assembly behavior of HAP was similar to surfactant. The change of viscosity was attributed to different assembly structure. Lower viscosity was due to intramolecular associating of HAP, and higher value derived from lower diffusivity of water beads was for the spatial network forming by intermolecular associating with the increase of polymer concentration. Also, the structures of system changed from columned assemblies to spherical ones when the temperature increased, which exhibited lower viscosity and higher diffusivity of water particles. With increasing shearing rate, the macromolecules were realigned along the shear stress and the associated degree of polymer fell sharply, and the viscosity thus decreased. Meanwhile, HAP could easily absorb at water-oil interface, and influence their emulsification and phase transition.