在良溶剂中竞争聚合物在平面表面上的吸附动力学。

Physical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, S-221 00 Lund, Sweden.

J Phys Chem B. 2010 Mar 25;114(11):3741-53. doi: 10.1021/jp908676p.

Adsorption of mixed polymer solutions in good solvent containing polymers of different chain length has been studied by applying simulation techniques on a coarse-grained bead-spring polymer model. Fully flexible polymers at varying bead-surface interaction strength and different combinations of flexible, semiflexible, and stiff polymers at a single bead-surface interaction strength have been examined. Monte Carlo simulation techniques have been employed to investigate static equilibrium properties and Brownian dynamic simulations to follow the dynamics of the adsorption process. The properties examined comprise the adsorbed number of polymers, adsorbed number of beads, bead density profiles, components of the polymer radius of gyration, tail, loop, and train configurations, and nematic bond order of adsorbed beads. The adsorption involves an initially independent adsorption of the two polymer types followed by competitive adsorption. The competitive adsorption is characterized by a maximum of the adsorbed amount and a desorption of the polymer with the smallest surface affinity and a continued, but reduced, growth of the adsorbed amount of the polymer with the largest surface affinity. The surface affinity difference between the two polymer types of different length increased with increasing bead-surface interaction. Furthermore, the surface affinity of a polymer initially decreased but then largely increased at increasing stiffness. As a consequence, a stiff short polymer was found to displace a 4-fold longer flexible polymer. The spatial extension of adsorbed polymers as characterized by the radius of gyration parallel and perpendicular to the surface of a polymer of a given flexibility was independent of the flexibility of the other polymer type. The fraction of beads in tails was increased and in trains reduced as the surface affinity of the dissimilar polymer type was raised. Finally, the adsorption layer of a stiff polymer possesses a nematic bond order. In mixed polymer systems, the nematic bond order of a given polymer type manifests a dependence on the flexibility of the other type.

在包含不同链长聚合物的良溶剂中混合聚合物溶液的吸附已通过在粗粒珠-弹簧聚合物模型上应用模拟技术进行了研究。在不同珠-表面相互作用强度和单个珠-表面相互作用强度下的柔性、半柔性和刚性聚合物的不同组合下，检查了完全柔性聚合物。已经采用了蒙特卡罗模拟技术来研究静态平衡性质和布朗动态模拟来跟踪吸附过程的动力学。所检查的性质包括吸附的聚合物数量、吸附的珠数、珠密度分布、聚合物回转半径的分量、尾、环和链配置以及吸附珠的向列键序。吸附涉及两种聚合物类型的初始独立吸附，然后是竞争性吸附。竞争性吸附的特点是吸附量最大，表面亲和力最小的聚合物解吸，并且表面亲和力最大的聚合物的吸附量继续但减少。两种不同长度的聚合物类型之间的表面亲和力差异随珠-表面相互作用的增加而增加。此外，聚合物的表面亲和力最初降低，但随后随着刚性的增加而大大增加。因此，发现刚性短聚合物取代了 4 倍长的柔性聚合物。用给定的柔性聚合物的表面平行和垂直的回转半径来表征吸附聚合物的空间扩展与其他聚合物类型的柔性无关。随着不同类型聚合物的表面亲和力的增加，尾部分子的比例增加，而在列车中的比例减少。最后，刚性聚合物的吸附层具有向列键序。在混合聚合物系统中，给定聚合物类型的向列键序表现出对另一种类型的柔性的依赖性。