Kłos J S
Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland.
Phys Chem Chem Phys. 2018 Jan 24;20(4):2693-2703. doi: 10.1039/c7cp07138h.
The properties of a dendritic polyelectrolyte in equilibrium with a reservoir of monovalent salts are investigated using the cell model and the Poisson-Boltzmann-Flory theory. Within this approach we use the Debye-Hückel approximation to solve the Poisson-Boltzmann equation and minimize the semi-grand potential of the system with respect to the size of the molecule which enables us to inspect its conformations as well as the electric field, the ionic density profile, the overall charge density, the effective charge of the dendrimer and the osmotic pressure based on their response to the salt concentration and the dendrimer charge. The model predicts pronounced trapping of salt ions, a local charge neutrality and a zero electric field in the volume of the molecule as well as oscillations of the density profiles and the electric field in the vicinity of the dendrimer-bulk interface. As a result of ion trapping and screening of Coulomb interactions monovalent salts are found to have a minor effect on the size of the dendrimer. Specifically, the dendrimer exists in slightly swollen states as compared to the neutral molecule which indicates that the conformational properties of the polyelectrolyte depend weakly on monovalent salts. These observations harmonise with the equilibrium behavior of the dendrimer pressure, the internal pressure and the bulk pressure, respectively.
使用细胞模型和泊松-玻尔兹曼-弗洛里理论研究了与单价盐储库处于平衡状态的树枝状聚电解质的性质。在这种方法中，我们使用德拜-休克尔近似来求解泊松-玻尔兹曼方程，并相对于分子大小最小化系统的半巨势，这使我们能够根据它们对盐浓度和树枝状聚合物电荷的响应来检查其构象以及电场、离子密度分布、总电荷密度、树枝状聚合物的有效电荷和渗透压。该模型预测了盐离子的明显捕获、分子体积内的局部电荷中和和零电场，以及树枝状聚合物-本体界面附近密度分布和电场的振荡。由于离子捕获和库仑相互作用的屏蔽，发现单价盐对树枝状聚合物的大小影响较小。具体而言，与中性分子相比，树枝状聚合物以略微膨胀的状态存在，这表明聚电解质的构象性质对单价盐的依赖性较弱。这些观察结果分别与树枝状聚合物压力、内部压力和本体压力的平衡行为相协调。
