Physical Chemistry Laboratory, Chemical Engineering Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
J Chem Phys. 2012 Oct 14;137(14):144905. doi: 10.1063/1.4757666.
Models of mixtures of peripherally charged dendrimers with oppositely charged linear polyelectrolytes in the presence of explicit solvent are studied by means of molecular dynamics simulations. Under the influence of varying strength of electrostatic interactions, these systems appear to form dynamically arrested film-like interconnected structures in the polymer-rich phase. Acting like a pseudo-thermodynamic inverse temperature, the increase of the strength of the Coulombic interactions drive the polymeric constituents of the mixture to a gradual dynamic freezing-in. The timescale of the average density fluctuations of the formed complexes initially increases in the weak electrostatic regime reaching a finite limit as the strength of electrostatic interactions grow. Although the models are overall electrically neutral, during this process the dendrimer/linear complexes develop a polar character with an excess charge mainly close to the periphery of the dendrimers. The morphological characteristics of the resulted pattern are found to depend on the size of the polymer chains on account of the distinct conformational features assumed by the complexed linear polyelectrolytes of different length. In addition, the length of the polymer chain appears to affect the dynamics of the counterions, thus affecting the ionic transport properties of the system. It appears, therefore, that the strength of electrostatic interactions together with the length of the linear polyelectrolytes are parameters to which these systems are particularly responsive, offering thus the possibility for a better control of the resulted structure and the electric properties of these soft-colloidal systems.
在外加溶剂存在的情况下，通过分子动力学模拟研究了带负电荷的树枝状大分子与带相反电荷的线性聚电解质混合物的模型。在静电相互作用强度变化的影响下，这些系统在聚合物富相中似乎形成了动态固定的膜状互联结构。类似于伪热力学逆温度，库仑相互作用强度的增加导致混合物的聚合成分逐渐冻结。形成复合物的平均密度涨落的时间尺度在弱静电区初始增加，当静电相互作用强度增加时达到有限极限。尽管这些模型总体上是电中性的，但在这个过程中，树枝状大分子/线性复合物表现出极性特征，主要在树枝状大分子的外围带有多余电荷。所得到的图案的形态特征被发现取决于聚合物链的大小，这是由于不同长度的复合线性聚电解质具有不同的构象特征。此外，聚合物链的长度似乎影响反离子的动力学，从而影响系统的离子输运性质。因此，似乎静电相互作用的强度以及线性聚电解质的长度是这些系统特别敏感的参数，从而为更好地控制所得结构和这些软胶体系统的电性质提供了可能性。
