Lin Yong, Liao Qi, Jin Xigao
State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
J Phys Chem B. 2007 May 31;111(21):5819-28. doi: 10.1021/jp070514l. Epub 2007 May 8.
We present the results of molecular dynamics simulations of dendritic polyelectrolytes in dilute salt-free solutions. The dendritic polyelectrolytes are modeled as an ensemble of regular-branched bead-spring chains of neutral and charged Lennard-Jones particles with explicit counterions. A wide range of molecular variables of the dendritic polyelectrolytes such as generation number, spacer length, and charge density were considered in the simulations. The effect of dendrimer size on relaxation time, the conformation of spacers, and the size dependence of the dendrimer on molecular variables are discussed and compared with a Flory type theory. The osmotic coefficients of the dilute dendritic polyelectrolyte solutions, as well as the profiles of monomers and counterions, are calculated directly from the simulations. Our simulation results show that the inner spacers of the dendrimers are extensively stretched, and the size dependence on the molecular weight deviates from the scaling prediction that assumes a Gaussian elasticity of the spacer.
我们展示了无盐稀溶液中树枝状聚电解质的分子动力学模拟结果。树枝状聚电解质被建模为带有明确抗衡离子的中性和带电 Lennard-Jones 粒子的规则分支珠链弹簧链的集合。模拟中考虑了树枝状聚电解质的多种分子变量，如代数、间隔长度和电荷密度。讨论了树枝状聚合物尺寸对弛豫时间、间隔构象的影响，以及树枝状聚合物尺寸对分子变量的依赖性，并与弗洛里类型理论进行了比较。直接从模拟中计算了稀树枝状聚电解质溶液的渗透系数以及单体和抗衡离子的分布。我们的模拟结果表明，树枝状聚合物的内部间隔被广泛拉伸，并且尺寸对分子量的依赖性偏离了假设间隔具有高斯弹性的标度预测。
