Division of Chemistry andChemical Engineering, California Institute of TechnologyPasadena, Pasadena, California 91125,USA.
J Chem Phys. 2017 Feb 28;146(8):084901. doi: 10.1063/1.4975777.
We address the effects of chain connectivity on electrostaticfluctuations in polyelectrolyte solutions using a field-theoretic, renormalizedGaussian fluctuation (RGF) theory. As in simple electrolyte solutions [Z.-G. Wang,Phys. Rev. E 81, 021501 (2010)], the RGF provides a unified theory forelectrostatic fluctuations, accounting for both dielectric and charge correlationeffects in terms of the self-energy. Unlike simple ions, the polyelectrolyte self energydepends intimately on the chain conformation, and our theory naturally provides aself-consistent determination of the response of intramolecular chain structure topolyelectrolyte and salt concentrations. The effects of the chain-conformation on theself-energy and thermodynamics are especially pronounced for flexiblepolyelectrolytes at low polymer and salt concentrations, where application of thewrong chain structure can lead to a drastic misestimation of the electrostaticcorrelations. By capturing the expected scaling behavior of chain size from dilute tosemi-dilute regimes, our theory provides improved estimates of the self energy at lowpolymer concentrations and correctly predicts the eventual N-independenceof the critical temperature and concentration of salt-free solutions of flexiblepolyelectrolytes. We show that the self energy can be interpreted in terms of aninfinite-dilution energy μ and a finite concentrationcorrelation correction μ which tends to cancel out the formerwith increasing concentration.
我们使用场论、重整化高斯涨落（RGF）理论来研究链连接性对聚电解质溶液中静电涨落的影响。与简单电解质溶液[Z.-G. Wang, Phys. Rev. E 81, 021501 (2010)]一样，RGF 提供了一种统一的静电涨落理论，用自能来描述介电和电荷相关效应。与简单离子不同，聚电解质的自能与链构象密切相关，我们的理论自然提供了聚电解质和盐浓度对内部分子链结构响应的自洽确定。对于低聚合物和盐浓度下的柔性聚电解质，链构象对自能和热力学的影响尤其显著，在这种情况下，如果使用错误的链结构，可能会导致对静电相关性的严重估计错误。通过捕捉从稀溶液到半稀溶液的链尺寸的预期标度行为，我们的理论在低聚合物浓度下提供了自能的改进估计，并正确预测了无盐柔性聚电解质溶液的临界温度和浓度最终趋于 N 无关。我们表明，自能可以用无限稀释能量μ和有限浓度相关修正μ来解释，随着浓度的增加，后者趋于抵消前者。
