F.-A. Forel Institute Group of Environmental Physical Chemistry, University of Geneva, 10 Route de Suisse, 1290 Versoix, Switzerland.
J Phys Chem B. 2011 Oct 27;115(42):12007-18. doi: 10.1021/jp205616e. Epub 2011 Sep 30.
Complex formation between a weak flexible polyelectrolyte chain and one positively charged nanoparticle in presence of explicit counterions and salt particles is investigated using Monte Carlo simulations. The influence of parameters such as the nanoparticle surface charge density, salt valency, and solution property such as the pH on the chain protonation/deprotonation process and monomer adsorption at the nanoparticle surface are systematically investigated. It is shown that the nanoparticle presence significantly modifies chain acid/base and polyelectrolyte conformational properties. The importance of the attractive electrostatic interactions between the chain and the nanoparticle clearly promotes the chain deprotonation leading, at high pH and nanoparticle charge density, to fully wrapped polyelectrolyte at the nanoparticle surface. When the nanoparticle bare charge is overcompensated by the polyelectrolyte charges, counterions and salt particles condense at the surface of the polyelectrolyte-nanoparticle complex to compensate for the excess of charges providing from the adsorbed polyelectrolyte chain. It is also shown that the complex formation is significantly affected by the salt valency. Indeed, with the presence of trivalent salt cations, competition is observed between the nanoparticle and the trivalent cations. As a result, the amount of adsorbed monomers is less important than in the monovalent and divalent case and chain conformations are different due to the collapse of polyelectrolyte segments around trivalent cations out of the nanoparticle adsorption layer.
在存在显式抗衡离子和盐颗粒的情况下，使用蒙特卡罗模拟研究了弱柔性聚电解质链与带正电荷的纳米颗粒之间的络合形成。系统研究了纳米颗粒表面电荷密度、盐价和溶液性质（如 pH 值）等参数对链质子化/去质子化过程和单体在纳米颗粒表面吸附的影响。结果表明，纳米颗粒的存在显著改变了链的酸碱和聚电解质构象性质。链和纳米颗粒之间的吸引力静电相互作用的重要性明显促进了链的去质子化，导致在高 pH 值和纳米颗粒电荷密度下，完全包裹在纳米颗粒表面的聚电解质。当纳米颗粒的裸电荷被聚电解质电荷过度补偿时，抗衡离子和盐颗粒在聚电解质-纳米颗粒复合物的表面凝聚，以补偿吸附聚电解质链提供的过量电荷。还表明，盐价对复合物的形成有显著影响。实际上，在存在三价盐阳离子的情况下，观察到纳米颗粒和三价阳离子之间的竞争。结果，吸附单体的量比一价和二价情况要少，并且由于聚电解质段在纳米颗粒吸附层之外围绕三价阳离子坍塌，链构象也不同。
