Department of Mechanical Engineering, Binghamton University, The State University of New York, Binghamton, New York 13902, USA.
Soft Matter. 2017 Aug 2;13(30):5137-5149. doi: 10.1039/c7sm00637c.
Using dissipative particle dynamics (DPD), we model the interfacial adsorption of pH-responsive polyelectrolytes and polyelectrolyte-grafted nanoparticles (PNPs) at a planar water-oil interface. The electrostatic interactions in the presence of the dielectric discontinuity across the interface are modeled by exploiting the Groot method, which uses an iterative method to solve the Poisson equation on a uniform grid with distributed charge. We reveal the effects of the pH and salinity of the aqueous solution and the length of the polyelectrolyte on the adsorption behavior of weak polyelectrolytes. The adsorption kinetics is monitored via the trajectory of the center of mass of the polyelectrolyte in the direction normal to the interface. The residence time at the interface and the pair correlation function between the polyelectrolyte and the oil are measured to quantitatively characterize the adsorption. Similar to the weak polyelectrolytes, the influences of pH, salinity and grafted chain length on the adsorption of an individual PNP are explored. Our results show that by grafting polyelectrolytes, the interfacial behavior of the nanoparticles can be tuned by changing the pH and salinity of the solution, which is dictated by the contact angle, the pair correlation function between the particles and the oil, the desorption energy, and the particle morphology at the interface. We also observe that the electrostatic-driven variations in the interfacial activity and morphology of the PNPs are not sensitive to the length of the grafted polyelectrolytes.
利用耗散粒子动力学（DPD），我们模拟了 pH 响应性聚电解质和聚电解质接枝纳米颗粒（PNP）在平面油水界面上的界面吸附。通过利用 Groot 方法模拟界面处存在的介电不连续性的静电相互作用，该方法使用迭代方法在具有分布式电荷的均匀网格上求解泊松方程。我们揭示了水溶液的 pH 值和盐度以及聚电解质长度对弱聚电解质吸附行为的影响。通过沿垂直于界面的方向测量聚电解质质心的轨迹来监测吸附动力学。测量在界面上的停留时间和聚电解质与油之间的对相关函数，以定量表征吸附。与弱聚电解质类似，我们还研究了 pH、盐度和接枝链长对单个 PNP 吸附的影响。我们的结果表明，通过接枝聚电解质，可以通过改变溶液的 pH 值和盐度来调节纳米颗粒的界面行为，这取决于接触角、颗粒与油之间的对相关函数、解吸能和界面上的颗粒形态。我们还观察到，PNP 的界面活性和形态的静电驱动变化对接枝聚电解质的长度不敏感。
