Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States.
J Phys Chem B. 2011 Jun 9;115(22):7206-17. doi: 10.1021/jp108806v. Epub 2011 Mar 8.
We introduce a continuum description of the thermodynamics of colloids with a core-corona architecture. In the case of thick coronas, their overlap can be treated approximately by replacing the exact one-particle density distribution by a suitably shaped step profile, which provides a convenient way of modeling the spherical, columnar, lamellar, and inverted cluster morphologies predicted by numerical simulations and the more involved theories. We use the model to study monodisperse particles with the hard-core/square-shoulder pair interaction as the simplest representatives of the core-corona class. We derive approximate analytical expressions for the enthalpies of the cluster morphologies which offer a clear insight into the mechanisms at work, and we calculate the lattice spacing and the cluster size for all morphologies of the phase sequence as well as the phase-transition pressures. By comparing the results with the exact crystalline minimum-enthalpy configurations, we show that the accuracy of the theory increases with shoulder width. We discuss possible extensions of the theory that could account for the finite-temperature effects.
我们介绍了一种具有核壳结构的胶体热力学的连续体描述。对于较厚的壳层，它们的重叠可以通过用合适形状的阶跃分布来近似取代精确的单粒子密度分布来处理，这为模拟数值模拟和更复杂理论预测的球形、柱状、层状和倒团聚形态提供了一种方便的方法。我们使用该模型来研究具有硬芯/方肩对相互作用的单分散颗粒，作为核壳类的最简单代表。我们推导出了簇形态的焓的近似解析表达式，这为工作机制提供了清晰的认识，并且我们计算了所有形态的晶格间距和簇大小以及相变压力。通过将结果与精确的晶状最小焓构型进行比较，我们表明理论的准确性随肩宽的增加而提高。我们讨论了可能扩展该理论以考虑有限温度效应的方法。
