Colloidal systems show beautiful examples of how entropy can lead to self-assembly of ordered structures, challenging our perception of disorder. In fact, dispersion of hard colloidal particles, systems in which by default entropy is the only thermodynamic driving force, displays both translational and orientational order on increasing density. Entropy is also a fundamental concept for describing effective interactions between colloidal particles. In several cases, entropy maximization generates strong attractive forces, capable of inducing condensation and sometimes crystallization. These entropic forces can even be exploited to drive colloids in specific locations or to orient them in the build-up of supracolloidal aggregates. Depletion interactions and combinatorial contributions are two important manifestations of these forces. Entropy also plays a leading role in systems exploring the bottom of their potential energy surface. In patchy colloids, particles interacting with highly anisotropic and localized potentials, ground-state structures are often degenerate in energy, leaving entropy to decide the thermodynamically stable polymorph. A striking result is the possibility of generating colloidal “liquids” thermodynamically more stable than colloidal “crystals” even at vanishing temperature.

中文翻译：

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自组装中的熵

胶体系统显示了熵如何导致有序结构自组装，挑战我们对无序感知的美丽示例。实际上，在默认情况下熵是唯一的热力学驱动力的系统中，硬胶体颗粒的分散在密度增加时显示出平移和取向顺序。熵还是描述胶体粒子之间有效相互作用的基本概念。在某些情况下，熵最大化会产生强大的吸引力，从而能够引起凝聚甚至结晶。这些熵力甚至可以被用来在特定位置驱动胶体或将胶体定向到胶体上聚集体的聚集中。耗竭相互作用和组合贡献是这些力量的两个重要体现。在探索其势能面底部的系统中，熵也起着主导作用。在斑片状胶体中，粒子与高度各向异性和局部电势相互作用，基态结构通常在能量上退化，剩下的熵决定了热力学稳定的多晶型物。一个惊人的结果是即使在温度消失的情况下，仍可能产生比胶体“晶体”在热力学上更稳定的胶体“液体”。