论文标题
软颗粒与流体界面的解吸能
Desorption energy of soft particles from a fluid interface
论文作者
论文摘要
通过测量其解吸自由能，即从流体界面脱离粒子所需的机械工作，可以检查软颗粒稳定乳液的效率。在这里，我们使用粗粒分子动力学模拟考虑了类似橡胶状的弹性和微凝胶颗粒。通过平均热力学整合方法计算两维配置的解吸能量。结果表明，与刚性颗粒相比，柔软度会影响两个相对方向的粒子界面结合。一方面，与刚性颗粒相比，软粒子在界面处散布在界面上，从而消除了更大的不利液体液体接触面积。另一方面，柔软度为粒子提供了重塑的额外自由度，而不是变形界面，从而导致脱离过程中较小的恢复力。结果表明，第一个效果占上风，因此软球形粒子与刚性球更强烈地连接到流体界面。最后，我们考虑在肿胀和塌陷状态下的微凝胶颗粒。令人惊讶的是，我们发现后者具有较大的结合能。使用热力学参数合理化所有结果，从而为流体界面的软颗粒的解吸能提供了详细的见解。
The efficiency of soft particles to stabilize emulsions is examined by measuring their desorption free energy, i.e., the mechanical work required to detach the particle from a fluid interface. Here, we consider rubber-like elastic as well as microgel particles, using coarse-grained molecular dynamics simulations. The energy of desorption is computed for two and three-dimensional configurations by means of the mean thermodynamic integration method. It is shown that the softness affects the particle-interface binding in two opposing directions as compared to rigid particles. On the one hand, a soft particle spreads at the interface and thereby removes a larger unfavorable liquid-liquid contact area compared to rigid particles. On the other hand, softness provides the particle with an additional degree of freedom to get reshaped instead of deforming the interface, resulting in a smaller restoring force during the detachment. It is shown that the first effect prevails so that a soft spherical particle attaches to the fluid interface more strongly than rigid spheres. Finally, we consider microgel particles both in the swollen and in the collapsed state. Surprisingly, we find that the latter has a larger binding energy. All results are rationalised using thermodynamic arguments and thereby offer detailed insights into the desorption energy of soft particles from fluid interfaces.
