Mukherjee Biswaroop, Chakrabarti Buddhapriya
Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, U.K.
Macromolecules. 2022 May 24;55(10):3886-3897. doi: 10.1021/acs.macromol.1c02559. Epub 2022 May 12.
We extend the Cahn-Landau-de Gennes mean field theory of wetting in binary mixtures to understand the wetting thermodynamics of a three phase system (e.g., polymer dispersed liquid crystals or polymer-colloid mixtures) that is in contact with an external surface, which prefers one of the phases. Using a model free-energy, which has three minima in its landscape, we show that as the central minimum becomes more stable compared to the remaining ones, the bulk phase diagram encounters a triple point and then bifurcates and we observe a novel non-monotonic dependence of the surface tension as a function of the stability of the central minimum. We show that this non-monotonicity in surface tension is associated with a complete to partial wetting transition. We obtain the complete wetting phase behavior as a function of phase stability and the surface interaction parameters when the system is close to the bulk triple point. The model free-energy that we use is qualitatively similar to that of a renormalized free energy, which arises in the context of polymer-liquid crystal mixtures. Finally, we study the thermodynamics of wetting for an explicit polymer-liquid crystal mixture and show that its thermodynamics is similar to that of our model free-energy.
我们将二元混合物中润湿的Cahn-Landau-de Gennes平均场理论进行扩展，以理解与偏好某一相的外表面接触的三相系统（如聚合物分散液晶或聚合物-胶体混合物）的润湿热力学。使用一个在其能量景观中有三个极小值的模型自由能，我们表明，与其余极小值相比，当中心极小值变得更稳定时，体相图会遇到一个三相点，然后发生分叉，并且我们观察到表面张力作为中心极小值稳定性的函数呈现出一种新颖的非单调依赖性。我们表明，表面张力的这种非单调性与完全润湿到部分润湿的转变相关。当系统接近体相三相点时，我们得到了作为相稳定性和表面相互作用参数函数的完全润湿相行为。我们使用的模型自由能在定性上类似于在聚合物-液晶混合物背景下出现的重整化自由能。最后，我们研究了一种明确的聚合物-液晶混合物的润湿热力学，并表明其热力学与我们的模型自由能相似。
