Martens C M, van Leuken S H M, Opdam J, Vis M, Tuinier R
Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Phys Chem Chem Phys. 2022 Feb 9;24(6):3618-3631. doi: 10.1039/d1cp05026e.
We derive a simple, yet accurate approximate mean-field expression for the depletion thickness of a solution of dilute semi-flexible polymers next to a hard surface. In the case of a hard wall this equation has the simple form = [1 - tanh(/)], where accounts for the degree of flexibility and is the depletion thickness in the case of fully flexible polymers. For fixed polymer coil size, increasing the chain stiffness leads to a decrease in the depletion thickness. The approach is also extended to include higher polymer concentrations in the semidilute regime. The analytical expressions are in quantitative agreement with numerical self-consistent field computations. A remarkable finding is that there is a maximum in the depletion thickness as a function of the chain stiffness in the semidilute concentration regime. This also means that depletion attractions between colloidal particles reach a maximum for a certain chain stiffness, which may have important implications for the phase stability of colloid-polymer mixtures. The derived equations could be useful for the description of interactions in- and phase stability of mixtures of colloids and semi-flexible polymers.
我们推导了一个简单而准确的近似平均场表达式，用于描述稀溶液中半柔性聚合物靠近硬表面时的耗尽层厚度。对于硬壁情况，该方程具有简单形式 = [1 - tanh(/)], 其中 表示柔性程度， 是完全柔性聚合物情况下的耗尽层厚度。对于固定的聚合物线团尺寸，增加链的刚性会导致耗尽层厚度减小。该方法还扩展到包括半稀溶液区域中更高的聚合物浓度。解析表达式与数值自洽场计算结果在定量上一致。一个显著的发现是，在半稀溶液浓度区域中，耗尽层厚度作为链刚性的函数存在一个最大值。这也意味着，对于特定的链刚性，胶体颗粒之间的耗尽吸引力达到最大值，这可能对胶体 - 聚合物混合物的相稳定性具有重要意义。所推导的方程对于描述胶体和半柔性聚合物混合物中的相互作用及相稳定性可能是有用的。
