Mysona Joshua A, McCormick Alon V, Morse David C
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Phys Rev E. 2020 Aug;102(2-1):022605. doi: 10.1103/PhysRevE.102.022605.
Monte Carlo simulations are used to study adsorption of highly asymmetric diblock copolymers to a polymer-polymer interface, and the results compared to self-consistent field theory (SCFT) predictions. The simulation model used here is a bead-spring model that has been used previously to study equilibrium and kinetic properties of spherical micelles [J. A. Mysona et al., Phys. Rev. E 100, 012602 (2019)2470-004510.1103/PhysRevE.100.012602; Phys. Rev. E 100, 012603 (2019)10.1103/PhysRevE.100.012603; Phys. Rev. Lett. 123, 038003 (2019)10.1103/PhysRevLett.123.038003]. Interfacial copolymer concentration Γ and interfacial tension γ are measured as functions of bulk copolymer concentration at concentrations up to the critical micelle concentration over a range of values of the Flory-Huggins χ parameter. The dependence of interfacial pressure Π = γ_{0}-γ on Γ (where γ_{0} is the interfacial tension in the absence of copolymer) is found to be almost independent of χ and to be accurately predicted by SCFT. The bare interfacial tension γ_{0} and total interfacial tension γ(Γ) can also be accurately predicted by SCFT using an estimate of χ obtained from independent analysis of properties of symmetric diblock copolymer melts. SCFT predictions obtained with this estimate of χ do not, however, adequately describe the thermodynamics of the coexisting bulk copolymer solution, as a result of contraction of the strongly interacting core block of dissolved copolymers. Accurate predictions of the relationship between bulk and interfacial properties can thus only be obtained for this system by combining SCFT predictions of the interfacial equation of state with a fit to the measured equation of state for the bulk solution.
蒙特卡罗模拟用于研究高度不对称二嵌段共聚物在聚合物 - 聚合物界面的吸附，并将结果与自洽场理论（SCFT）预测进行比较。这里使用的模拟模型是一个珠簧模型，该模型先前已用于研究球形胶束的平衡和动力学性质[J. A. Mysona等人，《物理评论E》100, 012602 (2019)2470 - 004510.1103/PhysRevE.100.012602；《物理评论E》100, 012603 (2019)10.1103/PhysRevE.100.012603；《物理评论快报》123, 038003 (2019)10.1103/PhysRevLett.123.038003]。在一系列弗洛里 - 哈金斯χ参数值下，测量了界面共聚物浓度Γ和界面张力γ随本体共聚物浓度的变化，直至临界胶束浓度。发现界面压力Π = γ₀ - γ对Γ的依赖性（其中γ₀是不存在共聚物时的界面张力）几乎与χ无关，并且SCFT能准确预测。通过对对称二嵌段共聚物熔体性质的独立分析获得χ的估计值，SCFT也能准确预测裸界面张力γ₀和总界面张力γ(Γ)。然而，由于溶解共聚物的强相互作用核心嵌段收缩，用此χ估计值获得的SCFT预测不能充分描述共存本体共聚物溶液的热力学。因此，对于该系统，只有将界面状态方程的SCFT预测与对本体溶液测量状态方程的拟合相结合，才能准确预测本体和界面性质之间的关系。
