A phase field model for dynamic simulations of reactive blending of polymers
A phase field model for dynamic simulations of reactive blending of polymers
复制标题
聚合物反应共混动态模拟的相场模型
DOI：
10.1039/d1sm01686e
复制
发表时间：
2022
期刊：
影响因子：
3.4
通讯作者：
Fredrickson, Glenn H.
中科院分区：
文献类型：
--
作者：
Tikekar, Mukul D.;Delaney, Kris T.;Villet, Michael C.;Tree, Douglas R.;Fredrickson, Glenn H.
生成不混溶聚合物的增容共混物的简便方法是通过末端官能化的均聚物的反应性共混。取决于端基，反应可以是可逆的或不可逆的，并且受反应物均聚物和相容共聚物产物的不相容性和输送的影响。在这里，我们描述了一个相场框架来模拟反应动力学，扩散和多组分热力学的微观结构和反应速率在反应共混的演变的组合动力学。一个密度泛函没有拟合参数，这是通过调整Uneyama和土井的框架，并定性地同意自洽场理论，在扩散动力学模型中使用。对于等长反应性聚合物以等比例混合的对称混合物，我们发现，取决于Flory χ参数，不可逆反应共混物的微观结构通过丰富的形态演变而进展，包括从两相共存到均匀混合物，或从两相共存到三相共存过渡到均匀共混物或层状共聚物。在高χ下三相区域的出现导致了以前未报道的反应速率缩放。对于可逆反应，我们发现平衡组成是反应平衡常数和χ参数的函数。我们表明，相场模型是一种有效的方法来了解复杂的相互作用的热力学和动力学的影响，在反应的聚合物共混物。
A facile way to generate compatibilized blends of immiscible polymers is through reactive blending of end-functionalized homopolymers. The reaction may be reversible or irreversible depending on the end-groups and is affected by the immiscibility and transport of the reactant homopolymers and the compatibilizing copolymer product. Here we describe a phase-field framework to model the combined dynamics of reaction kinetics, diffusion, and multi-component thermodynamics on the evolution of the microstructure and reaction rate in reactive blending. A density functional with no fitting parameters, which is obtained by adapting a framework of Uneyama and Doi and qualitatively agrees with self-consistent field theory, is used in a diffusive dynamics model. For a symmetric mixture of equal-length reactive polymers mixed in equal proportions, we find that depending on the Flory χ parameter, the microstructure of an irreversibly reacting blend progresses through a rich evolution of morphologies, including from two-phase coexistence to a homogeneous mixture, or a two-phase to three-phase coexistence transitioning to a homogeneous blend or a lamellar copolymer. The emergence of a three-phase region at high χ leads to a previously unreported reaction rate scaling. For a reversible reaction, we find that the equilibrium composition is a function of both the equilibrium constant for the reaction and the χ parameter. We demonstrate that phase-field models are an effective way to understand the complex interplay of thermodynamic and kinetic effects in a reacting polymer blend.