Density Functional Theory for Polymer Phase Separations Induced by Coupling of Chemical Reaction and Elastic Stress

Abstract

A density functional theory is applied to phase separation dynamics influenced by crosslinking reactions in dense polymer solutions. The crosslinking reaction is modeled by a change from non-crosslinked polymers comprising transient network (TN) to crosslinked polymers participating in the percolated permanent network (PN). Deformed TN polymers are considered to relax to the isotropic equilibrium state according to the Maxwellian linear viscoelastic constitutive equation, which is used in the modeling of viscoelastic phase separations. The PN is modeled by a linear elastic constitutive model. When TN polymers are taken into the PN by crosslinking reaction, the instantaneous deformation of the TN polymers are frozen, and such frozen deformations are accumulated as time goes on. A series of simulations is performed using this model, so that two specific features of the viscoelastic and reactive phase separation are obtained, i.e., 1) two-stage phase separation process that leads to a domain structure with two different characteristic length scales, and 2) fixing the phase-separated structure before reaching the macrophase separation.

A Molecular Dynamics Simulation for Thermal Activation Process in Covalent Bond Dissociation of a Crosslinked Thermosetting Polymer

“…In the future, the stress–strain curve over a wide range of system deformations will be quantitatively reproduced by scaling up the system, refining the electrostatic interaction, and other parameters such as , , and the frequency factor in Equation (1). Furthermore, failure mechanisms for various loading conditions, including the cyclic loading for the fatigue failure, will be elucidated on micro to macro scales by combining this approach with coarse-grained simulations such as dissipative particle dynamics [ 57 ], density functional theory [ 58 ], and the finite element method [ 59 ].…”

Reaction-induced morphological transitions in a blend of diblock copolymers and reactive monomers: dissipative particle dynamics simulation

“…These different behaviors are similar to those of reaction-induced viscoelastic phase separation. 40 Fig. 13 depicts the intuitive explanation of the two processes of the connections of cylinders during cross-linking reactions.…”

Modeling Phase Separation of Free-Radical Polymerizations in Crosslinked Networks

“…This model simulated a single-stage polymerization where a mean-field approximation is used to distinguish between the fraction of reacted divinyl monomers that have formed an infinite network and the fraction that remain as free linear chains in the system . Later, Okay coupled thermodynamic equations based on the same Flory–Rehner model with reaction kinetics to determine gel point conversions that affect material properties and ultimately thermodynamic phase separation behavior. , Since then, a variety of models have been produced to simulate phase separation behavior, including density functional theory-based approaches and molecular dynamic simulations. − …”