Modeling polymeric gels: The role of chain fexibility on the structure of physical gels

Abstract

Abstract. Using molecular dynamics simulations and a simple model for chain molecules we study the gel formation under different conditions. The main characteristic of the model is the short attractive range of the non-bonding interaction, which leads to the formation of a single percolated cluster trapped in long lived metastable state that resemble the properties of polymeric physical gels. The gels are formed by imposing a sudden quenching on well equilibrated high temperature conformations. In particular, we investigated the effect of concentration and polymer persistence length on the resulting percolated structures. Using a Monte Carlo approach, we characterize the size of the cavities that develop inside the bulk of the gels. The results show that polymers with higher persistence length produce gel structures with smaller cavities.

Molecular dynamics study of polymeric chemical gels: Effect of persistence length and crosslinker density

“…The simulation methodology used for the present study is based on our previous study for polymeric physical gels . The polymer molecules are represented by a chain of N beads (monomers) connected with a FENE potential.…”

“…As is customary in simulation of coarse‐grained model systems, we use reduced units to describe all the interactions, following our previous work . Then, r 0 = 1, σ = 0.1, and ɛ = 1.…”

“…We performed simulations for molecules having different rigidity, as in ref. by changing the strength of the harmonic angular potential K θ . The persistence length ( λ ) of the isolated and un‐reactive molecules is related to the angular potential by λ = 4499 K θ + 0.8568.…”

“…In previous works, we have studied the formation of physical gels of colloidal particles, and polymer molecules using computer simulations. In the formation of physical gels, the attractive range of the nonbonding potential relative to the size of the particles or molecules is an important factor that affects the properties of the gel state: short attractive range leads to more stable physical gels .…”

“…For polymeric physical gels, we studied the formation of a percolated cluster upon a sudden quenching imposed on the initial well‐mixed polymer solution. The effect of the persistence length of the chains on the resulting percolated structures was investigated . It was found that polymers with higher persistence length produce gel structures with smaller cavities.…”