Interdiffusion of solvent into glassy polymer films: A molecular dynamics study

Abstract

Large scale molecular dynamics and grand canonical Monte Carlo simulation techniques are used to study the behavior of the interdiffusion of a solvent into an entangled polymer matrix as the state of the polymer changes from a melt to a glass. The weight gain by the polymer increases with time t as t 1/2 in agreement with Fickian diffusion for all cases studied, although the diffusivity is found to be strongly concentration dependent especially as one approaches the glass transition temperature of the polymer. The diffusivity as a function of solvent concentration determined using the one-dimensional Fick's model of the diffusion equation is compared to the diffusivity calculated using the Darken equation from simulations of equilibrated solvent-polymer solutions. The diffusivity calculated using these two different approaches are in good agreement.The behavior of the diffusivity strongly depends on the state of the polymer and is related to the shape of the solvent concentration profile. * mtsige@sandia.gov † gsgrest@sandia.gov

Generalized model for the diffusion of solvents in glassy polymers: From Fickian to Super Case II

“…However, only the relative magnitudes of the diffusion coefficients determine the diffusion type, while their absolute magnitudes only influence the time scale at which diffusion takes place. The present analysis pro-vides an overview that incorporates the many specialized models interpreting specific types of diffusion 3,4,[28][29][30] into one unified model.…”

Colloidal permeability of liquid membranes consisting of hard particles by nonequilibrium simulations

“…6,7 In fluid membranes, on the other hand, the membrane has internal dynamics as well as attractive interactions or a ligand that prevents the membrane from breaking apart-so called tethered membranes. 16,17 Again, Fickian diffusion with constant diffusion coefficient is found from the weight gain in the control volume initially occupied by the polymer. Without these carriers, permeation relies on the diffusion of the feed into the membrane, which is generally denser.…”

“…[11][12][13][14] In these cases, the pore size is not constant and depends on the concentration fluctuations, 15 but also transport is aided by specific interactions with some components of the membrane ͑called carri-ers͒. 17 In this work both ideas are brought together: we study the transport across a particulate fluid membrane. Diffusion into a dense matrix has been studied, e.g., modeling the matrix as a polymer system.…”

Binding affinity between small molecules in solvent and polymer film using molecular dynamics simulations

“…With an appropriate interaction potential, MD simulations can predict many thermodynamics and transport properties of small molecules in a polymeric film such as the solubility parameter [13][14][15], the partition coefficient [16,17] and the diffusion coefficient [18][19][20]. In MD simulations, the prediction of binding affinity between two components is characterized through the solubility parameter ı.…”