Interdiffusion of solvent into glassy polymer films: a molecular dynamics study.

Area of Science:

• Polymer Science
• Materials Science
• Computational Chemistry

Background:

• Understanding solvent diffusion in polymers is crucial for material design.
• Polymer properties change significantly between melt and glassy states, affecting diffusion.

Purpose of the Study:

• To investigate solvent interdiffusion into entangled polymer matrices.
• To analyze how polymer state (melt vs. glass) influences diffusion behavior.
• To compare different methods for calculating solvent diffusivity.

Main Methods:

• Large-scale molecular dynamics simulations.
• Grand canonical Monte Carlo simulations.
• Analysis using Fick's model and the Darken equation.

Main Results:

• Solvent diffusion follows Fickian behavior (weight gain proportional to t(1/2)).
• Diffusivity is highly concentration-dependent, especially near the glass transition temperature.
• Fick's model and Darken equation yield comparable diffusivity values.

Conclusions:

• The polymer's state (melt or glass) significantly impacts solvent diffusivity.
• Solvent concentration profiles are key to understanding diffusion behavior.
• Simulation methods provide consistent results for solvent-polymer systems.