In order to improve the biological performance of synthetic polymers and to enhance the mechanical characteristics by tailoring the permeability properties of biopolymers, a new class of specifically designed materials (bioartificial polymeric materials), consisting of blends of synthetic polymers and biopolymers, has been recently introduced. In this work we present a computational method based on molecular mechanics (MM) and dynamics (MD) techniques, to investigate their permeability to small molecules. The permeability properties was assessed of poly(vinyl alcohol)-(PVA)- dextran-(Dex) and poly(acrylic acid)-(PAA)-Dex membranes with different blend composition. Amorphous bulk models of PVA–Dex and PAA–Dex mixtures with 80:20, 60:40, 40:60 (w/w) ratios were generated. Two steps have been performed iteratively, the former using a MM simulation for equilibration and the latter using MD simulations for model refinement. Virtual uniaxial traction tests were performed, adopting the Second Derivative (SD) procedure, in order to assess the mechanical behavior of the bulk models. The diffusion coefficients for H2O were determined via NVT molecular dynamics simulations. Using the data of the motion of water inside the bulk models, the diffusivity constant was calculated applying the Einstein equation. Correlation of diffusion coefficients with free volume, was found. The results of the simulations agree with theoretical considerations: as the content of dextran increases from 80:20 to 40:60 a 86 % decrease of the diffusion constant is obtained and the values (range 0.14–56.5 10−6 cm2s−1) have the order of magnitude expected, and similar on the diffusion of small molecules in amorphous polymeric membranes.

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