Fig. 5: Molecular dynamic simulations.

a, b Surface electrostatic potential distributions of NaAlg and PDDA monomers. c, d Molecular structures of pure NaAlg, pure PDDA, and PDDA/NaAlg complex (blue chains represent NaAlg and cyan chains represent PDDA). Equilibrium structures of PDDA/NaAlg system (e) and pure NaAlg (f). g Simulated pore size distributions in the equilibrium structures shown in (e) and (f). h, i Visualization of free volume in the PDDA/NaAlg and pure NaAlg systems (blue and gray zones represent the pore and polymer chain domains, respectively). Free volume fractions (j) and mean square displacements (k) of the PDDA/NaAlg and pure NaAlg systems.