Polymer-Wall Interactions Slow Infiltration Dynamics in Bicontinuous, Nanoporous Structures

WW Kong and A Neuman and L Moore and DY Lee and RA Riggleman and RJ Composto, MACROMOLECULES, 58, 5058-5070 (2025).

DOI: 10.1021/acs.macromol.4c02326

Polymer infiltration is studied in a bicontinuous nanoporous gold (NPG) scaffold. For poly(2-vinylpyridine) (P2VP) with molecular weights (M w ) ranging from 51k to 940k Da, infiltration is investigated in an NPG with a fixed pore radius (R p = 34 nm) under moderate confinement (Gamma = R g/R p) 0.18 to 0.78. The time for 80% infiltration (tau 80%) scales as M w 1.43, similar to PS, but weaker than the bulk behavior. Infiltration of P2VP is slower than PS due to stronger P2VP-wall interactions resulting in a physisorbed P2VP layer. This interpretation is supported by the similar scaling of tau 80% for P2VP and PS, as well as molecular dynamics (MD) simulations. Simulations show that infiltration time scales as M w 1.4 and that infiltration slows as the polymer-wall attraction increases. As M w increases, the effective viscosity transitions from greater than to less than the bulk viscosity due to pore narrowing and a reduction in entanglement density. These studies provide new insight into polymer behavior under confinement and a new route for preparing nanocomposites at high filler loadings.

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