Slow Kinetics of Confined Diblock Copolymer upon Infiltration into a Bicontinuous, Nanoporous Gold Scaffold

Advantageous properties such as reduced viscosity and increased strength prevail in systems in which polymer chain dimensions are perturbed by a rigid structure. In this study, the effect of polymer architecture on diffusion of a model diblock copolymer confined to a nanoporous gold scaffold is investigated using in-situ ellipsometry. Delays up to an order of magnitude in block copolymer infiltration signal intense unfavorability across temperatures, and the kinetic law of the diblock copolymer scales with the 4^th root of time instead of the square root as previously predicted. TEM imaging suggests that polymer chains crowd near the walls of the scaffold and are less dense in the center of the pore. Additionally, preferential adherence of a bound layer of homopolymer to the substrate produces less dramatic delays than block copolymer morphology and varies with the polymer film thickness prior to infiltration. The cylindrical morphology of the diblock copolymer prior to infiltration is proposed as an explanation for the delayed kinetics; connections to fields which employ high surface area materials such as separations or carbon capture are drawn and pathways to achieving fast assembly of high molecular weight polymer nanocomposites are generalized to other systems.