Kinetics of Capillary Rise Infiltration of Statistical and Block Copolymers into Silica Nanoparticle Packings

Capillary rise infiltration (CaRI) enables the preparation of nanocomposites with high nanoparticle loadings and gives insight into the impact of extreme nanoconfinement on the dynamics of polymer transport. Although the polymer-nanoparticle interactions during CaRI have a significant impact, most studies have focused on the effects of confinement on infiltration dynamics and thermomechanical properties of homopolymers. In this study, we investigate the CaRI of statistical and block copolymer infiltrating random packings of silica nanoparticles using in situ ellipsometry. To investigate the effect of varying degrees of polymer-silica surface interactions and monomer sequence, we use poly(styrene-stat-2-vinylpyridine) (S-stat-2VP) statistical copolymers and poly(styrene-b-2-vinylpyridine) (S-b-2VP) block copolymers with different ratio of the two monomers: strongly interacting, 2VP and weakly interacting, S. We observe that both statistical and block copolymers exhibit slower infiltration rates compared to PS and P2VP homopolymers of the same molecular weight. We believe that the conformation of surface-bound chains, resulting from strong 2VP-silica surface interactions, is associated with the observed slow infiltration.