Taming the Strength of Interfacial Interactions via Nanoconfinement

Abstract

The interaction between two immiscible materials is related to the number of contacts per unit area formed by the two materials. For practical reasons, this information is often parametrized by the interfacial free energy, which is commonly derived via rather cumbersome approaches, where properties of the interface are described by combining surface parameters of the single materials. These combining rules, however, neglect any effect that geometry might have on the strength of the interfacial interaction. In this Article, we demonstrate that the number of contacts at the interface between a thin polymer coating and its supporting substrate is altered upon confinement at the nanoscale level. We show that explicitly considering the effect of nanoconfinement on the interfacial potential allows a quantitative prediction of how sample geometry affects the number of contacts formed at the interface between two materials.

Revealing Interfacial Interactions in Random Copolymer Adsorbed Layers by Solvent Leaching

“…Through these relationships, the partial desorption of copolymer adsorbed layers in the presence of hydrogen‐bonding solvents can grant valuable insight into polymer‐substrate interactions, since the relative change to copolymer h ads with washing reflects a corresponding change to its number of individual contacts with the substrate. The evidence that the number of polymer‐substrate adsorbed contacts is influenced by the film's surrounding environment is consistent with the work of Simavilla et al, which related the change in number of contacts and thickness resulting of adsorbed layers to system‐specific effective Hamaker constants 33…”

“…Predictions by Guiselin32 and supporting experiments20,33 have demonstrated that h ads of a given polymer is directly proportional to its number of monomers directly and indirectly adsorbed to the substrate, both of which scale with N 1/2 , where N is the polymer's degree of polymerization. This adsorbed amount, for a given polymer and molecular weight, is then directly proportional to the quantity of individual contacts at the substrate 33.…”

“…Predictions by Guiselin32 and supporting experiments20,33 have demonstrated that h ads of a given polymer is directly proportional to its number of monomers directly and indirectly adsorbed to the substrate, both of which scale with N 1/2 , where N is the polymer's degree of polymerization. This adsorbed amount, for a given polymer and molecular weight, is then directly proportional to the quantity of individual contacts at the substrate 33. The proportionality between h ads , adsorbed amount, and polymer‐substrate contacts differs with composition and molecular weight due to different adsorbed layer structures,24 so these relationships can only be applied when comparing adsorbed layers of the same polymer.…”

“…This adsorbed amount, for a given polymer and molecular weight, is then directly proportional to the quantity of individual contacts at the substrate. [33] The proportionality between h ads , adsorbed amount, and polymer-substrate contacts differs with composition and molecular weight due to different adsorbed layer structures, [24] so these relationships can only be applied when comparing adsorbed layers of the same polymer. Through these relationships, the partial desorption of copolymer adsorbed layers in the presence of hydrogen-bonding solvents can grant valuable insight into polymer-substrate interactions, since the relative change to copolymer h ads with washing reflects a corresponding change to its number of individual contacts with the substrate.…”

“…The evidence that the number of polymer-substrate adsorbed contacts is influenced by the film's surrounding environment is consistent with the work of Simavilla et al, which related the change in number of contacts and thickness resulting of adsorbed layers to system-specific effective Hamaker constants. [33] Extending the desorption behaviors of PS (no desorption) and PMMA (complete desorption) to those of P(S-r-MMA) yields a simplified model for solvent leaching wherein all MMA contacts desorb and all S segments remain adsorbed on the substrate. As such, the relative drop in h ads for each copolymer (Figure 3), which is proportional to the relative loss of adsorbed chains, provides an indirect measure of the composition of individually adsorbed segments.…”