Experimental Study of the Influence of Periodic Boundary Conditions: Effects of Finite Size and Faster Cooling Rates on Dissimilar Polymer-Polymer Interfaces

Building on our recent work that mapped the profile in local glass transition temperature T-g(z) across a single polystyrene (PS)/poly(n-butyl methacrylate) (PnBMA) interface, we explore the impact of limiting domain size and increasing cooling rate. This study is motivated by traditional computational approaches employed to overcome computer power limitations, extrapolating short time scales and using periodic boundary conditions that introduce repeating interfaces. Using a localized fluorescence method, we find addition of a second PS/PnBMA interface perturbs the local PS Tg(z) at a distance of z = 100 nm from the first interface when the second interface approaches a distance closer than 300 nm. The local Tg(z) profile across a finite PS domain size of 300 nm for a range of cooling rates shows that limiting domain size and increasing cooling rate (faster time scales) diminishes and truncates the broad asymmetric Tg(z) profile, weakening the confinement effect for dissimilar polymer polymer interfaces, consistent with previous studies on single-layer polymer films.