Enhanced Dynamics of Confined Polymers near the Immiscible Polymer–Polymer Interface: Neutron Reflectivity Studies

Abstract

For polymer-blend films, local dynamics in confined polymer domains tend to differ from the bulk because of significant contributions from the polymer–polymer interface. Herein, we investigated the diffusion dynamics of entangled polymer thin films confined between different polymers in a direction perpendicular to the surface using neutron reflectivity. We found that a bilayer of poly­(methyl methacrylate) (PMMA) and deuterated PMMA (dPMMA) sandwiched between polystyrene (PS) layers exhibited significant increase in mobility near the polymer–polymer interface with decreasing PMMA thickness. This indicates that the contribution of repulsive interactions at the immiscible polymer–polymer interface becomes more significant as the film thickness decreases. We also found that the interfacial roughness between PMMA and PS (28 Å at equilibrium) and soft confinement of PS layers did not significantly affect the change in the diffusion dynamics of the adjacent PMMA. This was evidenced by comparison with the diffusion results of multilayers with a flat interface (8 Å at equilibrium) between PMMA and hard PS by UV cross-linking.

Position-Dependent Diffusion Dynamics of Entangled Polymer Melts Nanoconfined by Parallel Immiscible Polymer Films

“…1 R g away from the PS−PMMA interface. 11 The diffusion dynamics at this position were further accelerated by geometrical confinement, namely, with decreasing thickness of the confined layer. Differently, in this study, the local dynamics were measured by NR as a function of distance from the PS− PMMA interface by changing the thicknesses of PMMA and dPMMA.…”

Local Glass Transition Temperature Tg(z) Within Polystyrene Is Strongly Impacted by the Modulus of the Neighboring PDMS Domain

“…High-performance multicomponent materials have nanostructured morphologies where the desired global properties are obtained from an amalgam of local property changes caused by the multitude of internal interfaces. Studies on thin polymer films have demonstrated a host of property changes with decreasing film thickness attributed to interface effects, − including polymer–polymer interfaces. − The efficient design of multicomponent materials requires the understanding of how these interface effects perturb local properties. Glassy–rubbery interfaces between polymer domains impart material toughness and flexibility , and can be used to tune phononic transport .…”

Local Orientation of Polystyrene at the Interface with Poly(methyl methacrylate) in Block Copolymer

“…Polymer alloys represented by block copolymers (BCPs) and polymer blends are one of the most widely studied areas in the field of polymer science and engineering. − In particular, various studies related to the interface for a phase-separated polymer pair have been conducted from the viewpoint of the miscibility and compatibility. − This is because the interfacial structure is of pivotal importance not only for inherent academic interest but also for cutting-edge industrial applications, such as thin film devices, including next-generation lithography, − in addition to the traditional ones based on mechanical − and optical properties. − Polymer chains change the aggregation states at the interface so as to minimize the interfacial energy, which is one of the controlling factors of the interfacial thickness. Thus, it is crucial to obtain a deeper understanding of the phase-separated polymer interface at the molecular level.…”