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We present neutron spin echo experiments that address the much debated topic of dynamic phenomena in polymer melts that are induced by interacting with a confining surface. We find an anchored surface layer that internally is highly mobile and not glassy as heavily promoted in the literature. The polymer dynamics in confinement is, rather, determined by two phases, one fully equal to the bulk polymer and another that is partly anchored at the surface. By strong topological interaction, this phase confines further chains with no direct contact to the surface. These form the often invoked interphase, where the full chain relaxation is impeded through the interaction with the anchored chains. The investigation of liquids under nanoconfinement has been a topic of intense scientific scrutiny for decades [1]. The issues are glass transition, crystallization, and phase separation under confinement [2,3]. Recently, this interest has been amplified by the rising of nanotechnology that aims to create new properties by modifying materials at the nanoscale. Polymers are of particular interest since they offer a large range of applications such as coatings, lubrication, nanocomposites, and in the field of biological macromolecules, biosensors [4].Close to a confining surface, the conformations of a polymer are significantly restricted [5]. In addition, the interactions with the surface will strongly affect the dynamics. Related issues such as adsorption, friction, network formation, effects on the entanglement density, and polymer density changes under confinement have been studied [6][7][8][9]. The importance of these phenomena thereby depends on the type of polymer, the specificity of the interactions, and the topology of the confinement. In particular, experimental results have been interpreted in terms of the formation of a glassy polymer layer close to surfaces [7]. Furthermore, the existence of an interphase with properties between those of the glassy layer and the bulk has been hypothesized [10][11][12].A large number of experimental studies have focused on nanoparticles dispersed in a polymer matrix. Whereas for noninteracting polymers significant effects only occur at high particle loadings, the addition of nanoparticles that interact with a polymer matrix induces dramatic property changes for the resulting polymer nanocomposite [7,9,10,13,14]. In particular, it has been reported that the interaction between OH groups on the surface of nanoparticles and locally polar poly(ethylene oxide) (PEO) or polydimethylsiloxane (PDMS) chains lead to the formation of a glassy polymer layer [7,10,13]. Theoretical work and computer simulations of chain adsorption as a function of adsorption strength reveal the existence of different chain conformations including trains, loops, and tails [14].Here, we present an investigation on the dynamics of PDMS chains confined in anodic aluminum oxide (AAO) nanopores. We find that PDMS adsorbs at the surface. However, the formed layer is internally highly mobile and not at all glassy. The siz...

The lipid raft hypothesis presents insights into how the cell membrane organizes proteins and lipids to accomplish its many vital functions. Yet basic questions remain about the physical mechanisms that lead to the formation, stability, and size of lipid rafts. As a result, much interest has been generated in the study of systems that contain similar lateral heterogeneities, or domains. In the current work we present an experimental approach that is capable of isolating the bending moduli of lipid domains. This is accomplished using neutron scattering and its unique sensitivity to the isotopes of hydrogen. Combining contrast matching approaches with inelastic neutron scattering, we isolate the bending modulus of ∼13 nm diameter domains residing in 60 nm unilamellar vesicles, whose lipid composition mimics the mammalian plasma membrane outer leaflet. Importantly, the bending modulus of the nanoscopic domains differs from the modulus of the continuous phase surrounding them. From additional structural measurements and all-atom simulations, we also determine that nanoscopic domains are in-register across the bilayer leaflets. Taken together, these results inform a number of theoretical models of domain/raft formation and highlight the fact that mismatches in bending modulus must be accounted for when explaining the emergence of lateral heterogeneities in lipid systems and biological membranes.

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