The long-range interface correlation in thin polymer films (polystyrene and fully brominated polystyrene) prepared by spin-coating is examined. Using diffuse X-ray scattering at small angles of incidence, the roughness correlation which dominates the surface morphology of the polymer film is probed from mesoscopic down to molecular in-plane distances. At the smallest replicable in-plane length scale, the crossover from a conformal to a statistically independent roughness spectrum is determined. The influences of molecular weight and film thickness are discussed. Compared to annealed samples, the as-prepared ones show a different scaling behavior, which is explained with simple models taking surface-bending rigidity into account. With a real-time annealing investigation, the decay of interface correlation after the onset of annealing has been followed. At annealing even below the glass-transition temperature, the roughness correlation is changing and disappears during sufficiently long annealing in the melt. Monitoring the changes with time probes the mobility of the polymer molecules at the polymer−vacuum interface. In thin films, the time constant is increased. The determined surface diffusion coefficient shows a slowing down as compared to the bulk behavior which may be attributed to the attractive, long-range substrate−interface interaction.

Polymers with both soluble and insoluble blocks typically self-assemble into micelles, which are aggregates of a finite number of polymers where the soluble blocks shield the insoluble ones from contact with the solvent. Upon increasing concentration, these micelles often form gels that exhibit crystalline order in many systems. In this paper, we present a study of both the dynamics and the equilibrium properties of micellar crystals of triblock polymers using molecular dynamics simulations. Our results show that equilibration of single micelle degrees of freedom and crystal formation occur by polymer transfer between micelles, a process that is described by transition state theory. Near the disordered (or melting) transition, bcc lattices are favored for all triblocks studied. Lattices with fcc ordering are also found but only at lower kinetic temperatures and for triblocks with short hydrophilic blocks. Our results lead to a number of theoretical considerations and suggest a range of implications to experimental systems with a particular emphasis on Pluronic polymers.

We extend the generalized Langevin equation (GLE) method [L. Stella, C. D. Lorenz, and L. Kantorovich, Phys. Rev. B 89, 134303 (2014)] to model a central classical region connected to two realistic thermal baths at two different temperatures. In such nonequilibrium conditions a heat flow is established, via the central system, in between the two baths. The GLE-2B (GLE two baths) scheme permits us to have a realistic description of both the dissipative central system and its surrounding baths. Following the original GLE approach, the extended Langevin dynamics scheme is modified to take into account two sets of auxiliary degrees of freedom corresponding to the mapping of the vibrational properties of each bath. These auxiliary variables are then used to solve the non-Markovian dissipative dynamics of the central region. The resulting algorithm is used to study a model of a short Al nanowire connected to two baths. The results of the simulations using the GLE-2B approach are compared to the results of other simulations that were carried out using standard thermostatting approaches (based on Markovian Langevin and Nosé-Hoover thermostats). We concentrate on the steady-state regime and study the establishment of a local temperature profile within the system. The conditions for obtaining a flat profile or a temperature gradient are examined in detail, in agreement with earlier studies. The results show that the GLE-2B approach is able to treat, within a single scheme, two widely different thermal transport regimes, i.e., ballistic systems, with no temperature gradient, and diffusive systems with a temperature gradient.

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