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Form fluctuations of microemulsion droplets are observed in experiments using dielectric spectroscopy (DS) and neutron spin echo spectroscopy (NSE). Previous work on dioctyl sodium sulfosuccinate based water in oil microemulsions in the droplet phase has shown that adding a water soluble polymer (Polyethylene glycol M = 1500 g mol-1) modifies these fluctuations. While for small droplet sizes (water core radius rc < 37 Å) compared to the size of the polymer both methods consistently showed a reduction in the bending modulus of the surfactant shell as a result of polymer addition, dielectric spectroscopy suggests the opposite behaviour for large droplets. This observation is now confirmed by NSE experiments on large droplets. Structural changes due to polymer addition are qualitatively independent of droplet size. Dynamical properties, however, display a clear variation with the number of polymer chains per droplet, leading to the observed changes in the bending modulus. Furthermore, the contribution of structural and dynamical properties on the changes in bending modulus shifts in weight. With increasing droplet size, we initially find dominating finite size effects and a changeover to a system, where interactions between the confined polymer and the surfactant shell dominate the bending modulus. [ABSTRACT FROM AUTHOR]

We combine 2H nuclear magnetic resonance (NMR), broadband dielectric spectroscopy (BDS), and triplet solvation dynamics (TSD) to investigate molecular dynamics in glass-forming mixtures of water and propylene glycol in very broad time and temperature ranges. All methods yield consistent results for the α process of the studied mixtures, which hardly depends on the composition and shows Vogel-Fulcher temperature dependence as well as Cole-Davidson spectral shape. The good agreement between BDS and TDS data reveals that preferential solvation of dye molecules in microheterogeneous mixtures does not play an important role. Below the glass transition temperature Tg, NMR and BDS studies reveal that the β process of the mixtures shows correlation times, which depend on the water concentration, but exhibit a common temperature dependence, obeying an Arrhenius law with an activation energy of Ea = 0.54 eV, as previously reported for mixtures of water with various molecular species. Detailed comparison of NMR and BDS correlation functions for the β process unravels that the former decay faster and more stretched than the latter. Moreover, the present NMR data imply that propylene glycol participates in the β process and, hence, it is not a pure water process, and that the mechanism for molecular dynamics underlying the β process differs in mixtures of water with small and large molecules. [ABSTRACT FROM AUTHOR]

Water dependent secondary relaxations are well known in glass formers. In Poly(&eh;-caprolactone) (PCL) both the dielectric and mechanical β-relaxation have a water dependent relaxation strength, whose molecular reasons are still unclear. By systematically varying the water content of the samples, a linear dependency between the dielectric relaxation strength and the number of absorbed water molecules was found, leading to a vanishing relaxation for completely dried samples. Neither the α-relaxation nor the secondary β-relaxation showed water dependent relaxation times and also the glass transition temperature determined by differential scanning microscopy (DSC) is not affected by the water absorption. So far the molecular origins of the dielectric β-relaxation in PCL are not consistent with the observations in other glass formers. [ABSTRACT FROM AUTHOR]

We present results of in situ measurements of the filling process of polymer melts in nanopores. After accurate characterization of the empty nanopores, they are filled with the hydrophobic polyisobutylene and the hydrophilic poly-ε-caprolactone. The filling process is investigated in situ with small angle x-ray scattering. The time-dependent scattering intensity is investigated with a model function based on the Lucas–Washburn equation for the filling process of liquids in cylindrical pores. The model function describes the data qualitatively well in terms of a t-dependency of the filling height, but deviates clearly from the expected quantitative values of the bulk material properties. Furthermore, the occurrence of a precursor film wetting the nanopore surface on a short time scale is observed. [ABSTRACT FROM AUTHOR]

Studies the structure and segmental dynamics of liquid crystalline block and diblock copolymers. Key issues of interest; Analysis of pertinent topics and relevant issues; Implications on Chinese studies of polymer science.

We have performed inelastic neutron scattering experiments on protonated and fully deuterated partially crystalline polyethylene. Using a high-resolution, three-axes spectrometer with an energy resolution of 80 μeV, it was possible to detect a quasielastic process in the dynamic structure factor with a FWHM of 0.3 meV. This process was shown to be active above T=260 K and its FWHM was nearly independent of temperature and scattering vector. The spatial extent of the underlying motional process was displacement increases strongly with T above T up to 4 Å at T=380 K. Comparison with results from similar work on fully amorphous polymers suggests to relate T to the glass transition of the amorphous phase in partially crystalline polyethylene. The coherent structure factor showns no evidence for a significant contribution of correlated motion to the process. A speculative explanation of the observed phenomenon as a non-equilibrium soft-mode is proposed. [ABSTRACT FROM AUTHOR]