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Dynamics and structures of protic ionic liquids from the superbase guanidinium are analyzed in detail. The H-bond strength correlates with the proton affinity of the constituting acid and can be monitored by the 1H or 15N chemical shifts.

A general approach for super-H-shaped block copolymers based on bifunctional carbanionic polymerization, epoxide termination and lactone ROP is introduced. TEM and SAXS confirmed microphase separation of (PLLA)3-b-PI-b-(PLLA)3 triblock structures.

The organization of plasmonic nanoparticles (NPs) determines the strength and polarization dependence of coupling of their surface plasmons. In this study, plasmon coupling of spherical Au NPs with...

We report on the dilution-induced agglomeration of ultrathin gold nanowires (AuNWs) into regular bundles. Wires with a metal core diameter of 1.6–1.7 nm surrounded by a ligand shell of oleylamine f...

The controlled agglomeration of superparamagnetic iron oxide nanoparticles (SPIONs) was used to rapidly switch their magnetic properties. Small-angle X-ray scattering (SAXS) and dynamic light scattering showed that tailored iron oxide nanoparticles with phase-changing organic ligand shells agglomerate at temperatures between 5 °C and 20 °C. We observed the concurrent change in magnetic properties using magnetic particle spectroscopy (MPS) with a temporal resolution on the order of seconds and found reversible switching of magnetic properties of SPIONs by changing their agglomeration state. The non-linear correlation between magnetization amplitude from MPS and agglomeration degree from SAXS data indicated that the agglomerates' size distribution affected magnetic properties.

Non-polar magnetic nanoparticles agglomerate upon cooling. This process is followed by in situ small angle X-ray scattering to assess structural properties of the emerging agglomerates. On the length scale of a few particle diameters, no differences are found between the agglomerates of small (d = 12 nm) and large (d = 22 nm) nanoparticles. Hard-sphere like random packing with a local packing fraction of η = 0.4 is seen. On larger length scales, small particles form compact superstructures, while large particles arrange into agglomerates that resemble chain-like structures in SAXS. This can be explained by directed magnetic dipole interactions that dominate larger particles, while isotropic van der Waals interaction governs the agglomeration of smaller particles.

Gravity affects colloidal dispersions via sedimentation and convection. We used dynamic light scattering (DLS) to quantify the mobility of nanoparticles on ground and in microgravity. A DLS instrument was adapted to withstand the accelerations in a drop tower, and a liquid handling set-up was connected in order to stabilize the liquid temperature and enable rapid cooling or heating. Light scattering experiments were performed in the drop tower at ZARM (Bremen, Germany) during a microgravity interval of 9.1 s and compared to measurements on ground. Particle dynamics were analyzed at constant temperature and after a rapid temperature drop using a series of DLS measurements with 1 s integration time. We observed nanoparticles with average gold core diameters of 7.8 nm and non-polar oleylamine shells that were dispersed in tetradecane and had an average hydrodynamic diameter of 21 nm. The particles did not change their diameter in the observed temperature range. The particle dynamics inferred from DLS on ground and in microgravity were in good agreement, demonstrating the possibility to perform reliable DLS measurements in a drop tower.

Self-assembly of nanoscale structures at liquid–solid interfaces occurs in a broad range of industrial processes and is found in various phenomena in nature. Conventional theory assumes spherical particles and homogeneous surfaces, but that model is oversimplified, and nanoscale in situ observations are needed for a more complete understanding. Liquid-phase scanning transmission electron microscopy (LP-STEM) is used to examine the interactions that direct the self-assembly of superlattices formed by gold nanoparticles (AuNPs) in nonpolar liquids. Varying the molecular coating of the substrate modulates short-range attraction and leads to switching between a range of different geometric structures, including hexagonal close-packed (hcp), simple hexagonal (sh), dodecahedral quasi-crystal (dqc), and body-centered cubic (bcc) lattices, as well as random distributions. Langevin dynamics simulations explain the experimental results in terms of the interplay between nanoparticle faceting, ligand shell structure, and substrate–NP interactions.

Ionic liquids are modern liquid materials with potential and actual implementation in many advanced technologies. They combine many favourable and modifiable properties but have a major inherent drawback compared to molecular liquids – slower dynamics. In previous studies we found that the dynamics of ionic liquids are significantly accelerated by the introduction of multiple ether side chains into the cations. However, the origin of the improved transport properties, whether as a result of the altered cation conformation or due to the absence of nanostructuring within the liquid as a result of the higher polarity of the ether chains, remained to be clarified. Therefore, we prepared two novel sets of methylammonium based ionic liquids; one set with three ether substituents and another set with three butyl side chains, in order to compare their dynamic properties and liquid structures. Using a range of anions, we show that the dynamics of the ether-substituted cations are systematically and distinctly accelerated. Liquefaction temperatures are lowered and fragilities increased, while at the same time cation–anion distances are slightly larger for the alkylated samples. Furthermore, pronounced liquid nanostructures were not observed. Molecular dynamics simulations demonstrate that the origin of the altered properties of the ether substituted ionic liquids is primarily due to a curled ether chain conformation, in contrast to the alkylated cations where the alkyl chains retain a linear conformation. Thus, the observed structure–property relations can be explained by changes in the geometric shape of the cations, rather than by the absence of a liquid nanostructure. Application of quantum chemical calculations to a simplified model system revealed that intramolecular hydrogen-bonding is responsible for approximately half of the stabilisation of the curled ether-cations, whereas the other half stems from non-specific long-range interactions. These findings give more detailed insights into the structure–property relations of ionic liquids and will guide the development of ionic liquids that do not suffer from slow dynamics.

Mixtures of water and PEG exhibit a well known eutectic phase diagram. While the thermodynamic properties like eutectic and liquidus temperatures as well as the eutectic concentration are intensely investigated almost nothing is known about the structural properties of water and PEG in the different regions of the phase diagram. Therefore, we report on a combined DSC, SAXS and WAXS study over the full range of polymer water compositions in order to elucidate the crystalline and semi-crystalline structure. Throughout the whole phase diagram no signatures of a mixed-crystalline phase of PEG and water can be found. Below the eutectic temperature, both components demix microscopically into hexagonal ice and crystalline PEG with its well known crystalline structure. In the region between eutectic and liquidus temperature, the solid component is composed of a single phase of either pure semi-crystalline PEG (PEG rich side of the phase diagram) or pure ice (water rich side). The semi-crystalline structure of PEG, in contrast, is changed by the presence of water. Its long spacing dac increases due to the incorporation of water molecules in the amorphous regions, while the formation of crystalline regions seems to be enhanced, resulting in an almost unaffected crystallinity.

Gravity can affect the agglomeration of nanoparticles by changing convection and sedimentation. The temperature-induced agglomeration of hexadecanethiol-capped gold nanoparticles in microgravity (µ g) is studied at the ZARM (Center of Applied Space Technology and Microgravity) drop tower and compared to their agglomeration on the ground (1 g). Nonpolar nanoparticles with a hydrodynamic diameter of 13 nm are dispersed in tetradecane, rapidly cooled from 70 to 10 °C to induce agglomeration, and observed by dynamic light scattering at a time resolution of 1 s. The mean hydrodynamic diameters of the agglomerates formed after 8 s in microgravity are 3 times (for low initial concentrations) to 5 times (at high initial concentrations) larger than on the ground. The observations are consistent with an agglomeration process that is closer to the reaction limit on thground and closer to the diffusion limit in microgravity.

A new type of hybrid core-shell nanoparticle dielectric that is suitable for inkjet printing is introduced. Gold cores (dcore ≈ 4.5 nm diameter) are covalently grafted with thiol-terminated polystyrene (Mn = 11000 Da and Mn = 5000 Da) and used as inks to spin-coat and inkjet-print dielectric films. The dielectric layers have metal volume fractions of 5 to 21 vol% with either random or face-centered-cubic structures depending on the polymer length and grafting density. Films with 21 vol% metal have dielectric constants of 50@1 Hz. Structural and electrical characterization using transmission electron microscopy, small-angle X-ray scattering, and impedance spectroscopy indicates that classical random capacitor-resistor network models partially describe this hybrid material but fail at high metal fractions, where the covalently attached shell prevents percolation and ensures high dielectric constants without the risk of dielectric breakdown. A comparison of disordered to ordered films indicates that the network structure affects dielectric properties less than the metal content. The applicability of the new dielectric material is demonstrated by formulating inkjet inks and printing devices. An inkjet-printed capacitor with an area of 0.79 mm2 and a 17 nm thick dielectric had a capacitance of 2.2±0.1 nF@1 kHz .

We discuss the complex interplay between host and guest dynamics for a polymer in soft confinement by a droplet-phase microemulsion. Intermediate scattering functions obtained by neutron spin echo spectroscopy are first analysed by means of an effective diffusion coefficient. From its dependence on the absolute of the scattering vector q we concluded a sophisticated model for the systems dynamics taking both polymer and microemulsion contributions into account. Global fitting of this model to the intermediate scattering functions at all measured q-values and all investigated confinement sizes eventually allows for a precise disentangling of the pure polymer dynamics in confinement from the overlaying microemulsion dynamics. Validity of our approach is further supported by numerical random walk calculations.

Ionic liquids are an attractive material class due to their wide liquid range, intrinsic ionic conductivity, and high chemical as well as electrochemical stability. However, the widespread use of ionic liquids is hindered by significantly higher viscosities compared to conventional molecular solvents. In this work, we show how the transport properties of ionic liquids can be altered significantly, even for isostructural ions that have the same backbone. To this end, structure–property relationships have been determined for a set of 16 systematically varied representative ionic liquids. Variations in molecular structure include ammonium vs. phosphonium, ether vs. alkyl side chains, and rigid vs. flexible anions. Ab initio calculations are used to relate molecular structures to the thermal, structural and transport properties of the ionic liquids. We find that the differences in properties of ether and alkyl functionalised ionic liquids are primarily dependent on minimum energy geometries, with the conformational flexibility of ether side chains appearing to be of secondary importance. We also show unprecedented correlations between anion conformational flexibility and transport properties. Critically, increasing fluidity upon consecutive introduction of ether side chains and phosphonium centres into the cation is found to be dependent on whether the anion is flexible or rigid. We demonstrate that targeted design of functional groups based on structure–property relationships can yield ionic liquids of exceptionally high fluidity.

Elastin-like peptides are biopolymers that display LCST behaviour in solution quite similar to other synthetic polymers like polyethylene oxide. Here we study the structure of the peptide GVG(VPGVG)3 in a temperature range of 25 °C to 70 °C with small angle neutron scattering. The LCST for this peptide is outside the experimental range of temperatures. Molecular conformation is well described within the model of a random coil but increasing temperature leads to significant changes. The peptide displays a combination of conformational change and aggregation that show up in the scattering at low and intermediate scattering vector q. The aggregate size is determined from an integral measure of the scattered intensity. It increases with temperature and concentration. For low concentration we find a size variation with temperature that may be related to the collapse of conformation at the inverse temperature transition (ITT).

Metallopolymers are a unique class of functional materials because of their redox-mediated optoelectronic and catalytic switching capabilities and, as recently shown, their outstanding structure formation and separation capabilities. Within the present study, (tri)block copolymers of poly(isoprene) (PI) and poly(ferrocenylmethyl methacrylate) having different block compositions and overall molar masses up to 328 kg mol–1 are synthesized by anionic polymerization. The composition and thermal properties of the metallopolymers are investigated by state-of-the-art polymer analytical methods comprising size exclusion chromatography, 1H NMR spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. As a focus of this work, excellent microphase separation of the synthesized (tri)block copolymers is proven by transmission electron microscopy, scanning electron microcopy, energy-dispersive X-ray spectroscopy, small-angle X-ray scattering measurements showing spherical, cylindrical, and lamell...

The journal of chemical physics 155(12), 124902 (2021). doi:10.1063/5.0058503, We examine network formation and percolation of carbon black by means of Monte Carlo simulations and experiments. In the simulation, we model carbon black by rigid aggregates of impenetrable spheres, which we obtain by diffusion-limited aggregation. To determine the input parameters for the simulation, we experimentally characterize the micro-structure and size distribution of carbon black aggregates. We then simulate suspensions of aggregates and determine the percolation threshold as a function of the aggregate size distribution. We observe a quasi-universal relation between the percolation threshold and a weighted average radius of gyration of the aggregate ensemble. Higher order moments of the size distribution do not have an effect on the percolation threshold. We conclude further that the concentration of large carbon black aggregates has a stronger influence on the percolation threshold than the concentration of small aggregates. In the experiment, we disperse the carbon black in a polymer matrix and measure the conductivity of the composite. We successfully test the hypotheses drawn from simulation by comparing composites prepared with the same type of carbon black before and after ball milling, i.e., on changing only the distribution of aggregate sizes in the composites., Published by American Institute of Physics, Melville, NY

Polyethylene glycol is water soluble and forms an eutectic system with water. The eutectic temperature is −19 °C for M=1500 g mol−1 and increases with molecular weight. The dielectric relaxation spectrum of the mixtures exhibits a strong loss maximum in ϵ″ (ω) similar to pure water. Relaxation time increases with the addition of PEG. Activation energies exhibit a maximum of 0.35 eV at molar fraction χp ≈0.2. This compares well with results on ethanol water mixtures. Adding PEG molecules to nanoscopic water droplets of inverse microemulsions has only small impact on the bending modulus κ of a non-ionic microemulsion. In AOT based microemulsions an increase or decrease of κ is found in dependence on the size of the droplets. This is in accordance with the variation of the dynamic percolation transition in the same systems.

The existence of magnetic dipolar nanoparticle chains at zero field has been predicted theoretically for decades, but these structures are rarely observed experimentally. A prerequisite is a permanent magnetic moment on the particles forming the chain. Here we report on the observation of magnetic dipolar chains of spherical iron oxide nanoparticles with a diameter of 12.8 nm. The nanoparticles are embedded in an ultrathin polymer film. Due to the high viscosity of the polymer matrix, the dominating aggregation mechanism is driven by dipolar interactions. Smaller iron oxide nanoparticles (8 nm) show no permanent magnetic moment and do not form chains but compact aggregates. Mixed monolayers of iron oxide nanoparticles and polymer at the air-water interface are characterized by Langmuir isotherms and in situ X-ray reflectometry (XRR). The combination of the particles with a polymer leads to a stable polymer nanocomposite film at the air-water interface. XRR experiments show that nanoparticles are immersed in a thin polymer matrix of 2 nm. Using atomic force microscopy (AFM) on Langmuir-Blodgett films, we measure the lateral distribution of particles in the film. An analysis of single structures within transferred films results in fractal dimensions that are in excellent agreement with 2D simulations.

Elastin-like peptides are biopolymers that display LCST behaviour in solution quite similar to other synthetic polymers like polyethylene oxide. Here we study the structure of the peptide GVG(VPGVG)3 in a temperature range of 25 °C to 70 °C with small angle neutron scattering. The LCST for this peptide is outside the experimental range of temperatures. Molecular conformation is well described within the model of a random coil but increasing temperature leads to significant changes. The peptide displays a combination of conformational change and aggregation that show up in the scattering at low and intermediate scattering vector q. The aggregate size is determined from an integral measure of the scattered intensity. It increases with temperature and concentration. For low concentration we find a size variation with temperature that may be related to the collapse of conformation at the inverse temperature transition (ITT).

Nanoporous ion track-etched polycarbonate is ideally suited for the study of confined polymers via small angle X-ray scattering (SAXS) due to the strictly parallel orientation of the pores as well as their uncorrelated lateral distribution. Nanopores with radii ranging from 17 to 213 nm are prepared and coated with SiO2via atomic layer deposition in order to obtain a well-defined and homogeneous surface. A low molecular weight polyethylene glycol (PEG) homopolymer with a semicrystalline lamellar bulk structure is introduced into the nanopores via melt infiltration. At high temperatures SAXS measurements confirm a uniform filling of the pores with amorphous polymer. Upon cooling below the melting point of PEG, a concentrical structure of semicrystalline lamellae is revealed for large pore radii. We introduce models which successfully describe the combined scattering from nanopores and semicrystalline or amorphous PEG inside. DSC measurements of the confined polymer show a decrease of melting temperature and heat of fusion per gram polymer upon reduction of the pore radius and hint at a change in the lamellar configuration.

We study the conformation of a polymer (polyethylene glycol) in a nanoscopic soft confinement with attractive walls. The polymer is added to a water-in-oil microemulsion based on the deuterated anionic surfactant AOT, d-octane and D2O. Three different droplet sizes and up to three polymers per droplet are investigated with small angle scattering combining X-rays and neutrons. This allows determining the confinement size and polymer conformation on identical samples. Whereas polymer conformation in bulk is found to be well described with the model of a Gaussian coil its radius of gyration is drastically increased in the droplet. At the same time it is compressed on a local scale. This supports the picture of a polymer strongly adsorbed on the surfactant layer with a thickness of several Angstroms.

Within this work, well-defined polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA) and a non-polar model block copolymer (BCP) polystyrene-block-polybutadiene (PS-b-PB) have been prepared via sequential anionic polymerization and investigated with respect to their capability of microphase separation in the presence of cellulose fibres. Both the original morphologies in the bulk state as well as the microphase-separated structures in the vicinity of cellulose fibres were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) measurements. BCP series featuring molar masses below 70 kg mol−1 and higher molar masses up to 201 kg mol−1 have been subjected to solvent-casting and subsequent thermal annealing to elucidate the microstructures in the presence or absence of cellulose fibres with defined contents of water. Besides the classical morphologies comprising spheres, cylinders and lamellae, also gyroidal and helical-domains were observed. Moreover, a significant impact on the degree of domain order and orientation was found for the PHEMA-containing BCPs based on the hydroxyl moiety interactions of the cellulose fibres and respective PHEMA block segments.

A one-pot approach for the preparation of diblock copolymers consisting of polystyrene and polymyrcene blocks is described via a temperature-induced block copolymer (BCP) formation strategy. A monomer mixture of styrene and myrcene is employed. The unreactive nature of myrcene in a polar solvent (tetrahydrofuran) at -78 °C enables the sole formation of active polystyrene macroinitiators, while an increase of the temperature (-38 °C to room temperature) leads to poly(styrene-block-myrcene) formation due to polymerization of myrcene. Well-defined BCPs featuring molar masses in the range of 44-117.2 kg mol-1 with dispersities, Ð, of 1.09-1.21, and polymyrcene volume fractions of 30-64% are accessible. Matrix assisted laser desorption ionization-time of flight mass spectrometry measurements reveal the temperature-controlled polymyrcene block formation, while both transmission electron microscopy and small-angle X-ray scattering measurements prove the presence of clearly microphase-separated, long range-ordered domains in the block copolymers. The temperature-controlled one-pot anionic block copolymerization approach may be general for other terpene-diene monomers.

Aqueous redox flow batteries using electroactive organic materials are currently attracting significant attention. However, the influence of supporting electrolytes on the aqueous solubility, electrochemical reversibility and chemical stability of the organic components has rarely been investigated. Here, a new electrolyte design strategy towards enhanced solubility and chemical stability of active materials is proposed by using interaction-mediating species. 3 molality aqueous imidazolium chlorides, with high ionic conductivity and water-like flowability, enable a record aqueous solubility of 4.3 M for a commercially available nitroxyl radical and reversible 2e− reaction of unmodified methyl viologen at moderate concentrations. With 0.6 M electrolyte, flow cell shows remarkable chemical stability of the nitroxyl radical, excellent cycling stability over 250 cycles at 80 mA cm−2, and a peak power density of 121.6 mW cm−2 at 175 mA cm−2. Furthermore, nitroxyl radical catholyte with a concentration of 3 M is tested in a flow cell. It maintains an impressive steady energy efficiency of 65% at 30 mA cm−2. This work paves a new way for the development of high performance aqueous electrolytes based on organic materials.

The bending modulus κ is known to be a crucial parameter for the stability of the droplet phase in microemulsion systems. For AOT based water in oil microemulsions the bending modulus of the surfactant has values close to kBT but can be influenced by the presence of polymers. In this work we focus on the water soluble polymer polyethylene glycol and how it influences the bending modulus. An increase by a factor of three is found. For the correct evaluation of the bending modulus via percolation temperatures and droplet radii, thus by dielectric spectroscopy and small angle X-ray scattering, the determination of the radii right at the percolation temperature is crucial as we will show, although it is often neglected. In order to precisely determine the droplet radii we will present a global fitting model which provides reliable results with a minimum number of free fitting parameters.

We study the dielectric relaxation in paper of different density and in microcrystalline cellulose in a temperature range between 150 K and 350 K. Qualitatively the spectra display the same relaxations α, β, γ. An additional relaxation, βwet, is found in humidified samples. The adsorption of water is determined and related to the humidity of the surrounding. Two adsorption processes are identified as primary and secondary adsorption at the hydroxyl groups in the amorphous domains of the cellulose. The γ process in the dielectric spectrum is found to be directly related to the amount of water adsorbed in the sample. While qualitatively the differences to unprocessed, microcrystalline cellulose are negligible, quantitatively the less localised β-relaxation shows an increased relaxation strength induced by the geometrical confinement and orientation effects due to the processing into cellulose fibres. While the manufacturing process leads to paper with different density and porosity there is no significant change in water uptake, structure or dynamics.

High aspect-ratio nanochannels were fabricated by irradiating polyimide films with swift heavy ions of 2.2 GeV energy and subsequently sensitising and etching the ion tracks in hydrogen peroxide and sodium hypochloride, respectively. The nanochannels were analysed by means of small angle X-ray scattering in combination with a new form factor model that considers bi-conical channel geometry. This approach allows us to tune the etching parameters for controlled channel shape adjustment.

The crystallization and melting behavior of a series of poly(1,1-dimethysilacyclobutane) (PDMSB) samples accessible via living anionic polymerization protocols with different molar masses were studied by differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS) and X-ray diffraction (XRD). It has been found that in the cooling process only one crystallization exotherm was observed by using DSC, but in subsequent heating two clear endotherms appeared. DSC measurements additionally revealed that there will be two melting peaks when the isothermal crystallization temperature, Tc, is low enough, but only one melting peak could be obtained when Tc is high. The value of the lower melting peak Tm1 increased with Tc, showing the increase of lamella thickness due to increase of Tc, which was also evidenced by using SAXS measurements. However, the value of the higher melting peak Tm2 stayed almost constant with Tc. XRD analysis showed that there is only one crystal form independent of Tc. While SAXS results revealed only one long range order, indicating this multiple endotherms phenomenon was caused by the recrystallization process during heating, but not isothermal thickening and thinning process as observed for e.g. poly(ethylene oxide)s (PEOs) with low molar masses. Heating rate dependent DSC experiments showed that there are two recrystallization processes with different time scales. The recrystallization at low temperature always showed up independent of heating rate while the recrystallization at high temperature showed up only when the heating rate was very low. This interesting phenomenon was explained by the different energy barrier for the recrystallization process at low and high temperature as shown by in situ SAXS measurements during heating.

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.I. INTRODUCTION

This contribution deals with a special class of soft matter systems called microemulsions. They are mixtures of oil and water stabilized with a surfactant. The stabilisation is achieved through the reduction of interfacial tension by the amphiphilic surfactant. They thus consist of oil and water phases separated by a surfactant layer. The nanoscopic structure of these phases, in particular that of spherical nano droplets, is analysed in this chapter. The impact of temperature and mixing ratio of the constituents is shown. The fascinating phenomenon of dynamic droplet percolation and aggregation near a temperature induced phase separation are discussed. Microemulsions provide an excellent model system for the investigation of confinement effects on molecules. Conversely these guest molecules modify structural and dynamical properties of the microemulsion. This may even lead to the formation of transient networks with short time gel-like and long time self-diffusion dynamics of droplets.

We investigate the structure and shell dynamics of the droplet phase in water/AOT/octane microemulsions with polyethyleneglycol (MW = 1500) molecules loaded in the droplets. Size and polydispersity of the droplets is determined with small angle X-ray scattering and small angle neutron scattering experiments. Shell fluctuations are measured with neutron spin echo spectroscopy and related to the dynamic percolation seen in dielectric spectroscopy. Shell fluctuations are found to be well described by the bending modulus of the shell and the viscosities inside and outside the droplets. Addition of the polymer decreases the modulus for small droplets. For large droplets the opposite is found as percolation temperature shifts to higher values.

Water dependent secondary relaxations are well known in glass formers. In Poly(ɛ-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.