Repulsive, but sticky - Insights into the non-ionic foam stabilization mechanism by superchaotropic nano-ions.

Hypothesis: The superchaotropic Keggin polyoxometalate α-SiWO (SiW) was recently shown to stabilize non-ionic surfactant (CE) foams owing to electrostatic repulsion that arises from the adsorption of SiW-ions to the foam interfaces. The precise mechanism of foam stabilization by SiW however remained unsolved.

Experiments: Imaging and conductimetry were used on macroscopic foams to monitor the foam collapse under free drainage and small angle neutron scattering (SANS) at a given foam height allowed for the tracking of the evolution of film thickness under quasi-stationary conditions.

When Bulk Matters: Disentanglement of the Role of Polyelectrolyte/Surfactant Complexes at Surfaces and in the Bulk of Foam Films.

Foam films display exciting systems as on one hand they dictate the performance of macroscopic foams and on the other hand they allow studies of surface forces. With regard to surface forces, we attempt to disentangle the effect of the foam film surfaces and the foam film bulk. For that, we study the influence of salt (LiBr) on foam films formed by mixtures of oppositely charged polyelectrolyte and surfactant: anionic monosulfonated polyphenylene sulfone (sPSO-220) and cationic tetradecyltrimethylammonium bromide (CTAB).

A new model to describe small-angle neutron scattering from foams.

The modelling of scattering data from foams is very challenging due to the complex structure of foams and is therefore often reduced to the fitting of single peak positions or feature mimicking. This article presents a more elaborate model to describe the small-angle neutron scattering (SANS) data from foams. The model takes into account the geometry of the foam bubbles and is based on an incoherent superposition of the reflectivity curves arising from the foam films and the small-angle scattering (SAS) contribution from the plateau borders.

Insights into Extended Structures and Their Driving Force: Influence of Salt on Polyelectrolyte/Surfactant Mixtures at the Air/Water Interface.

This paper addresses the effect of polyelectrolyte stiffness on the surface structure of polyelectrolyte (P)/surfactant (S) mixtures. Therefore, two different anionic Ps with different intrinsic persistence length are studied while varying the salt concentration (0-10 M). Either monosulfonated polyphenylene sulfone (sPSO-220, ∼20 nm) or sodium poly(styrenesulfonate) (PSS, ∼1 nm) is mixed with the cationic surfactant tetradecyltrimethylammonium bromide (CTAB) well below its critical micelle concentration and studied with tensiometry and neutron reflectivity experiments.

Gold nanoparticle distribution in polyelectrolyte brushes loaded at different pH conditions.

Composites made of polymer brushes with inclusions of gold nanoparticles (AuNPs) combine the responsive nature of polymer brushes with the optical properties of the AuNPs, which offers the possibility to be used as colorimetric sensors. To this end, it is crucial to know how AuNPs are distributed inside the brush. Here, this distribution was elucidated by neutron reflectometry with contrast variation and a self-consistent reflectivity analysis based on the analytical parameterization of the volume fraction profiles of all chemical components.

Introduction of Non-Vitamin K Antagonist Anticoagulants Strongly Increased the Rate of Anticoagulation in Hospitalized Geriatric Patients with Atrial Fibrillation.

Background: The benefit of anticoagulative treatment to prevent thromboembolism has been established in patients with atrial fibrillation and flutter of all age groups. Traditionally, anticoagulation was underused in geriatric patients with atrial fibrillation and flutter.

Objective: The aim of this study was to assess whether the broad introduction of non-vitamin K antagonist oral anticoagulants into clinical medicine has changed the rate of older patients treated with anticoagulants for atrial fibrillation and flutter.

Polymers and surfactants at fluid interfaces studied with specular neutron reflectometry.

This review addresses the advances made with specular neutron reflectometry in studies of aqueous mixtures of polymers and surfactants at fluid interfaces during the last decade (or so). The increase in neutron flux due to improvements in instrumentation has led to routine measurements at the air/water interface that are faster and involve samples with lower isotopic contrast than in previous experiments. One can now resolve the surface excess of a single deuterated component on the second time scale and the composition of a mixture on the minute time scale, and information about adsorption processes and dynamic rheology can also be accessed.