Flexible Sample Environments for the Investigation of Soft Matter at the European Spallation Source: Part III—The Macroscopic Foam Cell

Abstract

The European Spallation Source (ESS), which is under construction in Lund (Sweden), will be the leading and most brilliant neutron source and aims at starting user operation at the end of 2023. Among others, two small angle neutron scattering (SANS) machines will be operated. Due to the high brilliance of the source, it is important to minimize the downtime of the instruments. For this, a collaboration between three German universities and the ESS was initialized to develop and construct a unified sample environment (SE) system. The main focus was set on the use of a robust carrier system for the different SEs, which allows setting up experiments and first prealignment outside the SANS instruments. This article covers the development and construction of a SE for SANS experiments with foams, which allows measuring foams at different drainage states and the control of the rate of foam formation, temperature, and measurement position. The functionality under ESS conditions was tested and neutron test measurement were carried out.

Structure formation of PNIPAM microgels in foams and foam films

“…Technical details are given in a previous publication. 54 Foams were produced from microgel dispersions in D 2 O ( w = 0.3, 0.5 and 1.0 wt%) by bubbling nitrogen gas at a rate of 10 mL min −1 through a porous glass plate (pore size 10–16 μm, porosity P16 (ISO 4793)) at the bottom of the cell. Once the foam level reached the top of the column the flow rate was reduced to a value to obtain a constant foam height over time and to prevent overflowing of the foam column.…”

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

“…A custombuilt sample cell, specifically designed for studying macroscopic foams with SANS, was used. Technical details are given in a previous publication (Ku ¨hnhammer et al, 2021). Foams were produced from a C 14 TAB solution in D 2 O (c = 3.5 mM) by bubbling nitrogen gas at a rate of 10 ml min À1 through a porous glass plate [pore size 10-16 mm, porosity P16 (ISO 4793)] at the bottom of the cell.…”

Technical Specification of the Small-Angle Neutron Scattering Instrument SKADI at the European Spallation Source

“…A kinematic mounting system will be installed in order to allow for an effective and speedy setup of the different experiments to be performed at SKADI. This kinematic mounting system will allow an off-instrument preparation of the experimental setup and several user groups have already developed corresponding sample environments [4][5][6]. This setup is designed to take up a load of up to 990 kg on the area of a EUR-pallet.…”

“…In addition, further practical requirements for performing experiments, such as sample area and environment, will be considered. Here, we want to highlight the extensive collaboration with user groups in order to develop state-of-the art sample environments [4][5][6].…”