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We show the implementation of superconducting magnetic Wollaston prisms for spin echo small-angle neutron scattering. Two calibration methods for the spin echo length are presented: one utilizing spin echo modulated small-angle neutron scattering and the other based on the neutron refraction by quartz wedge crystals. Our experimental results with polystyrene nano-particle colloids showcase the system's efficacy in measuring both dilute and concentrated colloidal systems. Additionally, investigations into the pore diameter and pitch of a nano-porous alumina membrane demonstrate its capability in analyzing nano-porous materials. Furthermore, we discuss potential optimizations to further extend the accessible spin echo length. [ABSTRACT FROM AUTHOR]

The microstructure of wormlike micelles (WLM) directly affects the rheological properties of their solutions. Investigating the structure–property relationships of WLM has long been a popular topic for researchers who have developed theoretical and empirical models to describe their viscoelastic behavior. All these models rely on a collection of characteristic "length" parameters that are often difficult to estimate using relatively simple rheological tests. In particular, the micelle stiffness, as described by the persistence length, can be difficult to measure experimentally, while being very impactful on the bulk rheology of WLM solutions. Here, an array of inorganic salts (NaCl, LiCl, MgCl2, NaBr, NaI, and Na2SO4) have been used to induce wormlike micelle formation in an aqueous solution of the surfactant sodium lauryl ether sulfate. Ion dissociation/association with the surfactant head groups and the hydrogen bond network of the water alters the effective stiffness of the micelles, allowing for an estimation of the stiffness using three different methods: (1) small angle neutron scattering (SANS) measurements, (2) oscillatory rheological measurements, and (3) steady rheological measurements with a thermodynamic packing parameter model. Each of these methods are then compared and shown to be consistent with each other for the micelle solutions tested. The consistency of the results across all the measurements suggests that the approach used in this study, which estimates micelle parameters using steady shear rheology and a thermodynamic model, could provide a simpler and more accessible method for estimating micelle parameters in a wide range of surfactant systems. [ABSTRACT FROM AUTHOR]

An electrically percolated network structure of conjugatedpolymers is critical to the development of organic electronics. Herein,we investigate the potential to rationally design an interconnectednetwork of conjugated polymers using the gelation of poly(3-hexylthiophene)(P3HT) as a model system. The three-dimensional network structureis evaluated through small-angle neutron scattering (SANS) and ultrasmall-angleneutron scattering (USANS). The analytical models used for data fittingprovide relevant structural parameters over multiple length scales.Structural parameters include the fiber cross section (height andwidth), the specific surface area, and the network density (i.e.,fractal dimension). Simultaneous rheological and conductivity measurementsalso provide insight into the development of the mechanical and electricalproperties of organogels and allow us to propose a detailed gelationmechanism for P3HT. The fiber shape is found to be relatively independentof the solvent type, but P3HT organogels show distinct differencesin conductivity, which can be directly linked to differences in thebranching network structures. These results suggest that the gelationof fiber-forming conjugated polymers offers an excellent platformfor designing electrically percolated networks that can be used forstructural optimization in organic electronic devices. [ABSTRACT FROM AUTHOR]