A More Informative Approach for Characterization of Polymer Monolithic Phases: Small Angle Neutron Scattering/Ultrasmall Angle Neutron Scattering

Abstract

Neutron scattering techniques have been used frequently to characterize geological specimens and to determine the structures of glasses and of polymers as solutions, suspensions, or melts. Little work has been reported on their application in determining polymers' structural properties relevant to separations. Here, we present a comparison of characterization results from nitrogen porosimetry and from combined small angle neutron scattering (SANS) and ultrasmall angle neutron scattering (USANS) experiments. We show that SANS is extremely sensitive to the pore characteristics. Both approaches can provide information about porosity and pore characteristics, but the neutron scattering techniques provide additional information in the form of the surface characteristics of the pores and their length scales. Fits of the scattering data show that cylindrical pores are present with diameters down to 0.6 μm and that, for length scales down to approxmately 20 Å, the material shows self-similar (fractal) slopes of -3.4 to -3.6. Comparison of these characteristics with other examples from the scattering literature indicate that further investigation of their meaning for chromatographic media is required.

Practical applications of small-angle neutron scattering

“…133 Additionally, the importance of evidence from microscopy techniques cannot be ignored as this provides critical information that can be fed into the SANS data modelling to increase accuracy. 78,79,[81][82][83][84][100][101][102]112,114,115,120,125 In the condensed phase, the combination of multiple techniques can be used to build up detailed pictures, such as those established for P3HT gels and films. [84][85][86][92][93][94][95] The ability to generate such detail is clearly of benefit to the identification of structureproperty relationships and SANS has a crucial role to play, particularly in determining the statistically significant structural parameters.…”

“…Throughout the described examples, high importance is placed on the application of SANS alongside other scattering techniques. This can be used to increase the range of sizes detected, using USANS, 11,12,84,115 or to provide a different contrast, using SAXS, 44,45,55,56,114,118 from which material composition can additionally be estimated using ACV. 133 Additionally, the importance of evidence from microscopy techniques cannot be ignored as this provides critical information that can be fed into the SANS data modelling to increase accuracy.…”

“…For samples containing a large single pore size or multiple pore-size distributions, USANS is often used. [114][115][116][117] Additionally, measurements combining SAXS and SANS, 114,118 or using contrast variation SANS, with either 1 H-or 2 D-toluene contained within the pores, 119 can be used to gain more information and highlight particular regions within a structure. SANS has also recently been employed alongside a variety of other techniques (cf.…”

Structural Characterization of Porous Materials Using SAS

“…Benefits offered by USANS and SANS in this area have not yet been fully appreciated by the community. So far, we are aware of only one paper in which USANS and SANS were employed to study the structure of polymer monoliths in combination with TEM and gas adsorption methods [72].…”

Functional monolithic platforms: Chromatographic tools for antibody purification

“…The introduction of other recent techniques, such as scanning coupled contactless conductivity (sC4D) methods, confocal laser scanning microscopy, magnetic resonance imaging and small angle neutron scattering, offers innovative options to complement the aforementioned techniques in order to attain a thorough understanding of monolith structural features [81–83].…”