Soft Matter

Zoom Science

The soft matter themes relevant to SANS2d will be extended to longer length scales by ZOOM, for example in areas such as colloidal particles, emulsions, foams, lamellar fragments, block copolymers, and their interactions with each other and other macro-molecules or particles. ZOOM is ideal for oriented systems, where anisotropic scatter covers a wide range of length scales, such as those obtained under shear, laminar and extensional flow or within complex geometries. Micron and sub-micron particles and droplets occur in a wide range of systems, often in conjunction with smaller micelles or polymers. In this area the larger samples required for use with lenses should not be an issue. Mechanisms of polymer reorganisation and crystallisation may be studied in detail in conjunction with SAXS by using contrast variation. “Pre-order phases” in crystallisation kinetics are expected to be larger than the final 100 to 500 Å d-spacings. Large scale elastic inhomogeneities in strained polymers, revealed by deuterium labelling, are currently not well understood. Responsive polymers in micro-gel networks can change structure dramatically and reversibly with temperature, pH or chemical stimulus making them ideal for encapsulation and controlled release situations. The wide Q range of ZOOM down to smaller Q’s would greatly improve understanding of such systems. Development of focussed beams to enhance count rates from small sample volumes in areas such as flow fields, injection moulding, extrusion processing or perhaps even “microfluidic” confinement would be an exciting prospect, even with sample channels of ~ 1mm size. Major research programmes are currently under way to study the rheology, deformation and relaxation of polymers during processing. Small focus beams would desirably improve count rates from the often small sample volumes. As the degree of control over polymer architecture by advanced synthesis methods improves and industrial polymers continue to become more sophisticated, this area of study will continue to expand. Deuterium labelling is often the only way to study structure in polymer melts, thus ZOOM would extend the use of neutrons in this field. In extensional flow LOQ has already been used with 2 mm diameter beam to study the orientational distributions of flowing strongly scattering surfactant lamellar phases, many other samples would scatter much more weakly and would benefit from a sample focussed beam.

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