Neutron small angle scattering

Using the many options offered by H/D contrast variations in polymer systems or other soft matter samples, SANS (Small Angle Neutron Scattering) enables scientists to gain a detailed insight into molecular conformation and the sociated behaviour of molecular components. The small angle scattering instruments KWS-1, KWS-2 and KWS-3 at FRMII in Garching make it possible to analyse structures on a scale ranging between 1nm and 1000nm. Where possible, accompanying images can also be produced if necessary using transmission electron microscopy (TEM).

Neutron small angle scattering (SANS) as a technique is also an exceptionally important tool to study material in an external field, when combined with macroscopic characterization techniques, such as rheology, for instance. Within the framework of our research activities, we analyse the structural response of polymers on a shear and extension deformation in space and time as well as in in-situ experiments.

Branched polymers behave differently from linear chains. Time-dependent phenomena taking place at different length scales can now be decoupled and studied in static experiments, by freezing each respective state. Quenched melts from partially labelled branched co-polymers can thus be studied using the in-situ SANS method and coupled extensional rheology, to investigate structural relaxation on different hierarchical levels. The topological tube is here closely related to the relaxation of stress.

The temporal development of structural changes, aggregations or phase transitions, ranging from a few seconds up to a number of hours, can be used in kinetic SANS measurements, e.g. by using so-called “stopped-flow” techniques.