Studying nonlinear viscoelastic properties of soft condensed matter with time-of-flight based RheoSANS measurements

Soft condensed matter is of great interest for fundamental science as well as with respect to applications in medical engineering, for example as lubrication or as responsive biomaterials, to name just a few. This is enabled by the tuneability of viscoelastic properties of polymeric materials. We are interested in the linear triblock copolymer Pluronic F127, which self-assembles into micelles at specific temperatures and mass concentration when diluted in water. Of particular interest is it to identify and characterize non-linearities in stress-strain relationship of the materials. We aim to investigate this domain by using the available rheometer at ISIS to apply Large Amplitude Oscillatory Shear (LAOS) to our sample. One cycle of shear application will be in the range of 1 Hz, which is an interesting time scale to investigate crystallization processes and subsequently non-linear effects like shear bands, which we propose to investigate with an experiment at SANS2D. Neutron data will be taken in event mode, which enables us to link every detected neutron to the stress-strain curve of the rheometer by a time-of-flight measurement. This method makes later analysis and potential rebinning of the data possible. Our proposal suggests to make measurements at different shear amplitudes and frequencies as well in radial and tangential orientation and for several points in the sample to obtain a spatial resolution. Overall, we ask for 4 days of beam time at SANS2D.