Capturing change in microstructure of physically assembled gels as a function of temperature and strain using in-situ RheoSAXS technique

The mechanical properties of physically assembled gels depend on their microstructure. During large deformation, gel microstructure changes leading to a change in their mechanical properties. Here, we have considered two gels that consist of 10% and 20%(w/w) of poly(styrene)-poly(isoprene)-poly(styrene) [PS-PI-PS] in mineral oil, a midblock selective solvent. At room temperature, collapsed PS-blocks form aggregates, which are bridged by the PI-chains resulting in a three-dimensional gel. We capture the microstructural transformation as a function of temperature in a RheoSAXS setup. The scattering data capturing the change in gel microstructure subjected to oscillatory shear-strain was collected in the 1-2 plane. Strain amplitude values of 10, 100, and 300% were applied on the gels, therefore we have been able to collect data both at small and large strain amplitude. At high strain amplitude, an elliptical two-dimensional scattering pattern has been observed indicating structural orientation along the applied strain direction. To quantify such orientation, we have estimated the anisotropic factor as a function of strain from these patterns.