To study flow properties, use has been made of a new Anton-Paar Physica MCR501 rheometer at ISIS for simultaneous small angle neutron scattering (SANS) and rheometry measurements on the Loq instrument. The rheometer is a controlled stress / strain instrument with a custom built quartz Couette geometry (in which a fluid can be sheared between two concentric cylinders). Parallel studies with an identical instrument using cone-and-plate geometry have also been performed at Diamond I22.
It has been found that using mixtures of Pluronic block copolymers, commercial poly(ethylene oxide)-poly(propylene oxide) surfactants, the phase behaviour and hence the rheological properties (such as the gel stiffness and deformation under shear) can be manipulated, opening up potential new applications.
Future work will focus on other soft materials including peptide fibrils.
GE Newby, IW Hamley (University of Reading), SM King (ISIS)