The most widely studied and commercially important block copolymers are poly(ethylene oxide) and poly(propylene oxide) triblocks. Known commercially as Pluronics, these copolymers are exploited for their gelling properties and are used widely in cosmetics, pharmaceuticals and industrial processes.
The ability to control the flow properties of these Pluronic block copolymers is important during processing and end-use. Using mixtures of Pluronic block copolymers is one method of manipulating structural and rheological properties such as gel stiffness and deformation under shear.
A new Anton-Paar Physica MCR501 rheometer at ISIS enabled scientists from the University of Reading to simultaneously measure both rheometry and small angle neutron scattering [Newby et al., J. Coll. Int. Sci. (2008) 329 54].
Pluronic block copolymers form micelles at the beginning of the gelling process. Once a sufficiently high micelle concentration is reached, lyotrophic liquid crystal phases are formed.
By using multiple techniques including small angle neutron scattering at ISIS and dynamic light scattering at the nearby Diamond Light Source the group determined how the formation of micelles and the packing density of the Pluronic block copolymer chains affects the gel phase diagram.
The results of the study give clear routes to modify the structure of Pluronic block copolymers and engineer their rheological properties for use in bio-medical product applications.