Aqueous gels of triblock copolymers of ethylene oxide and 1,2-butylene oxide (type BEB) studied by rheometry

A triblock copolymer of ethylene oxide and 1,2-butylene oxide with hydrophilic central block and hydrophobic end blocks, denoted B10E227B10, was prepared and characterised. The frequency dependence of dynamic modulus was determined for micellar solutions in the concentration range of 8-20 wt.-% and the temperature range of 5-70 degrees C, and the fluid/gel diagram was established. The results were combined with those reported previously for copolymers B12E227B12 and B12E114B12 to obtain insight into the effect of B-block and E-block length on the rheological properties of systems of this type. The results are discussed in terms of micelles forming bridged networks and, at higher concentrations, packing in structured gels.