Aqueous Gels of Triblock Copolymers of Ethylene Oxide and 1,2‐Butylene Oxide (Type BEB) Studied by Rheometry

Summary: 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 °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.

Temperature dependence of the logarithm of storage modulus for aqueous solutions of copolymer B₁₀E₂₂₇B₁₀ at the concentrations (wt.‐%) indicated. Conditions: f = 1 Hz, A ≈ 0.5%.