Aqueous Gels of Diblock Oxyethylene-Oxypropylene Copolymers

Abstract

Aqueous solutions of diblock copolymers E102P37 and E92P55 (E = oxyethylene unit, P = oxypropylene unit) were investigated by rheometry. Storage (G′) and loss (G″) modulus and yield stress (σy) were used to detect and characterise hard and soft gels in experiments which covered the concentration range 4–28 wt.-% copolymer and the temperature range 5–85 °C. Comparison is made with phase diagrams reported for other diblock copoly(oxyalkylene)s, and it is shown that the mesophase behaviour of these systems depends on the effective thickness of the E-block corona and the stability of the micelles at low temperatures.