Effects of Additives on the Phase Behavior of an EO/PO-Copolymer

Certain EO/PO-triblock polymers can form densely packed spherical micelles and cubic liquid crystalline phases at high concentrations.

Usually these are highly elastic and inherently stable gels. This article deals with the effect of various additives on the phase behavior of an EO/PO-triblock polymer, in particular on the existence range of the cubic phase. The effects were characterized by means of rheology, zeta potential measurement, DOSY, and SAXS. It was found that some additives e.g. ionic surfactants decreased the existence range of the cubic phase, whereas others e.g. saccharides showed the reverse effect. The predominant mechanisms for these opposite effects might be different for various additives. However, certain regularities were identified probably due to three different interfering mechanisms. One mechanism is related to additives which can change the polymer-water interface, e.g. n-butanol. Other additives might change the hydration shell of the EOPO-polymers, e.g. maltose. Furthermore, complexation processes could occur, e.g. in case of surfactants, which decrease the