Liquid Crystal Phase Behavior of Branched Poly(oxyethylene) Surfactants

The phase behavior of several novel surfactants having hydrophobic and poly(oxyethylene) (EOm) polar groups linked by a glyceryl (G) moiety has been studied using the optical microscope penetration scan. Use of the G linker gives surfactants with two EO groups attached to one hydrophobic chain, or two hydrophobic chains attached to one EO group, so that both the hydrophobic and polar groups can be considered to be “branched”. Several surfactants having the general formula X−O−CH2−CH(OY)−CH2−O−X, where X = alkyl chain and Y = EOm or vice versa, have been examined, mostly with oleyl chains (C18) as the hydrophobic group(s). In addition, we also examined two conventional surfactants with oleyl hydrophobic groups to allow a proper comparison of the novel surfactants with the available literature. Generally, we find that the mesophases observed are similar to those found for conventional surfactants, with the “packing constraint” model providing a reasonable qualitative description of behavior. Also, the data ...