The largest effect would be on how the spacer affects the phase behaviour of the surfactant. Micellar is virtually only viscous, hexagonal, would be strongly viscoelastic, cubic (in all its various forms) would be even more (have higher )viscoelasticity, then lamellar would have reduced moduli, and so be less viscoelastic

paul

Nilanjan Pal

The shorter the spacer, the lower the mobility of hydrophilic fragments and the higher the tendency of surfactant molecules to aggregate. The longer the spacer, the lower the surfactant ability to aggregate. The lower the ability of the surfactant to aggregate, the larger the CMC and the size of micelles and the higher the viscosity of the solution.