Aggregate morphology and flow behaviour of micellar alkylglycoside solutions

Solutions of n-nonyl-beta-D-glucoside (C(9)G(1)), n-decyl-beta-D-glucoside (C(10)G(1)), n-dodecyl-beta-D-maltoside (C(12)G(2)) n-tetradecyl-beta-D-maltoside (C(14)G(2)) and C(9)G(1)/C(10)G(1) mixtures have been characterised by capillary viscometry and rheology in H2O and D2O, in order to map the influence of surfactant characteristics on micellisation over a wide concentration range. For the maltosides, the micellar solutions are shear thinning with a zero-shear viscosity that scales with concentration according to a power law with an exponent of about 5.8. In contrast, solutions of the glucosides C(9)G(1), C(10)G(1) and their mixtures show Newtonian flow behaviour and a much lower scaling exponent (< 2.4). In C(9)G(1)/C(10)G(1) mixtures, the scaling exponent decreases monotonously with increasing C(10)G(1) content. The flow behaviour correlates with the packing requirements of the various surfactants, and are compatible with the idea that the maltosides form worm-like micelles, whereas the glucosides form branched, interconnected micelles (C(9)G(1)) and space-filling micellar networks (C(10)G(1)).