Poly (amidoamine) dendrimer interactions with sodium dodecyl sulfate studied by viscosity measurements

The relative viscosity (ηr) measurements of poly (amidoamine) (PAMAM) dendrimers + sodium dodecyl sulfate (SDS) + water systems were carried out at 25 °C with the help of capillary viscometer by changing the concentrations of SDS and PAMAM, and by changing the number of generations from 0G to 1G of PAMAM. The ηr plots of SDS in aqueous PAMAM show clear aggregation process in the case of 0G and 0.5G. Evaluation of intrinsic viscosity demonstrates that it is much higher both for SDS ([η]SDS) as well as for PAMAM ([η]PAMAM) in the case of 0.5G rather than 0G and 1G. It indicates a stronger electrostriction effects operating between SDS and 0.5G PAMAM. This has been attributed to the favorable adsorption of Na+ counterions on the ester terminated surface groups of 0.5G, thus generating electropositive character.