ESR and NMR studies of poly (amidoamine) dendrimers with ionic surfactants in different media
The electron paramagnetic resonance (EPR) study has been carried out for the micellar solutions of various ionic surfactant solutions as well as various generations of aqueous dendrimer both in their respective presence as well as their absence at 25°C and in different media. From these measurements, the rotation correlation time (τB) have been calculated for all the ionic surfactant + PAMAM + water system. A variation in the τBvalue remains mostly constant for the dodecyltrimethyammonium bromide (DTAB) and tetradecyltrimethylammonium bromide (TTAB) + PAMAM + water ternary mixtures. The τBvalue shows an increase with the increase in the amount of PAMAM for SDS in basic medium and for 12-2-12 in acidic medium. It has been concluded from these results that SDS undergo complexation with all generations of PAMAM in basic medium and 12-2-12 in acidic medium and produce stronger hydrophobic environment. The nuclear magnetic resonance study (NMR) allowed us to evaluate the spin-spin relaxation (T1) times of SDS in the presence of all generations of PAMAM. The T1 values for all the tail protons of SDS showed a slight decrease with the increase in the constant amount of PAMAM suggesting the adsorption of PAMAM molecules on the micelle surface.