Hydrophobically Modified Gelatin and Its Interaction in Aqueous Solution with Sodium Dodecyl Sulfate

Abstract

The interaction between a series of hydrophobically modified gelatins and the anionic surfactant sodium dodecyl sulfate SDS in a pH = 6.6/34 mM buffer has been investigated by surface tension, pulsed-gradient spin−echo NMR, viscosity, and small-angle neutron scattering. In the absence of the surfactant, the bulk viscosity of all the gelatins examined here is dependent only on the gelatin concentration and is independent of the number and size of any grafted hydrophobe. Similarly, the small-angle neutron scattering for all samples could be well-described by a two length-scale model. In this model, the smaller dimension represents the local structure of the gelatin molecule and is unaffected by the presence of the hydrophobe(s), while a larger dimension characterizing the network structure increases significantly with the presence of the hydrophobe but not their size. On addition of the anionic surfactant sodium dodecyl sulfate (SDS), the interaction between surfactant and the hydrophobic gelatin with low g...