Solvation dynamics of 4-aminophthalimide in a polymer (PVP)-surfactant (SDS) aggregate

Abstract

Solvation dynamics of 4-aminophthalimide (4-AP) in a polymer-surfactant aggregate comprising poly(vinylpyrrolidone) (PVP) and sodium dodecyl sulfate (SDS) is reported. In an aqueous solution even at a polymer concentration much higher than the cross over value (C^∗), a significant portion (30%) of 4-AP molecules do not bind to PVP. In the presence of a surfactant, SDS, 4-AP binds to the PVP-SDS aggregate completely at a polymer concentration greater than C^∗. The critical aggregation concentration (c.a.c.) of SDS for PVP is found to be 2 mM. The solvation dynamics of 4-AP in a PVP-SDS aggregate is observed to be slower compared to that in bulk water or in SDS micelles. The slow solvation dynamics is attributed to restrictions imposed on the water molecules squeezed between the polymer chain and micellar aggregates.