Self-assembly modulation in ionic PAMAM derivatives

Abstract

The self-assembly behaviour both in the bulk and water of a series of amphiphilic dendrimers constituted by second generation PAMAM ionically functionalized with different amounts of myristic acid is shown here. The number of acids in the dendrimer determines the liquid-crystal properties and the structural parameters of their supramolecular organization. Most of them present mesomorphism, organizing in a smectic A mesophase, with a layer spacing decreasing when increasing the number of acids. All these dendrimers form well-defined nanoobjects in water. Micelles and broken lamellae have been found for compounds with low acid contents. In contrast, dendrimers with higher fatty acid contents self-assemble forming nanospheres with a lamellar nanostructure. All compounds are able to trap the hydrophobic molecule 9,10-diphenylanthracene independent of the acid contents. Interestingly, the trapped hydrophobic molecule dominates the self-assembly trend of the dendrimers with low acid contents and thus different nanoobjects are found after the encapsulation.