Formation of organized adsorption layers by amphiphilic dendrimers

Abstract

The formation of organized adsorption films by amphiphilic AB-type surface-block dendrimers (generation G=3,4) with hydroxyl group/ n-hexyl group terminals on solid substrates has been investigated by atomic force microscopy, contact angle, and surface plasmon resonance. Then the surface characteristics have been compared with those of symmetric poly(amido amine) dendrimer (PAMAM). While the adsorption film of PAMAM is rather flat, surface-block dendrimers form bilayers and their accumulation because of their amphiphilic character. Dendrimers in bilayer, which is formed by pairing between hydrophobic blocks, take ‘pancake’ structure. Adsorption film surface has hydrophilic character, suggesting the hydrophilic OH terminal block faced to the solution. The amount of adsorption is more for the third-generation dendrimer than for the fourth-generation dendrimer, and the adsorption proceeds more for surface-block dendrimers than for PAMAM in relation to the hydrophobicity of dendrimers.