Radially layered copoly (amidoamine-organosilicon) dendrimers

Radially layered copoly-dendrimers having unusual surface properties and novel applications have been synthesized and characterized. These are the first copolymeric dendrimers composed of a hydrophilic poly(amidoamine) (PAMAM) interior with hydrophobic organosilicon surfaces. These dendrimers have been prepared by surface modifications of an ethylene diamine core PAMAM dendrimer with (3-acryloxypropyl)methyldimethoxysilane, (3-acryloxypropyl)bis(vinyldimethylsiloxy)methylsilane, (3-acryloxypropyl)tris(trimethylsiloxy)silane, chloromethyltrimethylsilane, and chloromethyldimethylvinylsilane, to varying degrees of surface coverage. The obtained products were characterized by 1 H, 13 C, and 29 Si NMR, and by DSC and TGA. The dendrimers with less completely covered organosilicon surfaces are water soluble, and have considerable surface activity, the best of which lowered the surface tension of water to less than 30 mN/m. Areas in their surface, according to the Gibbs adsorption isotherm, are surprisingly small, i.e., of the order of 100 Å2 /mol. More completely hydrophobed dendrimers are water insoluble, and form spread monolayers on water, capable of sustaining surface pressures over 40 mN/m. Areas per molecule are in the 1,000 Å2 /mol range.