Novel pH-sensitive poly(silamine) hydrogel microsphere possessing a stableskin layer

New silicon-based polycationic microspheres, which consist of alternating 3 ,3-dimethyl-3-silapentamethylene and N,N'-diethylethylenediamine, were prep ared. The deswelling of the poly(silamine) microspheres by means of pH-jump experiments revealed the formation of an extremely stable skin layer. The layer could be kept at the interface between particle core and U and shows a significantly different chemical layer. This may be explained by a limite d osmotic-pressure wave due to the high activation energy associated with t he conformational changes.