the molecular structures of partially cured polyaminopropylsilsesquioxane and aminopropyltriethoxysilane in water have been studies using fourier transform infrared, laser raman and quasielastic laser light scattering spectroscopy. we propose a multiple hydrogen-bonded structure for the intramolecularly interacting amine and silanol groups using isotope exchange experiment and conformational energy calculations. conformational restrictions are rather low for the proposed structure thus suitable for the partially cured solid where there are slight perturbations by the surrounding amine and silanol groups. the o....n distance was experimentally determined to be in the range 2.70 - 2.67a and estimated theoretically as 2.49 - 2.45a. the aminosilane in very dilute solution was found to be mostly monomeric. the isolated monomer-oligomer transition lies around 0.15 by weight and this transition influences the amount of silane uptake by glass fibers. it is also proposed that this phenomenon may be general for surface treatments by silane coupling agents. hydrolyzed aminosilane oligomers exist in part as submicron aggregates which can be broken up by the addition of an alcohol. the neutralized aminosilane hydrolyzed very slowly although it dissolved into water instantaneously. a micelle formation was also proposed. (author)