Water Soluble Polysiloxanes

Water soluble polysiloxanes were prepared by condensation of 3-aminopropyl diethoxymethylsilane followed by the reaction of the amines with ethylene carbonate to yield carbamate side chains with terminal hydroxyl groups attached to each silicon atom in the polymer chain. The molecular weight of these carbinol functional polysiloxanes was controlled by adding known concentrations of hexamethyldisiloxane during the polycondensation reaction. The structure of these polymers was confirmed by H-1 NMR and FTIR. The resulting polysiloxanes are water soluble and their solubility is independent of the pH or the molecular weight of the polymer. Furthermore, no additives are needed in the water to enhance the solubility of these polymers. The mechanical properties of films that were cast from water solutions were studied and indicated the presence of strong hydrogen bonds that provide for elastomeric films with no need for additional crosslink agents. The hydrophilic nature of the polymer was further confirmed by contact angle measurements and thermal properties data clearly indicate the presence of bound water associated with the large number of hydroxyl groups in the polymer. SEM images of paper coatings prepared from these polysiloxanes revealed a smooth surface with no apparent structural defects that can be used as an anti-graffiti coating.