series of polyurea block copolymers based on either aminopropyl terminated cyano-containing polysiloxane or polydimethylsiloxane soft segments was synthesized. The hard segments consisted of 4

4'-methylenediphenylene diisocyanate chain extended with ethylenediaAnne.The hydrogen bond and the morphology of these block copolymers were studied by FT-IR

NMR and DMA. These materials exhibited microphase separation of the hard and soft segments

and the microdomains may change greatly in different systems due to the difference of the hydrogen-bond in these block copolymers. The hydrogen-bond in the cyano-containing polusiloxane-polyurea block copolymers was not only in the hard segment domains but also in the interphase between the solt and hard segments;attaching polar cyano side groups along the prlysiloxane chains promoted phase mixing in comparison with polydimethylsiloxane-based polyurethanes.The hydrogen-bond between the soft and the hard segments increased with the increase of the thickness of the interphase.The observation also showed that the hydrogen-bond in the block copolymers was affected by the concentration and the temperature of the solution.