new styrene - functional polysiloxanes are described which are obtained by reaction of aminoalkyl functional polysiloxanes with styrene isocyanates . the styrene functional urea polysiloxanes have improved hydrolytic stability and are useful , either by themselves or in combination with copolymerizable comonomers , in uv - or heat curable biocompatible and oxygen permeable coatings , films or shaped articles , especially in form of oxygen permeable contact lenses .