a silane or carbosilane dendrimer is modified with bridge moieties and polymer arms attached to the bridges to form hybrid dendrimer - star polymers . the bridge moieties are attached via si — c bonds to the silane or dendrimer . the bridge has one or more reactive groups to which polymer arms are attached . selected reactive groups on the bridge may serve as initiator sites for in situ polymerization of the arms . the polymer arms are of the polyether , polysulfide or polyester type . these arms may have functional groups which allow further modification and attachments . for this type of star polymer , the bridge has been found to increase resistance to hydrolysis at the silane - or dendrimer - arm junction . these star polymers are useful e . g . as viscosity modifiers , component in molding resins , water solubilizer for hydrophobic molecules , surfactants and as carriers for drugs , prodrugs and other biological agents .