Water soluble amphiphilic polymers of poly-N-vinylpyrrolidone (PVP) and polyacrylamide (PAA) were synthesized by radical polymerization in the presence of functional mercaptane and introduction of one end heptadecyl or octadecyl group. Polymers form micelles in water solution Polymers were found to be efficient steric protectors of liposomes in vitro and in vivo.