Polyphosphoesters: Synthesis, Functionalization And Biomedical Application

Polyphosphoesters is a novel biodegradable materials with a rapid development in recent years.The properties of good biocompatibility and easily modification make this polymer can be widely applied in drug delivery,tissue engineer and gene therapy.Methyl ethylene phosphate(MEP) and ethyl ethylene phosphate(EEP) have been copolymerized with CL catalyzed by lanthanide tris(2,6-di-tert-butyl-4-methylphenolate)[La(DBMP)₃],and random copolymers with high yields and molecular weights were prepared.With the increasing of phosphoester contents,the copolymers show a lower melting temperature(T_m), crystallizing temperature(T_c),glass transition temperature(T_g) and enhanced hydrophilicity.Functionalized cyclic phosphoesters[chloride ethyl ethylene phosphate(CEEP) and propargyl ethylene phosphate(PEP)]were synthesized and copolymerized with CL catalyzed by La(DBMP)₃.Both of the two kinds of copolymers have been successfully quarternzied by either amines[poly(CL-co-CEEP)]or bromoalkane after "click" reaction with DMEAN₃[poly(CL-co-PEP)].Novel amphiphilic heterograft copolymers were synthesized by the ring-opening polymerization of CL,phosphoester functionalized PEG(phosPEG) and PCL(phosPCL) catalyzed by Sn(Oct)₂.The heterograft structure and thermal properties of these copolymers with various compositions were well characterized. These amphiphilic copolymers could self-assemble into spherical micellar structures in aqueous solution with particle size ranging from 20 to 60 nm,and their critical micellization concentrations(CMC) were determined to be 0.69-1.25 mg/L.