Synthesis and drug release properties of poly(ethylene oxide) segmented polysulfone copolymers

A series of poly(ethylene oxide) (PEO) segmented polysulfone copolymers with different PEO content has been successfully synthesized via condensation polymerization of 4,4′-dichlorodiphenylsulfone (DCDPS), chlorine-end-capped poly(ethylene oxide) (PEO-Cl2)) and 4,4′-dihydroxybiphenyl (DHBP) in N,N-dimethylacetamide (DMAc) in the presence of anhydrous potassium carbonate at 160 °C for 20 h. The resulting copolymers showed high molecular weights (Mn = 28,000–40,200 Da) and relatively narrow molecular weight distributions (Mw/Mn = 1.57–1.87). They are well soluble in common organic solvents such as chloroform and tetrahydrofuran. Films with high tensile strength (38–50 MPa) and good elasticity of elongation (elongation at break: 190–430%) were prepared by solution cast from the copolymer solutions in chloroform. Sirolimus and paclitaxel were used as drugs and their release kinetics were investigated. For both drugs, the release rate was strongly influenced by the PEO content of the polymer films, i.e., PSF–PEO films with higher PEO content showed larger drug release rate. Film swelling due to liquid sorption is mainly responsible for the drug release.