Synthesis, characterization and aqueous dispersion of dextran-g-poly(1,4-dioxan-2-one) copolymers

A novel biodegradable graft copolymer, dextran-g-poly(1,4-dioxan-2-one) (PODEX), was synthesized through the ring-opening polymerization (ROP) of 1,4-dioxan-2-one (PDO) onto a dextran backbone. Initially, dextran was silylated with 1,1,1,3,3,3-hexamethyldisilazane. The grafting from pathway was conducted with various (30-70) PDO/OH feed ratios to obtain PODEX copolymers with a various PPDO graft structures. Graft copolymers were characterized by FT-IR, ¹H and ¹³C NMR, DSC, TGA, and WAXD. Molecular weights of the PODEX copolymers (M_W: 94,700-117, 300 Da), glass transition temperature (-29 to -17 °C), melting temperature (82-100 °C), and crystallinity (32-40%) were increased with the content of PPDO. AFM observations revealed that polymeric micelles were spherical and uniform in morphology with around 30-58 nm diameter. Critical micelle concentration (CMC) of self-assembled system was significantly decreased from 3.2 to 1.09 mg/L with the increment of PPDO.