Abstract:Hyperbranched polyglycerol (hPG) with controlled molecular weight and narrow polydispersity has been synthesized by a one-step anionic ring-opening polymerization (ROP) reaction, in which monomer glycidol (2,3-epoxy-1-propanol) was added dropwise to the mixture solution of 1,1,1-tris(hydroxymethyl)propane (TMP) initiator, potassium tert-butoxide (K-t-OBu) base, and anhydrous N-methylpyrrolidone solvent, for the prevention of cyclized byproduct. Three different molecular weight hPGs were synthesized through tailoring the initiator/monomer ratio. Various techniques including 1H-NMR, inverse gated (IG) NMR spectroscopy, gel permeation chromatography (GPC) and fourier transform infrared spectroscopy (FT-IR), were employed to characterize the chemical structure, degree of branching (DB), molecular weight and polydispersity of the synthesized hPG; differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), particle size and zeta analyzer were used to analyze their glass transition temperature (Tg), thermal stability and solution properties, respectively. Results demonstrate that three hPGs were synthesized with targeted molecular mass (1509 g/mol, 4566 g/mol, 11235 g/mol) and polydispersities in the range of 1.82 to 2.05. Importantly, the solvent N-methylpyrrolidone could help to rapidly increase the molecular weight of hPG during the reaction and to improve its mono-dispersity compared to the non-solvent system. Moreover, the glass transition temperature (Tg) and thermal degradation temperature (Td) of hPG was increased slightly with their increasing molecular weight from 1,500 g/mol to 11,200 g/mol.