A Non-isocyanate route to poly(ester urethane) with high molecular weight: Synthesis and effect of chemical structures of polyester-diol

A series of non-isocyanate linear high molecular weight poly(ester urethane) (PETU) were prepared through an environmentally-friendly route based on dimethyl carbonate, 1,6-hexanediol and 1,6-hexanediamine. In this route, the polyurethane diol was first prepared by the reaction between Bis-1,6-hexamethylencarbamate (BHC) and 1,6-hexanediol. Series of polyester soft segment of polyurethane have been synthesized from the polycondensation of adipic acid and different diols, including butanediol, hexanediol, octanediol and decanediol. The subsequent polycondensation of polyurethane diol and polyester diol led to linear PETUs. The polymers were characterized by GPC, FT-IR, 1H NMR, 13C NMR, DSC, WAXD, TGA and tensile testing. The results indicated that PETUs possess weight-average molecular weight higher than 100, 000 and the tensile strength as high as 10 MPa. The thermal properties, crystallization behavior, micro phase separation behavior and morphology were studied by DSC and AFM, and the results indicate that degree of phase separation is affected by two factors, the crystallization and hydrogen bonding interaction between soft segment and hard segment.