Synthesis of zinc-containing poly(urethane-ether)s based on zinc salt of mono(hydroxypentyl)phthalate

Zinc salt of mono(hydroxypentyl)phthalate, Zn(HPP)2, was synthesized by reacting 1,5-pentanediol, phthalic anhydride and zinc acetate. Zinc-containing poly(urethane-ether)s (PUEs) were synthesized by reacting hexamethylene diisocyanate (HMDI) or toluene 2,4-diisocyanate (TDI) with a mixture of Zn(HPP)2 and poly(ethylene glycol) (PEG300 or PEG400) in dimethylsulfoxide (DMSO) at 95 °C under nitrogen atmosphere using di-n-butyltin dilaurate as a catalyst. Blank PUEs without Zn(HPP)2 were also prepared by reacting PEG300 or PEG400 with HMDI or TDI under similar conditions. The structure of the polymers was confirmed by FT-IR, 1H NMR, 13C NMR, and solid-state 13C-CP-MAS NMR spectra. The zinc-containing polymers were soluble in only highly polar solvents. The inherent viscosity of the zinc-containing PUEs was found to be very low. X-ray diffraction studies revealed that HMDI-based (PUEs) were partially crystalline while TDI based (PUEs) were amorphous. The Tg values of the zinc-containing PUEs were found to be low and range from 5.3 to 7.5 °C. The thermogravimetric analysis revealed the influence of zinc on the initial decomposition and the overall thermal stability of the polymers.