Homogeneous isocyanate- and catalyst-free synthesis of polyurethanes in aqueous media

Abstract

We report an efficient and environmentally-friendly method of synthesizing polyurethanes in aqueous solution via an isocyanate- and catalyst-free polymerization process. Five different polyurethanes were synthesized by first activating 1,6-hexanediol and poly(ethylene glycol) with bis(pentafluorophenyl)carbonate, and then polycondensing various ratios of the 1,6-hexanediol/poly(ethylene glycol)-derived activated carbonates with JEFFAMINE. The polymerization process was confirmed by FTIR spectroscopy, ¹H NMR spectroscopy, and gel permeation chromatography (GPC). The melting temperature was linearly dependent on the 1,6-hexanediol/poly(ethylene glycol) ratio, increasing with greater poly(ethylene glycol) content, as confirmed by differential scanning calorimetry (DSC). Similarly, the degree of crystallinity was also directly proportional to the poly(ethylene glycol) content.