Synthesis of triazole ring-containing pentol chain extender and its effect on the properties of hyperbranched polyurethane-urea coatings

This article describes the synthesis and property evaluation of different hyperbranched polyurethane-urea (HBPUU) coatings based on a newly synthesized triazole ring-based pentol chain extender. For this initially, the chain extender was synthesized using acetylene azide click reaction and the structure of the intermediate compounds were confirmed by 1H-, 13C-NMR, FTIR, and ESI-mass spectrometry. In the further steps, the required HBPUU coatings were prepared by a systematic three-step reaction process. In the first step, a isocyanate terminated prepolymer resin was synthesized at NCO/OH ratio of 1.2 : 1, while the second and third step involves the partially chain extension followed by moisture curing. The excess NCO content in the prepolymer was calculated by standard dibutylamine titration method and partially (10, 20, 30, 50, and 70% of the excess NCO content) chain extended with the pentol chain extender and remaining was moisture cured. The structure property relation of different HBPUU coating films were analyzed by FTIR peak deconvulation technique using Gaussian curve fitting procedure while, their viscoelastic and thermo-mechanical properties were measured by dynamic mechanical thermal analysis, thermo gravimetric analysis, differential scanning calorimetric, and universal testing machine instruments. These results showed that thermal stability, glass transition temperature (Tg), elongation at break increases but the storage and tensile modulus decreases with increasing the percent loading of the triazole chain extender. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012