Thermal and thermomechanical properties of hyperbranched polyurethane‐urea/cenosphere hybrids

Hyperbranched polyurethane (HBPU)‐urea/cenosphere hybrid coatings were synthesized by incorporating various concentrations of cenosphere into HB polyester matrix by ultrasonication technique, and this polyester was further used for the preparation of isocyanate terminated HBPU prepolymers by reacting with excess isophorone diisocyanate (IPDI) in a NCO/OH ratio of 1.6 : 1. The desired hybrid coating is obtained by moisture curing the excess NCO present in the prepolymer through film casting. The structure of the hyperbranched polyester (HBPE) was conformed by ¹H, ¹³C NMR and FTIR spectroscopy and the degree of branching (DB) was calculated using Frechet and Frey equations. These hybrid films were characterized by powder XRD, FTIR, SEM, DMTA, and TGA. The structure property correlation, intermolecular/intramolecular hydrogen bonding, the surface morphology, and viscoelastic properties were studied. These results showed an increase in T_g and thermal stability of the hybrid coatings than the base polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008