Synthesis and characterization of hyperbranched polyesters and polyurethane coatings |
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Authors: | Savita Kumari Aswini K Mishra Dipak K Chattopadhyay K V S N Raju |
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Institution: | 1. Organic Coatings and Polymers Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 007, India;2. Organic Coatings and Polymers Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 007, IndiaOrganic Coatings and Polymers Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 007, India |
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Abstract: | Polyurethane (PU) coatings are widely used for variety of high‐performance applications in today's coating technology. The emerging hyperbranched polymers having three‐dimensional morphology have opened a new avenue to tailor the architecture of PU coatings. The methodology followed here is based on preparation of PU coatings from hyperbranched polyester. Initially, different hyperbranched polyester polyols (HPs) were synthesized by varying the hydroxyl‐terminated precursors that is, pentaerythritol, trimethylol propane or glycerol and keeping the diacid that is, adipic acid quantity constant at various mole ratios of 1:0.6, 1:0.8, 1:0.9, and 1:1, respectively. The obtained HPs were characterized by nuclear magnetic resonance (NMR) spectroscopy, matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF)‐mass spectrometry, and Fourier transform‐infrared (FTIR) spectroscopy. The degree of branching and the quantity of different structural units present in the various HPs were calculated by integrating the quaternary carbon and carbonyl zone in 13C NMR spectroscopy. The extent of condensation in different HPs was also calculated from 1H NMR spectra. Later on, NCO‐terminated PU prepolymers (NCO‐PU) were synthesized by reacting HPs with isophorone diisocyanate (IPDI) at NCO/OH ratio of 1.6:1. In the third step, the excess NCO content in the NCO‐capped PU prepolymers were reacted with atmospheric moisture and hyperbranched polyurethane (HPU) coatings were formed. The coating films were analyzed by FTIR and dynamic mechanical thermal analysis instruments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2673–2688, 2007 |
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Keywords: | hyperbranched polyols polyurethane NMR FTIR DMTA |
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