Synthesis and properties of hyperbranched polyurethanes,hyperbranched polyurethane copolymers with and without ether and ester groups using blocked isocyanate monomers |
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Authors: | Mahalingam Vanjinathan A Shanavas A Raghavan A Sultan Nasar |
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Institution: | 1. Department of Polymer Science, University of Madras, Guindy Campus, Chennai 600 025, India;2. Department of Polymer Science, University of Madras, Guindy Campus, Chennai 600 025, IndiaDepartment of Polymer Science, University of Madras, Guindy Campus, Chennai 600 025, India |
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Abstract: | Starting from 3,5‐diamino benzoic acid, 2‐hydroxy propyl3,5‐bis{(benzoxycarbonyl)imino}]benzyl ether, an AB2‐type blocked isocyanate monomer with flexible ether group, and 2‐hydroxy propyl3,5‐bis{(benzoxycarbonyl)imino}]benzoate, an AB2‐type blocked isocyanate monomer with ester group, were synthesized for the first time. Using the same starting compound, 3,5‐bis{(benzoxycarbonyl)imino}benzylalcohol, an AB2‐type blocked isocyanate monomer, was synthesized through a highly efficient short‐cut route. Step‐growth polymerization of these monomers at individually optimized experimental conditions results in the formation of hyperbranched polyurethanes with and without ether and ester groups. Copolymerizations of these monomers with functionally similar AB monomers were also carried out. The molecular weights of the polymers were determined using GPC and the values (Mw) were found to vary from 1.5 × 104 to 1.2 × 106. While hyperbranched polyurethanes having no ether or ester group were found to be thermally stable up to 217 °C, hyperbranched poly(ether–urethane)s and poly(ester–urethane)s were found to be thermally stable up to 245 and 300 °C, respectively. Glass transition temperature (Tg) of polyurethane was reduced significantly when introducing ether groups into the polymer chain, whereas Tg was not observed even up to 250 °C in the case of poly(ester–urethane). Hyperbranched polyurethanes derived from all the three different AB2 monomers were soluble in highly polar solvents and the copolymers showed improved solubility. Polyethylene glycol monomethyl ether of molecular weight 550 and decanol were used as end‐capping groups, which were seen to affect the thermal, solution, and solubility properties of polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3877–3893, 2007 |
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Keywords: | hyperbranched poly(ester– urethane)s hyperbranched poly(ether– urethane)s hyperbranched polyurethanes hyperbranched polyurethane copolymers |
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