Nonisocyanate thermoplastic polyurethane elastomers based on poly(ethylene glycol) prepared through the transurethanization approach

Nonisocyanate thermoplastic polyurethane elastomers (NIPUs) were synthesized with the transurethanization approach. Dimethyl dicarbamates (DCs) were prepared by the reaction of a diamine with an excess of dimethyl carbonate in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a catalyst. Then, the polymers were obtained under neat conditions through the reaction of DC with polyethyleneglycol of average molecular weight of 1500 g/mol (PEG1500) at variable temperatures in the presence of different amounts of 1,4-butanediol. TBD, dibutyltin dilaurate (DBTL), and K2CO3 were tested as catalysts. TBD and DBTL seemed to be more efficient than K2CO3 in the temperature range 140-160 degrees C. The obtained materials exhibited molecular weight values (M-w) up to 10,000 g/mol and thermal stabilities above 200 degrees C. The soft segments displayed glass-transition temperature values that varied from -49 to -1 degrees C and melting temperature values that varied from 38 to 49 degrees C. Compared to polyurethane analogs, the NIPUs exhibited higher crystallinities and thermal stabilities. (C) 2017 Wiley Periodicals, Inc.