Synthesis and characterization of ordered polyurethanes from a pair of diisocyanate monomers and ethylene glycol

We have studied the synthesis of ordered polyurethane from 4,4'methylenebis (phenyl isocyanate) (MDI), hexamethylene diisocyanate (HMDI) and ethylene g lycol (EG). It was found that the regularity of polyurethanes was affected by the feed speed of the monomer and catalyst species. Using a triethylamin e (TEA) catalyst, a multi-block copolymer was produced by the slow addition of EG to a mixture of MDI and HMDI, and a statistical copolymer was obtain ed by the rapid addition of EG to a mixture of MDI and HMDI. On the other h and, the rapid addition of EG to a mixture of MDI and HMDI in the presence of an alkyltin catalyst produced an alternating copolymer. The structural r egularity of the polymers has an effect on their thermal properties and cry stallinity.