Abstract
We have studied the synthesis of ordered polyurethane from 4,4′-methylenebis(phenyl isocyanate) (MDI), hexamethylene diisocyanate (HMDI) and ethylene glycol (EG). It was found that the regularity of polyurethanes was affected by the feed speed of the monomer and catalyst species. Using a triethylamine (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 obtained by the rapid addition of EG to a mixture of MDI and HMDI. On the other hand, 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 regularity of the polymers has an effect on their thermal properties and crystallinity.
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