Synthesis and properties of allyl terminated renewable non-isocyanate polyurethanes (NIPUs) and polyureas (NIPUreas) and study of their photo-crosslinking

Abstract

Allyl terminated renewable non-isocyanate polyurethanes (NIPUs) and polyureas (NIPUreas) were synthesized using the transurethanization approach. Dimethyl dicarbamate monomers were prepared by the reaction of a diamine with an excess of dimethyl carbonate (DMC). These monomers were reacted with an excess of a diamine to afford amine terminated polyureas. The amine end-groups were converted into allyl groups by reaction with 10-undecenoic acid. NIPUs were prepared by reaction of an excess of dimethyl dicarbamate monomers with a diol, affording methyl carbamate chain-ends, which were converted into ally groups by reaction with 9-decen-1-ol. All the chemical reactions were conducted under neat conditions, in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst. The obtained materials exhibited Tg values varying from −44 to −35°C, Tm values varying from 29 to 201°C, and thermal stabilities above 200°C. The optimal conditions of photo-curing of the prepared materials were determined through a kinetic study of the reaction of the allyl end-groups, in the presence of benzophenone as photoinitiator.