Synthesis and properties of ambient-curable non-isocyanate polyurethanes

The cyclic carbonate polymer (EC-51) was synthesized with diglycidylether of bisphenol A (E-51) and CO2 under 0.6 MPa at 130 °C for 6 h. The EC-51 prepolymers (EC-51-P) carrying cyclic carbonate groups were prepared by EC-51 reacted with isophorone diamine (IPDA), and then NIPU coatings were prepared by EC-51-P cured with PEI at room temperature. The structures and molecular weights of EC-51-P and NIPU coatings were characterized with FTIR and GPC. The GPC results revealed that molecular weights of EC-51-P were ranged from 2000 to 3800 with 1.30-1.55 of the PDI. The influence of IPDA additions on the properties of EC-51-P and NIPUs were investigated and the results showed that EC-51-P could be cured at room temperature, and their NIPU films hardness increased with the increasing of carbonate/IPDA molar ratios accompanying with the glass transition temperatures increasing. The cured films of NIPU displayed high hardness, excellent impact strength, adhesion and flexibility. They also exhibited excellent solvent resistance to toluene, alkali, xylene and alcohol. Meanwhile, cured films had good thermal stabilities with the temperatures of 5% weight loss (T5%) were in the range of 260-292 °C.