Polyurethane macroazoinitiators based on 2,2?-azobis (2-cyanopropanol) kinetic studies

Abstract

2,2'-Azobis(2-cyanopropanol) (ACP) was used to react with 4,4'-methylene diphenyl diisocyanate (MDI) and α,ω-hydroxy polycaprolactone (PCL) in the presence of dibutyltin dilaurate (SnDBDL) as a catalyst in a two-stage polycondensation to produce a polyurethane macroazoinitiator (PUMAI). The kinetics of the reaction of ACP with a monoisocyanate (para-tolylisocyanate, p-TI) was followed using high performance liquid chromatography. The condensation reaction was performed in 2-butanone, with SnDBDL as catalyst. Kinetic models were suggested to calculate rate constants. The experimental results showed an autocatalytic effect of the reaction by urethane groups and a different reactivity of the second OH group of ACP after the reaction of the first one. The kinetics of the reaction of MDI with ACP and PCL were studied using size exclusion chromatography. Polycondensation was performed under the same conditions used for the model system. The reaction rates of MDI with ACP and PCL were compared. ACP was shown to be slightly more reactive with MDI than PCL. The first stage of PUMAI synthesis (reaction of ACP with a large excess of MDI) was studied. Some side reactions with isocyanates occured. Finally, a typical PUMAI was synthesized.