Cyclotrimerization of diisocyanates toward high-performance networked polymers with rigid isocyanurate structure: Combination of aromatic and aliphatic diisocyanates for tunable flexibility

Abstract

A series of networked polymers bearing isocyanurate moiety was synthesized by cyclotrimerization of diisocyanates, with employing methylenediphenyl 4,4′-diisocyanate and 1,6-hexamethylenediisocyanate (HMDI) in several feed ratios. In spite of the large difference in intrinsic reactivity between these two diisocyanates, their coannulation proceeded efficiently by using sodium p-toluenesulfinate (pTolSO2Na) and 1,3-dimethyl-2-imidazolidinone as a catalyst and a solvent, respectively. The resulting networked polymers were transparent and exhibited excellent thermal stability. In addition, HMDI-rich feed ratios allowed for the formation of networked polymers with increased flexibility. © 2013 Wiley Periodicals, Inc.