Probing the urea hard domain connectivity in segmented,non-chain extended polyureas using hydrogen-bond screening agents

摘要

The effects of long-range connectivity between urea hard domains on the microphase morphology and mechanical properties of novel,segmented,non-chain extended polyureas based on single isocyanate molecules were analyzed.This was achieved by systematic disruption of the intermolecular bidentate hydrogen bonding between the urea hard segments by the incorporation of a hydrogen bond screener,LiCl.A systematic decrease in the breadth of the service temperature window and mechanical properties of the polyureas were observed in the presence of LiCl,due to the disruption of the long range connectivity between the hard segments.The above mentioned effects were also found to be dependent on the symmetry of the diisocyanate hard segments.