Structure and segmental dynamics heterogeneity in hybrid polycyanurate-polyurethane networks

摘要

Structure and segmental dynamics (at 140-600 K) in a series of hybrid materials with regularly varied composition, based on polycyanurate (PCN) networks and linear polyurethane (PUR), were studied by infrared spectroscopy, small-angle X-ray scattering, differential scanning calorimetry, and laser-interferometric creep rate spectroscopy (CRS) techniques. Hybridization effect via cyanate/urethane group chemical interaction was evidenced in these systems and that led to formation of a completely homogeneous structure on a scale of > 2 nm, irrespective of material composition. At the same time, combined CRS/differential scanning calorimetry analysis indicated the pronounced nanoscale (less than or equal to2 nm) dynamic heterogeneity within or below the extraordinarily broad glass transition in these single-phase materials. Discrete CRS analysis of constituent motions, associated with the predicted kinds of polyurethane segmental relaxations (cooperative and noncooperative) and with the dynamics in differ entry cross-linked PCN network sections, has been performed. [References: 52]