Structure and segmental dynamics heterogeneity in hybrid polycyanurate-polyurethane networks

Structure and segmental dynamics (at 140-600 K) in a series of hybrid mater ials with regularly varied composition, based on polycyanurate (PCN) networ ks and linear polyurethane (PUR), were studied by infrared spectroscopy, sm all-angle X-ray scattering, differential scanning calorimetry, and laser-in terferometric creep rate spectroscopy (CRS) techniques. Hybridization effec t via cyanate/urethane group chemical interaction was evidenced in these sy stems and that led to formation of a completely homogeneous structure on a scale of > 2 nm, irrespective of material composition. At the same time, co mbined CRS/differential scanning calorimetry analysis indicated the pronoun ced nanoscale (less than or equal to2 nm) dynamic heterogeneity within or b elow the extraordinarily broad glass transition in these single-phase mater ials. Discrete CRS analysis of constituent motions, associated with the pre dicted kinds of polyurethane segmental relaxations (cooperative and noncoop erative) and with the dynamics in differ entry cross-linked PCN network sec tions, has been performed.