Supramolecular structure of crosslinked polyurethane elastomers based on well‐defined prepolymers

Abstract

AbstractThis article provides both quantitative and qualitative evaluations of supermolecular structures present in segmented polyurethane elastomers. This work presents our recent results from investigation of the microdomain morphology of poly‐(ether‐urethanes) based on polyethylene glycol and poly‐(ester‐urethanes) based on poly‐ε‐caprolactone diol with different molecular weight as soft segments and hard segments based on the combination of TDI and triethanolamine or 4,4′,4″‐triphenylmethane triisocyanate (Desmodur RE). Those PU elastomers were obtained not only in a typical one‐step method but also in the prepolymer method with the use of urethane oligomers with controlled molecular weight distribution (MWD). Prepolymers with well‐defined chain structures and narrow distributions of their molecular weights (MWD) $ \overline {M}_w / \overline {M}_n $ = 1.1–1.6 were produced in a multistage method, i.e., in step‐by‐step polyaddition of 2,4‐ and 2,6‐TDI with polyoxyethylenediols or polycaprolactonediols of different molecular weights. Isocyanate oligomers obtained at individual stages were then crosslinked with triethanolamine, whereas hydroxyl‐terminated oligomers were crosslinked with Desmodur RE. Microdomain morphology of the soft and hard‐segments structure was characterized by means of wide‐angle X‐ray scattering and scanning electron microscope. The phase morphology and microdomain crystallinity were investigated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008