Synthesis and characterization of polyurethane-urea clay nanocomposites using montmorillonite modified by oxyethylene-oxypropylene copolymer

Clay organifier with propylene oxide-capped polyethylene glycol (PEG) with amine end group (jeffamines ED600-2003) was synthesized through an ion exchange process between sodium cations in montmorillonite (MMT) and -NH3+ groups in ED600-2003. The d-spacing of organoclay was found to be 1.697-1.734 nm compared to 0.96 nm of pristine MMT. Transmission electron microscopy (TEM) was used to determine the molecular dispersion of the clay within ED600. Polyurethane-urea/montmorillonite (PUU-MMT) nanocomposites were prepared via in situ polymerization from polyethylene glycol (PEG 400) or 1,4 butane diol (1,4 BD), toluene diisocyanate (TDI), jeffamines ED600-2003, and 1-12 wt% of organoclay. Intercalation of PUU into modified clays was confirmed by X-ray diffraction (XRD), scanning electron microscopy, and TEM. The barrier properties were significantly reduced; however, the thermal stability was increased in the nanocomposites as compared to the pristine polymer. Nanocomposites exhibited optical clarity and solvent resistance. The mechanical properties and the glass transition temperature of PUU were improved with the addition of organoclay. The incorporation of silicate layers gave rise to a considerable increase in the storage modulus (stiffness), demonstrating the reinforcing effect of clay on the PUU matrix. Copyright (C) 2009 John Wiley & Sons, Ltd.