MICROSTRUCTURE OF POLYURETHANE IONOMERS DERIVATIZED WITH DODECYLAMINEAND POLYETHYLENE OXIDE IN THE HARD SEGMENT

Segmented polyether-polyurethanes containing sulfonate groups in the h ard segment were modified by the grafting of polyethylene oxide and C- 12 hydrocarbon chains. The grafts were attached via the sulfonate grou ps. The physical properties of the materials, including stress-strain behavior, thermal behavior, and water uptake were studied. Grafting wa s found to alter material behavior significantly. Both the alkyl and p olyethylene oxide grafts appear to alter the packing of the hard segme nts in microdomains because the grafted materials, in contrast to thei r sulfonated precursor, do not exhibit a melting transition. However, the polyethylene oxide chains appear to interact with the hard segment s, probably through hydrogen bonding. For the C-12 grafted materials, differential scanning calorimetry showed that a third microphase, cons isting largely of C-12 chains, may be formed by annealing. Stress-stra in and water uptake data support these interpretations. The grafted ma terials were found to absorb more water than the sulfonated precursor. Most of the water taken up by the C-12 material appears to be bulk wa ter whereas for the PEO material the absorbed water behaves as if it i s bound. (C) 1994 John Wiley & Sons, Inc.