A NEW MULTIPLET-CLUSTER MODEL FOR THE MORPHOLOGY OF RANDOM IONOMERS

A new morphological model for random ionomers is proposed which incorporates the findings of recent dynamic mechanical and X-ray scattering studies. The model is based on the existence of multiplets, which reduce the mobility of the polymer chains in their vicinity. The thickness of the restricted mobility layer surrounding each multiplet is postulated to be of the order of the persistance length of the polymer. Isolated multiplets act as large cross-links, thus increasing the glass transition temperature of the material. As the ion content is increased, the regions of restricted mobility surrounding each multiplet overlap to form larger contiguous regions of restricted mobility. When these regions become sufficiently large, they exhibit phase-separated behavior and are termed clusters. The model is in good agreement with a very wide range of experimentally observed phenomena, especially those based on dynamic mechanical and X-ray scattering techniques. © 1990, American Chemical Society. All rights reserved.