Polyurethane anionomers. I. Structure properties of polyurethane anionomers

The influence of mono and divalent nontransition and transition metals on the glass transition and mechanical properties of polyurethane anionomers have been investigated. NCO‐terminated prepolymer prepared from 4,4′‐methylene‐bis(phenyl isocyanate) (MDI) and poly(caprolactone) glycol (PCL) was chain extended with dimethylolpropionic acid (DMPA), and the anionomers obtained by neutralization of the prepolymer. The glass transition temperatures of polyurethane anionomers have been studied as a function of the counterion. From simple electrostatic considerations, it is shown that a linear relationship exists between the glass transition temperature and ionic potential (ϕ) for these particular materials. The relation is; Tg = Aϕ + B. The mechanical properties are greatly affected by the type of the counterion, and in some cases, such as monovalent and nontransition metals, the mechanical properties of the anionomers improved by increasing the ionic potential. On the other hand, transition metals containing anionomers exhibited good mechanical properties but no relationship was observed between the mechanical properties and the ionic potential. The extent of water absorption of PU anionomers follows the same relative trends as the tensile strengths of the transition metals with filled and partially filled d‐orbitals.