Effect of Crosslinking on Shape-Memory Behavior of Zinc Stearate/Ionomer Compounds

Shape memory polymers (SMPs) based on blends of fatty acid or fatty acid salts and an elastomeric ionomer, sulfonated poly{ethylene-r-propylene-r-(5-ethylidene-2-norbornene)} are described. The permanent network is formed by nanophase separation of intermolecularly associated metal sulfonate groups, and the temporary network is developed by dispersed fatty acid crystals with strong dipolar interactions with the ionomer. The permanent network, however, creeps under load. SMPs with fixing efficiencies >95% and shape recovery efficiency of approximate to 100% were achieved by covalently crosslinking the ionomer.