Shape Memory of Microscale and Nanoscale Imprinted Patterns on a Supramolecular Polymer Compound

Surface memory effects for micropattern and nanopattern are demonstrated for shape memory compounds composed of mixtures of the zinc salt of a sulfonated poly(ethylene-co-propylene-co-ethylidene norbornene) ionomer and three different low molar mass fatty acids (FAs): lauric acid (LA), stearic acid (SA), and zinc stearate (ZnSt). This work shows the ability to tune the surface pattern switching temperature (T_c ) by simply varying the FA melting point. The melting point of the FA in the ionomer compound is depressed from that of the pure FA due to strong dipolar interactions between the ionomer and the FAs. Surface pattern memory and recovery are shown for compounds with 20 wt% LA, SA, or ZnSt, where T_c = 50, 80, and 100 °C, respectively. Recovery efficiencies for micropatterns are better than 92% for all three compounds and 73% for a nanopattern for the ionomer/ZnSt compound.