Effects of track overlapping on ion-track grafting reactivity

The effects of ion-track overlapping on the ion-track grafting reactivity, which governs the properties of the resulting functional films, were investigated using a model reaction of a vinyl benzyl chloride monomer into poly(ethylene-co-tetrafluoroethylene) base films irradiated with 560 MeV 129Xe and 330 MeV 40Ar. Electron spin resonance analysis showed that a higher linear energy transfer of 560 MeV 129Xe led to a lower radical concentration, probably due to the high probability of radical recombination. The radical concentration showed a linear relationship as a function of the dose, whereas the degree of grafting (DG) showed a saturated trend at higher doses for both Xe and Ar ions. The local grafting density, defined by dividing the DG by the fluence, began to decrease from a certain fluence, which signified a higher probability of track overlapping.