Polypropylene–MAlN (M = Ti, Cr) interface interactions

We have studied the influence of transition metal (M = Ti, Cr) and nonmetal (N, O) valence electron concentration, surface defects, and radicals on the interaction of polypropylene and cubic M0.5Al0.5N (002) and (111) surfaces using ab initio calculations. For the ideal and defected surface, the work of separation is low and not affected by valence electron concentration, implying weak interactions. Striking differences occur for radicals, where an increase by two orders of magnitude is observed. This may be understood based on the electronic structure. Radicals give rise to strong bonding across the interface and hence strong interactions.