Effect of Compatibilizers on Polymer Blend Interfaces

Polymer blends demonstrate improved rheological and mechanical properties but are difficult to mix due to high energy interfaces between the components. This results in significant mechanical weakness but can be mediated by using compatibilizers. Despite the large number of studies on the effect of copolymer compatibilizers, the effect of adding sheet-like compatibilizers (for e.g., nanoclay) has not been investigated computationally. Experiments have shown that sheet-like fillers are effective, but the exact mechanisms are unknown. Here, we use coarse-grained molecular dynamics simulations to determine the effect of diblock copolymers and sheet-like compatibilizers at polymer blend interfaces. Our results indicate that sheet fillers that have equal affinity to either polymer in a binary blend, can produce a larger reduction of interfacial tension when compared to diblock copolymers at equal volume fractions. However, the localization of sheet fillers at the interface can be a possible limiting factor. We attempted to bracket sheet filler behavior by either allowing them to localize at the interface or migrate to the bulk polymer phase. We also showed that sheet fillers reduce slip, thus providing for improved stress transfer across the interface, leading to a stronger blend.