Effects of interface interaction and microphase dispersion on the mechanical properties of PCL/PLA/MMT nanocomposites visualized by nanomechanical mapping

Microphase dispersions and interface interactions are crucial for high performance polymer nanocomposites. However, it remains a challenge to evaluate their effects quantitatively. In this work, poly(ε-caprolactone) (PCL)/poly(lactic acid) (PLA)/montmorillonite (MMT) nanocomposites were chosen as the model nanocomposites, and the effect of MMT on the microphase dispersions and interface interactions were studied and compared with PCL/PLA blends. Using the atomic force microscope (AFM) based nanomechanical mapping, the interface interactions and microphase evolution under tensile were visualized. The Young's moduli map shows a significantly increased interface width of 91.0 ± 15.3 nm for PCL/PLA/MMT nanocomposites compared with 28.7 ± 4.2 nm for PCL/PLA blends. Moreover, the morphology evolution and the onsite changes of microscopic mechanical properties for PCL/PLA/MMT nanocomposites under tensile were visualized and compared with PCL/PLA blends. The results can therefore provide more insights into understanding the complicated toughening mechanism of ternary nanocomposites.