Should polymer nanocomposites be regarded as molecular composites?

In this article, the authors present their point of view on whether an analogy can be drawn between nano and classical microcomposites. Their opinion corresponds with a 25-year-old opinion article by Calvert and is based on their own extensive studies and a large body of studies in the scientific literature. They propose that polymer nanocomposites are in fact quasi-homogeneous molecular blends, which ought to be regarded as molecular composites or self-reinforced polymers. Hence, the micromechanical models of classical composites may not generally apply to nanocomposites, where—instead—the interactions on a molecular scale between the nanoparticles and the polymer matrix control the properties. A few examples, including of nucleation and confinement by nanoparticles, are discussed.