3. Properties of multi-nanolayer films

The property improvements observed in some cases for these multi-nanolayer systems stem from often complex physical phenomena, linked to confinement and/or interfacial mechanisms. It is well known that forcing polymers to evolve in a confined space (in this case, nanolayers) leads to changes in their behavior. For example, the mobility of chains in the amorphous phase is modified, leading to variations in the glass transition temperature. Similarly, confined space modifies crystallization mechanisms, preventing isotropic spherulite growth and inducing preferential orientation. These phenomena depend to a large extent on the polymers used, first and foremost on their intrinsic properties, but also on their compatibility and thus on the presence of an interphase (intermediate zone between the two polymers in contact, presenting specific characteristics different from those of the two polymers...