In this talk, a state of the art on the recent advances on multilayer coextrusion and the governed interfacial phenomena will be addressed. More specifically, we will deal with the interfaces/interphases of multi micro-/nanolayered polymer films fabricated by forced-assembly multilayer coextrusion technology. There are numerous recent reports dealing with multilayer polymer films from multilayer coextrusion but most of them are only focused on the structure and properties of multilayer films. In our recent works, effects of the triggered interface/interphase in multi micro-/nano-layered polymer structures were studied on compatible multilayers (PVDF/PMMA), reactive multilayers (PVDF-g-MAH/PA6) in comparison to the non-reactive one (PVDF/PA6). Multi-micro and mono-layered architectural films were obtained by forced assembly coextrusion process. Therefore, this summary is focused on a fundamental study of the role of interphase in rheology, dynamics and microstructure of multilayered films (or systems). The work proceeded from the diffuse interphase in compatible multilayered systems to the reactive interphase in reactive counterparts. Therein, we investigated systematically the layer architecture/structure, morphology by WAXS/SAXS, dielectric properties, charge transport dynamics, and especially the uniaxial extensional rheology whereas some surprising strain hardening is highlighted with confinement. Our findings are aimed at a better understanding of the interfacial properties towards controlling the interface/interphases in the present micro-nanostructured polymers for their advanced applications in our daily life such us (i.e., capacitors, energy storage devices, printable electronics, capacitors, energy, nano-medicine, automotive and construction etc). J. Rheol., 2016 and Ind. Eng. Chem. Res. 2018, Soft Matter, 2016, 2017, I&ECR 2020 and Macromolecules 2013;