## 16 Conclusions and Future Outlook  
This review encompasses various strategies adopted by researchers to fabricate porous polymer nanocomposites such as foams and aerogels to suppress electromagnetic interference via the microwave absorption phenomenon. The roles of nanostructured materials such as graphene, carbon nanotubes, MXenes and metal nanowires have been of paramount importance in EMI shielding applications, and the ability of these nanoinclusions to percolate within a polymeric system have inspired researchers to develop higher-performance EMI shielding materials. However, with the advancement of technology, the need for lightweight materials with superior EMI shielding performances has initiated burgeoning interest for porous materials for EMI shielding applications. Hence, designing engineered porous materials is considered as an effective strategy to reduce the overall density of the EMI shield as well as to reduce the percolation threshold of the system. It can also be observed that in all the porous engineered systems, the incoming electromagnetic radiation undergoes multiple internal reflections, and the reflected waves within the pores are eventually absorbed and dissipated as heat energy. Nevertheless, the mechanical properties of these aerogels and foams are also very crucial for their use in practical applications as microwave absorbers. Table 2 illustrated various aerogel/foam compositions reported in the literature for EMI shielding applications, with some key parameters depicting their shielding performance. In the near future, novel 2D materials such as MXene will play a key role in the development of self-assembled and engineered porous materials, which have the potential to deliver higher EMI shielding performances even at lower shielding thickness owing to their higher electrical conductivity and excellent physicochemical properties. The translation of these materials from the lab to industry is yet another hurdle that needs to be addressed in the near future. Hence, ultra-lightweight, robust and commercially viable porous architectures such as nanocomposite foams and aerogels are the most promising candidates for microwave absorption and suppressing electromagnetic pollution.  
Figure 20: Schematic representing the fabrication of MXene/sodium alginate aerogel and its PDMS-coated foam. Reproduced with permission from [164]. Copyright 2020, Elsevier Ltd.  
**Author Contributions:** Conceptualization, writing--original draft preparation, writing--review and editing, data curation, validation, formal analysis, A.R.P.; writing--original draft preparation, writing--review and editing, data curation, N.P.A.; writing--original draft preparation, B.T.; writing--original draft preparation, N.G.; funding acquisition, validation, M.J.; writing--review and editing, funding acquisition, validation, C.P.; funding acquisition, validation, project administration, N.K.; supervision, project administration, funding acquisition, S.T. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by [Ministry of Electronics and IT (MeitY), New Delhi, provided as the Visvesvaraya Ph.D. Scheme for Electronics and IT, Digital India Corporation (Formerly Media Lab Asia)] grant number [PhD-MLA/4(58)/2015-16].  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** A.R.P.; N.K. and S.T. acknowledges the funding from the Ministry of Electronics and IT (MeitY), New Delhi, provided as the Visvesvaraya Ph.D. Scheme for Electronics and IT, Digital India Corporation (Formerly Media Lab Asia) (Ref No: PhD-MLA/4(58)/2015-16) (Unique Awardee No: MEITY-PHD-503). A.R.P. and C.P. would also like to acknowledge the funding from Newton Bhabha Fund, British Council, United Kingdom, provided under the Newton Bhabha Ph.D. placement programme (2019-2020).  
**Conflicts of Interest:** The authors declare no conflict of interest.