1 Review of Fabrication, Characteristics, and Applications of Multi-Scale Polymer Composites 1 This review focuses on the multi-scale polymer composites, their applications, structural characteristics, and manufacturing processes. Using micro or nano-sized particles as fibers, multi-scale composite reinforcements improve the thermal, mechanical, and functional characteristics of polymers in ways that single-scale composites cannot. Several manufacturing procedures are evaluated to attain enough dispersion and significant interfacial adhesion between the reinforcements and the polymer matrix. These are essential for the electronics, automotive, and aerospace sectors to have devices with improved functionality and adaptability. Along with the sustainable design issues that multi-scale polymer composites encounter in order to become high-performance materials, the examination examines interface engineering, scalable production, and property optimization control. 1 7 Farnaz Sadeghi Department of Biomedical Engineering of Islamic Azad University, Central Tehran Branch, Tehran Iran farnazsadeghi_487@yahoo.com Jalaladdin Hosseinzadeh Department of Biomedical Engineering of Islamic Azad University, Central Tehran Branch, Tehran Iran jalal.hosseinzadeh@iau.ac.ir Masoumeh Tabebordbar Department of Polymer Engineering, Faculty of Chemical and Polymer Engineering, Yazd University, Yazd Iran Masoumeh.tabebordbar88@gmail.com Multi-Scale Polymer Composites Thermal Conductivity Electrical Properties Applications [1] R. Volponi, P. Spena, F. De Nicola, L. Guadagno, Multiscale composites: Assessment of a feasible manufacturing process, International Journal of Aerospace Engineering 2019(1) (2019) 6845310.##[2] V. 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