A comprehensive review on synthesis and application of MAX/MXenes as 2D nanoreactants with a glance at the modification of materials

MXene modification of polymeric materials represents a promising frontier for the development of advanced functional composites, particularly in smart textiles, flexible electronics, and multifunctional coatings. By exploiting MXene surface-active groups, metallic conductivity, and mechanical reinforcement capabilities, MXene–polymer systems can deliver high electromagnetic interference (EMI) shielding effectiveness often exceeding 40 dB at sub-millimeter thickness, electrical conductivities above 103 S cm−1, and strain sensitivities with gauge factors above 9000 in optimized textile-based sensors. This review systematically surveys MAX phases as layered precursors, their synthesis routes, and their conversion into MXenes via top-down etching and emerging bottom-up chemical vapor deposition, with emphasis on safer, fluoride-free, and scalable processes. Particular attention is given to in situ characterization and first-principles calculations, which together clarify structural evolution, surface terminations, and property tuning during the transformation of MAX into MXene. The paper then critically compares MXene-based electronic, sensing, environmental, and biomedical applications, highlighting representative performance metrics such as ∼72 °C thermal regulation over thousands of seconds in MXene textile heaters and 90–91% optical transmittance combined with conductivities of around 3092 S cm−1 in transparent conductive electrodes. Three major contributions distinguish this work: (i) integrating MAX synthesis, MXene etching/delamination strategies, and MXene–polymer systems within a single framework; (ii) emphasizing relatively low-hazard, industrially relevant processing routes; and (iii) identifying key challenges in oxidation stability, environmental compatibility, and long-term mechanical durability of MXene-polymer composites. These insights provide a roadmap for designing next-generation MAX/MXene nanoreactants and MXene-modified polymeric materials for high-performance, real-world devices.