High‐Performance Polymers: Synthetic Strategies and Pendant Group Engineering for Advanced Electronic, Membrane, and Functional Material Applications

ABSTRACT The integration of functional heterocyclic moieties into polymer frameworks has led to the creation of advanced materials with exceptional thermal, mechanical, electronic, and optical characteristics. This review consolidates systematic developments in the synthesis of high‐performance polymers featuring heterocyclic architectures and pendant functionalities. Various approaches, such as radical polymerization, ring opening metathesis polymerization, reversible addition–fragmentation chain transfer, oxidative electropolymerization, and metal‐catalyzed polycondensation, have enabled the design of structurally diverse polymer frameworks. Methodologies involving the formation of polyazomethine, Schiff base, and thermally rearranged polyimides contribute to the evolution of smart, stimuli‐responsive polymeric platforms. Synthetic post‐polymerization methods such as Click chemistry, grafting, azo coupling, nucleophilic substitution, cycloaddition, and thiol‐ene addition, allowing for fine‐tuning of solubility, thermal stability, and photophysical response. Moreover, a special focus is given to pendant groups such as imidazole, benimidazole, triazole and quarternized pyridinium, coumarin, carbazole, rylene diimides, and fullerenes, which are employed for applications in optoelectronics, membrane fuel cells, and photovoltaic devices. Polymers bearing amphoteric nitrogen, bulky aromatic side chains, and conjugated donor–acceptor segments demonstrate enhanced proton conductivity and dielectric behavior. The foremost discussion emphasizes the structural relationship and effect of the pendant group that drives substantial innovation across multiple domains in advanced material science.