Analytical investigation of electrically conducting 3-d soft material triggered by conc.HNO₃

This study presents the fabrication of polyaniline–polyacrylamide (PANI–PAM) composite hydrogels through the radical-oxidative polymerization of polyaniline within an insulating hydrogel matrix featuring variable pore sizes. The incorporation of PANI into the pores imparts electroactive properties to the resulting composite material. Field Emission Scanning Electron Microscopy (FESEM) was used to investigate the morphology and distribution of PANI particles embedded in the semi-transparent, colored hydrogel network. Cross-linked polyacrylamide(cPAM) and polyaniline (PANI) are the most widely used materials in this context due to the accessibility of their monomers, simplicity of synthesis, and desirable mechanical and electrical properties. Their combination enhances both sets of properties, with cPAM contributing flexibility and PANI providing electrical conductivity. Typically, the composite is synthesized by forming the hydrogel via radical polymerization—often using redox initiators followed by the oxidative polymerization of aniline within the gel matrix. The resulting structure is often described as a semi-interpenetrating polymer network (s-IPN), where linear PANI chains permeate the cPAM framework. However, evidence suggests that the nanopores in these hydrogels may actually exhibit microporous characteristics. This work will explores recent advancements in these nanocomposite hydrogels (NCHs), discussing current theories of electrical conduction, identifying challenges, and highlighting strategies to enhance conductivity in such hybrid systems.