Metamaterial-inspired cotton textile functionalized with polyaniline-methylcellulose@rGO-CuS Nanohybrids: Tunable...

In this study, multifunctional polyaniline-methylcellulose@rGO-CuS (PM@rGO-CuS) nanohybrids were synthesized via a facile one-pot method. This approach combined rGO-CuS nanohybrids, aniline monomer, and methylcellulose (MC). By precisely tuning the rGO-CuS fraction, the composite's properties were optimized and thoroughly characterized. The resulting nanohybrids were then applied to cotton fabric in a single-bath process using chitosan (CS). This produced an engineered textile with exceptional electronic properties and a DC conductivity of 4.5 × 10^-5 S/cm. This represents a six-order-of-magnitude enhancement over the original cotton material. Notably, this study presents the first demonstration of tunable negative dielectric permittivity (ε' < 0) in cotton textiles. As a result, the textile behaves as a metamaterial and exhibits advantageous repulsive properties at frequencies below 1 kHz. The fabric also exhibits outstanding mechanical and electromechanical performance, with a significant negative piezoresistive response to strain: resistance decreases upon stretching. Its exceptional Gauge Factor of -5.42 at 2.5% strain enables precise detection of subtle human movements, including speaking, blinking, and breathing. Thus, the dual functionality of PM@rGO-CuS/cotton integrates metamaterial-like electrical properties with enhanced strain sensitivity. This makes it a promising platform for advanced electromagnetic shielding, flexible electronics, and next-generation smart textile applications.