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<p>Chitosan-based nanocomposite films containing 0–12 wt% AgNO₃ were produced through solution casting to explore how Ag⁺ coordination and the in situ formation of silver-related species shape their structural, mechanical, optical, thermal, and dielectric behavior. FTIR results revealed strong interactions between Ag⁺ ions and the –NH₂/–OH groups of chitosan, which gradually weakened the native hydrogen-bonding network and reduced crystallinity. This trend was supported by XRD patterns showing diminished structural order and the appearance of weak reflections linked to metallic silver species at higher AgNO₃ levels. Mechanically, the films displayed a non-linear response, reaching their best performance at 6 wt% AgNO₃ (UTS ≈ 55&#xa0;MPa; elongation ≈ 11%), likely due to Ag⁺-induced physical crosslinking that enhances stress transfer. Optical measurements showed a clear surface plasmon resonance band at 370–374&#xa0;nm and a steady decrease in band gap from 5.38 to 4.85&#xa0;eV, reflecting the development of localized electronic states and stronger charge-transfer interactions. Dielectric analysis further revealed a shift from dipolar relaxation at low AgNO₃ content to interfacial polarization and hopping-assisted charge transport as silver concentration increased.</p>

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Silver species and Ag⁺ ion coordination in chitosan biopolymer films: structural, optical, dielectric, thermal, and mechanical modulation via AgNO₃ doping

  • 期刊论文

  • 发表日期：

    2026年7月18日

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  • Emad M. Ahmed,
  • Ali A. Alkathiri,
  • Mashael Al-Thagfi

摘要

Chitosan-based nanocomposite films containing 0–12 wt% AgNO₃ were produced through solution casting to explore how Ag⁺ coordination and the in situ formation of silver-related species shape their structural, mechanical, optical, thermal, and dielectric behavior. FTIR results revealed strong interactions between Ag⁺ ions and the –NH₂/–OH groups of chitosan, which gradually weakened the native hydrogen-bonding network and reduced crystallinity. This trend was supported by XRD patterns showing diminished structural order and the appearance of weak reflections linked to metallic silver species at higher AgNO₃ levels. Mechanically, the films displayed a non-linear response, reaching their best performance at 6 wt% AgNO₃ (UTS ≈ 55 MPa; elongation ≈ 11%), likely due to Ag⁺-induced physical crosslinking that enhances stress transfer. Optical measurements showed a clear surface plasmon resonance band at 370–374 nm and a steady decrease in band gap from 5.38 to 4.85 eV, reflecting the development of localized electronic states and stronger charge-transfer interactions. Dielectric analysis further revealed a shift from dipolar relaxation at low AgNO₃ content to interfacial polarization and hopping-assisted charge transport as silver concentration increased.