Chitosan-Polyaniline (Bio)Polymer Hybrids by Two Pathways: A Tale of Two Biocomposites

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Polyaniline (PANI)-based biocomposites show promise for humidity sensors and adsorbents.
• Chitosan (CHT) is a versatile biopolymer for composite formation.

Purpose of the Study:

• To investigate different preparation routes for PANI-CHT composites.
• To differentiate between covalent and noncovalent bonding in these composites.
• To understand structure-property relationships for adsorbent and sensor applications.

Main Methods:

• In situ polymerization of aniline with CHT (Type 1).
• Molecular association in acidic aqueous media (Type 2).
• Physical mixing of PANI and CHT powders (Type 3).
• Spectral, thermogravimetric, and 1H NMR analyses.
• Dye adsorption studies.

Main Results:

• Type 1 composites exhibited covalent and hydrogen bonding, leading to reduced water swelling and a more compact structure.
• Structural stability followed the trend: Type 1 > Type 2 > Type 3.
• Dye adsorption and spectral data confirmed the unique properties of Type 1 composites.
• 1H NMR verified covalent bonding in in situ polymerized samples.

Conclusions:

• The preparation method significantly influences the bonding nature and properties of PANI-CHT composites.
• Chitosan acts as a template, enabling variable covalent/noncovalent interactions with PANI.
• Tailored composite design through controlled bonding can enhance adsorbent materials for environmental remediation and humidity sensors.