The Structural and Electrical Properties of Carboxymethyl Cellulose–Chitosan Composite Films

Abstract

Carboxymethyl cellulose (CMC) is a polysaccharide polymer derived from plant fibrous tissues, while chitosan (CS) is a biopolymer obtained from chitin present in the exoskeletons of crustaceans and insects, as well as fungal cell walls. This study focuses on the synthesis and characterization of CMC, CS, and their composite films (CMC–CS), with emphasis on how material integration influences structural and electrical properties. The films were fabricated using a solution casting technique followed by a triple-cycle freeze-thaw process to enhance structural stability and reduce solubility. Fourier Transform Infrared (FTIR) analysis confirmed successful interaction between the polymers, evidenced by a peak shift to 3346 cm-1 for the CMC-CS composite, indicating strong intermolecular hydrogen bonding between hydroxyl (OH) and amino (NH2) groups. Additionally, the merging of peaks at 1560 cm-1 suggests electrostatic attraction between the anionic carboxylate groups of CMC and the cationic amino groups of CS. This interaction contributes to improved compatibility and structural integrity of the composite films. Electrical characterization demonstrated that the CMC-CS composite films exhibited the highest electrical conductivity, with conductivity increasing linearly as a function of applied current. In contrast, pure CMC showed the highest resistivity. The enhanced electrical performance of the composite is attributed to synergistic interaction between CMC and CS, which facilitate more efficient charge transport pathways. Overall, the findings indicate that CMC–CS composite films possess promising potential for applications in conductive biopolymer systems, particularly in environmentally friendly and flexible electronic materials.