Polyelectrolyte complexes (PECs) obtained from chitosan and carboxymethylcellulose: A physicochemical and microstructural study

Effects of chitosan (CHS) to carboxymethylcellulose (CMC) mixing ratio (1:0; 4:1; 3:1; 2:1; 1:1; 1:2; 1:3; 1:4; 0:1), temperature (25; 45; 65; 85 °C), and pH (3.0; 3.5; 4.0; 4,5) on obtaining of macro- and micro-polyelectrolyte complexes (PEC) were investigated. Mixing ratio 1:2 and 25 °C maximized the biopolymers' interactions and the formation of macro-PECs (macroscopic structures), independent of the pH. Both macro- and micro-PECs (dispersed microscopic structures) were studied by SEM, FT-IR, XRD and TGA. Micro-PECs had a more homogeneous appearance, whereas macro-PECs presented porous network structures interspersed with heterogeneous-sized vacuoles. Attractive electrostatic interactions and hydrogen bonds were involved in PECs formation. Macro-PECs were amorphous, which is desirable for encapsulating technologically relevant compounds. Finally, macro-PECs had low thermal degradation rates, and micro-PECs were thermally more stable than the forming biomolecules separately. Therefore, both macro- and micro-PECs formed by CHS and CMC appeared as green materials for different techno-functionalities, some of which are currently being studied by our team.