Polyelectrolyte complexes (PECs) obtained from chitosan and carboxymethylcellulose: A physicochemical and microstructural study
Danielle Cristine Mota Ferreira, Sukarno Olavo Ferreira, Elson S. Alvarenga, Nilda de Fátima Ferreira Soares, Jane Sélia dos Reis Coimbra, Eduardo Basílio de Oliveira
Abstract
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.