Thermal Properties and Structural Features of Multilayer Films Based on Chitosan and Anionic Polysaccharides

Abstract

This study investigates the thermal and structural properties of multilayer composites based on chitosan (CS) and polyanions with different functionalities, including sodium sulfoethyl cellulose (SEC), sodium alginate (ALG), and sodium hyaluronate (HA). Unlike polyelectrolyte complexes (PECs) obtained by polymer mixing, the formation of a PEC layer by a process of layer-by-layer deposition of oppositely charged polymers is accompanied by the transformation of the CS polymorphic state, and this affects the relaxation and thermal properties of the resulting multilayer composite. X-ray diffraction analysis showed that the formation of the PEC layer in the CS/SEC multilayer film is accompanied by crystallization of the CS chains and the formation of a predominantly anhydrous CS modification. Thermogravimetric analysis of the CS/SEC film registers a high-temperature peak associated with the thermal decomposition of crystalline CS in the PEC composition. According to the dynamic mechanical analysis, the CS/SEC composite was characterized by a single glass transition temperature, indicating a strong interaction between the layers when using SEC (a strong acid salt) as the counterion to CS. For multilayer composites with weak polyacid salts (ALG and HA), the crystallization of CS in the PEC layer is weaker, as reflected in the thermal degradation of these films. A high-temperature peak is recorded in the thermal decomposition of CS/HA and is absent in the case of CS/ALG. Dynamic mechanical analysis of the CS/ALG composite showed two glass transition temperatures close to those of the original polymers, indicating weak PEC formation. The CS/HA composite showed an intermediate response. Thus, the effect of the PEC layer on the properties of the poly-layer composites decreases in the order CS/SEC > CS/HA > CS/ALG.

A Safe-by-Design Approach for the Synthesis of a Novel Cross-Linked Hyaluronic Acid with Improved Biological and Physical Properties

“…DSC is a thermal analysis that provides information on hydration and thermal resistance properties [ 52 , 53 ] of polymers. In Figure 3 , the resulting thermograms of the native HA and HA–Arg are reported.…”

Does the Freeze–Thaw Technique Affect the Properties of the Alginate/Chitosan Glutamate Gels with Posaconazole as a Model Antifungal Drug?

“…In the case of formulations H0 and K0, a shift of endothermic peaks towards lower temperatures was observed. Additionally, peaks with complicated shapes (exothermic peaks at 233 °C and 249 °C in formulation H0 and at 238 °C and 250 °C in K0) overlapping with another endothermic process at 238 °C (H0) and at 240°C (K0) were observed ( Figure 8 a) [ 45 , 46 ]. Dudek et al suggest that ALG exothermic peaks are the result of the polymer backbone degradation in the dehydration process, depolymerization and saccharide ring destruction which might be caused by partial decarboxylation of the protonated carboxylic groups [ 45 ].…”

“…In thermograms, no temperature shifts of POS were observed which suggests no interaction between drug and polymer for all systems ( Figure 8 b). The shape changes of broad endothermal peaks in ALG/CS-G formulations compared to unprocessed ALG and CS-G might be related to interaction between both polymers [ 46 , 48 ]. In addition, thermograms of the H2, HP2 and K2, KP2 formulations did not express peaks of individual ALG and CS-G, which proved the interactions between ALG and CS-G ( Figure 8 a,b) [ 48 , 49 ].…”

Recent Development of Functional Chitosan-Based Hydrogels for Pharmaceutical and Biomedical Applications

“…Chitosan-based physical hydrogels are produced by ion-complex formations with negatively charged molecules such as dicarboxylic acids [ 58 ], citric acid (tricarboxylic acid) [ 59 ], sulfates, phosphates [ 60 ], gallic acid [ 61 ], alginate [ 62 , 63 , 64 , 65 ], pectin [ 66 , 67 ], sulfoethyl cellulose [ 68 ], and hyaluronic acid [ 69 ]. Through the physical interaction between anions of these molecules and cations of chitosan hydrogels can be formed.…”