Hierarchical structure and physicochemical properties of plasticized chitosan

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials

Background:

• Chitosan, a biopolymer, is typically processed using casting-evaporation methods.
• Developing alternative processing techniques for chitosan is crucial for its broader application.
• Understanding the structure-property relationships of plasticized chitosan is essential.

Purpose of the Study:

• To develop a melt-based thermomechanical mixing method for plasticizing chitosan.
• To investigate the microstructural, thermal, and thermomechanical properties of plasticized chitosan.
• To correlate the hierarchical microstructure with material properties.

Main Methods:

• Thermomechanical mixing using a batch mixer with lactic acid and glycerol.
• Microstructural analysis via X-ray diffraction, scanning electron microscopy, and optical microscopy.
• Thermal and thermomechanical property assessment using thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis.

Main Results:

• Successful plasticization of chitosan via thermomechanical mixing.
• Decreased crystallinity with increasing plasticizer content (lactic acid, glycerol, water).
• Identification of novel hierarchical structures (amorphous phase, nanofibrils, microfibers) formed under mechanical shear and thermal energy.
• Correlation between microstructure and thermal/thermomechanical properties.

Conclusions:

• Melt-based thermomechanical mixing is an effective method for plasticizing chitosan.
• This method enables the creation of diverse hierarchical structures in plasticized chitosan.
• The developed plasticized chitosan exhibits tunable properties based on its microstructure.