Molecular mobility, composition and structure analysis in glycerol plasticised chitosan films

Area of Science:

• Materials Science
• Polymer Science
• Biomaterials

Background:

• Chitosan films are widely used due to their biocompatibility and biodegradability.
• Plasticisers like glycerol are often incorporated to improve film flexibility and mechanical properties.
• Understanding the relationship between plasticiser concentration and film characteristics is crucial for optimizing material performance.

Purpose of the Study:

• To investigate the impact of polysaccharide/plasticiser concentration on the microstructure and molecular dynamics of chitosan/glycerol films.
• To elucidate the role of glycerol concentration in determining film composition and thickness.
• To analyze the molecular mobility of water and glycerol within the chitosan matrix.

Main Methods:

• Preparation of chitosan/glycerol films with varying compositions.
• Characterization of film composition, thickness, and water activity.
• Microstructural analysis using Transmission Electron Microscope (TEM) imaging.
• Molecular dynamics investigation using Nuclear Magnetic Resonance (NMR) spectroscopy.

Main Results:

• Glycerol quantities in film-forming solutions dictated the final film composition.
• The ratio of chitosan to glycerol determined film thickness and, consequently, microstructure, as confirmed by TEM.
• NMR analysis revealed distinct molecular behaviors: water molecules exhibited free movement, whereas glycerol molecules were primarily bound to the chitosan chains.

Conclusions:

• The concentration and ratio of plasticiser significantly influence the structural and compositional properties of chitosan films.
• TEM and NMR are effective techniques for characterizing the microstructure and molecular dynamics of polymeric films.
• The differential mobility of water and glycerol within the chitosan matrix provides insights into plasticiser-polymer interactions.