Unexpected Plasticization Effects on the Structure and Properties of Polyelectrolyte Complexed Chitosan/Alginate...

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Chitosan and alginate are biocompatible polysaccharides with potential in biomedical applications.
• Controlling the structure and properties of these biopolymers is crucial for their effective use.
• Plasticizers can modify polymer properties, but their effects on chitosan/alginate systems are complex.

Purpose of the Study:

• To investigate the impact of glycerol, triacetin, and 1-ethyl-3-methylimidazolium acetate ([C2 mim][OAc]) as plasticizers on bulk chitosan and chitosan/alginate materials.
• To understand how these plasticizers affect the intra- and intermolecular forces, structure, and properties of the biopolymer matrices.
• To evaluate the potential of these modified materials for biomedical applications.

Main Methods:

• Thermomechanical processing of chitosan and chitosan/alginate blends.
• Mechanical testing to assess ductility and strength.
• Analysis of biopolymer recrystallization and thermal stability.
• Microscopy imaging to observe structural changes.

Main Results:

• Glycerol and [C2 mim][OAc] increased chitosan ductility by reducing interchain forces.
• Triacetin suppressed chitosan recrystallization but had minor plasticization effects.
• Triacetin improved mechanical properties and thermal stability of chitosan/alginate by enhancing interactions.
• [C2 mim][OAc] disrupted chitosan/alginate complexation, leading to phase separation and poor mechanical properties.
• Unique structural formations were observed in alginate/ [C2 mim][OAc] systems under electron beam.

Conclusions:

• Plasticizer selection significantly influences the hydrogen bonding and electrostatic interactions in chitosan and chitosan/alginate materials.
• Triacetin shows promise for developing chitosan/alginate materials with desirable mechanical and thermal properties.
• The study highlights the complex interplay between plasticizers and biopolymer matrices for tailored material design.