Phase Equilibria and Structure Formation in the Polylactic-co-Glycolic Acid/Tetraglycol/Water Ternary System

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Polylactic-co-glycolic acid (PLGA) is a widely used biodegradable polymer.
• Controlling the phase separation of PLGA in solution is crucial for fabricating specific structures.
• Tetraglycol (TG) acts as a hydrophilic solvent for hydrophobic PLGA.

Purpose of the Study:

• To investigate the phase separation and structure formation of PLGA/TG solutions in aqueous media.
• To construct the phase diagram of the ternary PLGA/TG/water system.
• To understand the mechanism of antisolvent-induced phase separation in PLGA/TG/water mixtures.

Main Methods:

• Cloud point methodology
• High-speed video recording
• Differential scanning calorimetry (DSC)
• Optical and scanning electron microscopy (SEM)
• Antisolvent immersion (water and water/TG mixtures)

Main Results:

• The phase diagram of the PLGA/TG/water system was established.
• The PLGA/TG composition causing glass transition at room temperature was identified.
• Detailed analysis of structure evolution under different antisolvent conditions ('harsh' vs. 'soft') was performed.
• Insights into the antisolvent-induced phase separation mechanism were gained.

Conclusions:

• The study provides a fundamental understanding of phase separation in PLGA/TG/water systems.
• This knowledge facilitates the controlled fabrication of diverse bioresorbable structures.
• Potential applications include microparticles, fibers, membranes, and tissue engineering scaffolds.