Determination of poly(epsilon-caprolactone) solubility parameters: application to solvent substitution in a...

Area of Science:

• Chemical Engineering
• Materials Science
• Pharmaceutical Technology

Background:

• REACH regulations mandate replacing toxic chemicals with safer alternatives.
• Methylene chloride is a toxic solvent used in poly(epsilon-caprolactone) (PCL) microencapsulation.
• Developing safer solvents is crucial for sustainable chemical formulations.

Purpose of the Study:

• To identify a less toxic solvent alternative to methylene chloride for PCL microencapsulation.
• To apply Hansen solubility parameters for solvent selection.
• To ensure the alternative solvent can effectively encapsulate therapeutic proteins.

Main Methods:

• Determined PCL's three partial Hansen solubility parameters using group contribution, swelling experiments, and turbidimetric titration.
• Evaluated potential solvents for their ability to dissolve PCL and form W/O/W multiple emulsions.
• Conducted a feasibility test using the selected alternative solvent.

Main Results:

• Anisole was identified as a suitable PCL solvent with lower toxicity than methylene chloride.
• Anisole effectively solubilized PCL and formed the necessary W/O/W multiple emulsion.
• Successful production of PCL microspheres encapsulating a therapeutic protein was achieved.

Conclusions:

• Anisole is a viable, less toxic alternative to methylene chloride for PCL microencapsulation.
• Hansen solubility parameters effectively guide the selection of safer solvents for polymer processing.
• This study demonstrates a feasible method for producing protein-loaded PCL microspheres with an improved environmental profile.