Dissolution dynamics of a binary switchable hydrophilicity solvent-polymer drop into an acidic aqueous phase

Area of Science:

• Green Chemistry
• Materials Science
• Chemical Engineering

Background:

• Switchable hydrophilicity solvents (SHSs) are tunable solvents that transition between hydrophobic and hydrophilic states when exposed to an acidic trigger like CO2.
• SHSs present a sustainable alternative to volatile organic compounds (VOCs) in industrial processes due to their reduced flammability and ease of recovery.
• Understanding the dissolution dynamics of SHS-based systems is crucial for optimizing extraction and particle formation processes.

Purpose of the Study:

• To investigate the dissolution dynamics and in-drop phase separation of a polymer-containing SHS drop triggered by an acid.
• To establish a relationship between drop dissolution time, initial volume, and experimental parameters.
• To elucidate the mechanism of polymer particle formation during SHS dissolution.

Main Methods:

• Experimental study of SHS drop dissolution under acidic conditions across 70 different experimental parameters.
• Quantitative analysis of dissolution time and correlation with initial drop volume.
• In-situ observation of in-drop phase separation and final particle morphology.

Main Results:

• A scaling relationship was identified between drop dissolution time and initial volume, with a scaling coefficient of approximately 0.53.
• Shorter dissolution times were observed with decreased aqueous phase pH or increased initial polymer concentration.
• In-drop phase separation was confirmed, leading to the formation of porous polymer particles.

Conclusions:

• The study provides a detailed microscopic understanding of SHS drop dissolution dynamics.
• Findings offer insights for designing efficient SHS extraction processes for controlled polymer particle formation.
• The identified scaling relationship and influencing factors can guide process optimization in green chemistry applications.