A Multi-Scale Approach to Microencapsulation by Interfacial Polymerization

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Chemistry

Background:

• Microencapsulation via interfacial polymerization is crucial for delivering fertilizers, pesticides, and drugs.
• Optimizing microcapsule properties requires understanding variations across molecular, microscopic, and macroscopic scales.
• Simultaneous consideration of product and process variables is key to effective microcapsule design.

Purpose of the Study:

• To investigate the impact of formulation, composition, and pH on microcapsule properties.
• To evaluate a novel method for measuring microcapsule compressive strength.
• To explain microcapsule aggregation phenomena based on reaction kinetics and thermodynamics.

Main Methods:

• Multi-scale analysis of microencapsulation by interfacial polymerization.
• Quantification of formulation, composition, and pH effects on microcapsule characteristics.
• Testing a suspension-based method for assessing microcapsule compressive strength.

Main Results:

• Higher amine functionality leads to stronger crosslinking, reducing xylene release rate and improving microcapsule compression force and appearance.
• High initial amine concentrations result in elevated pH, causing microcapsule agglomeration.
• The tested compressive strength measurement method showed low sensitivity to formulation and composition differences.

Conclusions:

• Microcapsule properties are significantly influenced by amine functionality, crosslinking, and pH.
• Aggregation can be explained by kinetic and thermodynamic controls during polymerization.
• The pH measurement method is unsuitable for studying polymerization kinetics due to accounting for side reactions like carbamate formation.
• The developed compressive strength test requires further refinement for practical application in formulation analysis.