Welding immiscible polymers with a supercritical fluid

Area of Science:

• Materials Science
• Polymer Science
• Chemical Engineering

Background:

• Poor adhesion between immiscible polymers stems from limited interfacial interpenetration.
• Enhanced adhesion and mechanical properties can be achieved by widening the interfacial zone.
• High-pressure fluids can act as common solvents, promoting interpenetration and chain mobility for polymer welding.

Purpose of the Study:

• To investigate the effect of high-pressure supercritical (SC) fluids on the compatibilization of immiscible polymers.
• To analyze how SC fluid compressibility influences interfacial properties.
• To quantify changes in interfacial thickness, density profile, and tension.

Main Methods:

• Utilized gradient theory of inhomogeneous systems.
• Employed the Sanchez-Lacombe equation of state for thermodynamic modeling.
• Calculated interfacial properties for polymer blends with and without SC fluid exposure.

Main Results:

• High-pressure SC fluid decreased interfacial tension and increased interfacial thickness between immiscible polymers.
• The extent of compatibilization was found to be dependent on SC fluid properties.
• Near the critical point, where SC fluid compressibility is maximal, no significant enhancement or negative effects on compatibilization were observed.

Conclusions:

• Supercritical fluids show potential for enhancing polymer adhesion by modifying interfacial characteristics.
• The effectiveness of SC fluids is influenced by their compressibility and proximity to the critical point.
• Further research is needed to optimize SC fluid conditions for effective polymer compatibilization.