The effect of reactor geometry on frontal polymerization spin modes

Area of Science:

• Polymer Chemistry
• Chemical Engineering
• Nonlinear Dynamics

Background:

• Frontal polymerization offers a unique method for rapid material synthesis.
• Understanding the complex dynamics of frontal polymerization is crucial for controlling material properties.
• The interplay of reaction kinetics, heat transfer, and fluid dynamics governs polymerization front behavior.

Purpose of the Study:

• To investigate the influence of reactor geometry and monomer composition on frontal polymerization dynamics.
• To identify and characterize novel instabilities and modes in frontal polymerization systems.
• To explore the relationship between viscosity, monomer ratio, and the emergence of complex behaviors.

Main Methods:

• Utilized reactors of varying sizes and geometries (cylindrical, square, conical).
• Studied frontal polymerization of 1,6-hexanediol diacrylate (HDDA) and pentaerythritol tetraacrylate (PETAC) with ammonium persulfate initiator.
• Employed experimental observations and linear stability analysis to interpret results.

Main Results:

• Observed complex frontal polymerization behavior dependent on monomer ratio, including nonplanar fronts and spin modes.
• Confirmed increased "hot spots" with larger reactor diameters and observed a novel "zig-zag" mode in square reactors.
• Demonstrated viscosity-dependence of spin mode instabilities and identified new modes in complex reactor geometries.

Conclusions:

• Frontal polymerization dynamics are highly sensitive to reactor geometry and monomer composition.
• Novel instabilities and modes, such as "zig-zag" and potential bistability, expand the understanding of propagating front phenomena.
• The study provides insights into controlling frontal polymerization for advanced material applications.