Harnessing Surface Tension Driven Flows During Frontal Polymerization for the Fabrication of Functional Materials

Frontal polymerization (FP) has emerged as a rapid, energy-efficient, and scalable manufacturing technique for thermosetting polymers. FP is reliant on the heat generated from an exothermic reaction to propagate a linear heat front, allowing available monomer to be rapidly converted to the resulting polymer. Typically, monomer resin is activated locally by a thermal stimulus which initiates the polymerization process. During polymerization in a free-surface geometry, thermal and concentration gradients arise, which has been shown to initiate surface tension (Marangoni) driven convection. In this work, we utilize the synthetic reaction-diffusion system that arises from the FP of dicyclopentadiene (DCPD) with Grubb’s second-generation catalyst and a phosphite inhibitor. Efforts are focused on the investigation of the dynamics emerging from such a coupling between the exothermic autocatalytic reaction, diffusion, and surface tension driven flows of the propagating reaction front in a horizontal system open to air. Utilizing particle image velocimetry (PIV), we can further determine the parameters that drive the spatio-temporal dynamics and study the evolution of the flow in the horizontal channels. We exploit these surface tension driven flows to fabricate functional polymers with patterned microstructures. Ongoing work seeks to understand how the flow influences the resulting structure and properties of the polymers.