Multiphysics Modeling and Experimental Study of a Concurrent Polymerization and Vascularization Process for Manufacturing Polymer and Polymer Composites with Embedded Microvascular System

Biological materials possess hierarchical vascular networks that mediate heat and mass transport in response to external and internal stimuli, enabling complex living systems to thrive in extreme environments. Inspired by these natural systems, there is an increasing desire to replicate such vascular networks in engineered materials for mass and heat transportation in the field of microfluidics, self-regulating temperature control structure, and microelectronics. Lengthy, multistep fabrication processes involving solvents, external heat, and vacuum hinder large-scale application of vascular networks in structural materials.<br/>Recently, a novel synchronized fabrication process for vascularized thermosets and composites have been proposed. In this process, the exothermic frontal polymerization (FP) of a liquid or gelled dicyclopentadiene (DCPD) resin facilitates coordinated depolymerization of an embedded sacrificial polymer (propylene carbonate) (PPC) template to create hollow structures with high-fidelity interconnected micro channels. The chemical energy released during rapid and self-sustained matrix polymerization eliminates the need for a sustained external heat source and greatly reduces external energy and time consumption for processing. To better understand this process, and probe the working window of this technique, we develop a multiphysics framework to study the impact of boundary condition, chemical composition, and fiber volume fraction on the vascularization process. In this multiphysics system, a coupled thermo-chemical equation system is solved within the open-source Multiphysics Object-Oriented Simulation Environment (MOOSE), relying on its adaptive mesh refinement and time stepping.<br/>In the first part of the presentation, we focus on the so-called linear vascularization, where the direction of the polymerization front is parallel to the sacrificing template. We systematically studied the working window where thorough curing of the matrix as well as full degradation of the sacrificing fiber can be achieved under open-air as well as glass mold conditions. In the second part, we focus on the through-thickness vascularization, where the direction of the polymerization front is through thickness along the thickness direction, hence perpendicular to the sacrificing filament. In this case, we. focus more on studying the impact of carbon fiber and PPC volume fraction of the host composite laminate and investigate the carbon fiber and PPC volume fraction we can achieve using this method. In both cases, the results are compared with experiments and which show reasonable match. Further insights were gained from the computational modeling by exploring relevant parameters associated with the manufacturing process.