Bioinspired microvascular networks for multifunctional composites

In biological systems, fluid transport through internal vasculature enables a plurality of metabolic and homeostatic functions including respiration, circulation, thermal regulation, and self-repair. Natural, load-bearing materials such as bone and wood rely on nutrient exchange through a series of complex networks to achieve mechanical stasis via cellular proliferation (growth) and tissue regeneration. While synthetic fiber-reinforced composites (FRC) attain comparable specific strength/stiffness properties to these living hierarchical materials, the ability to sustain structural performance over a wide range of environmental conditions and engineering applications has yet to be accomplished. One promising pathway for accession of multifunctionality in man-made FRC is to mimic successful, evolutionary-derived vascular constructions. Here we show advancements for a recently developed technique [1-3] designated vaporization of sacrificial components (VaSC), where inverse replica microvasculature is created within fiber-composites through thermal depolymerization of a sacrificial precursor. Metal catalyst micro-particles are incorporated into a commodity biopolymer, poly(lactic) acid (PLA), and extruded into printable filament for an additive manufacturing process known as fused deposition modeling (FDM). The sacrificial printing technique is both economical and scalable using commercially available materials, processes, and equipment. By expanding the VaSC procedure beyond one-dimensional (1D) segregated channels, to three-dimensional (3D) interconnected networks closer resembling biological vasculature, the range of dynamic functionalities for fiber-composites is increased. In addition to providing enhanced multifunctional properties, 3D printed networks also possess damage-tolerant features found in natural vasculatures [4].