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When heated, poly(lactic acid) (PLA) fibers depolymerize in a controlled manner, making them potentially useful as sacrificial fibers for microchannel fabrication. Catalysts that increase PLA depolymerization rates are explored and methods to incorporate them into commercially available PLA fibers by a solvent mixture impregnating technique are tested. In the present study, the most active catalysts are identified that are capable of lowering the depolymerization temperature of modified PLA fibers by ca. 100 °C as compared to unmodified ones. Lower depolymerization temperatures allow PLA fibers to be removed from a fully cured epoxy thermoset resin without causing significant thermal damage to the epoxy. For 500 μm diameter PLA fibers, the optimized treatment involves soaking the fibers for 24 h in a solvent mixture containing 60% trifluoroethanol (TFE) and 40% H2O dispersed with 10 wt % tin(II) oxalate and subsequent air-drying of the fibers. PLA fibers treated with this procedure are completely removed when heated to 180 °C in vacuo for 20 h. The time evolution of catalytic depolymerization of PLA fiber is investigated by gel permeation chromatography (GPC). Channels fabricated by vaporization of sacrificial components (VaSC) are subsequently characterized by scanning electron microscopy (SEM) and X-ray microtomography (Micro CT) to show the presence of residual catalysts.

1043wileyonlinelibrary.com and autonomous materials. [22][23][24] Porous materials not only mediate transport of fl uids in fi ltration, [ 25 ] but also regulate ion exchange in battery electrodes [ 26 ] and separator fi lms, [ 27 ] facilitate new tissue growth in bioscaffolds, [28][29][30][31] and increase strength-to-weight ratio in structural solids. [ 32 ] No fabrication technique has emerged with the fl exibility to control size and dimensionality across all of these applications.Esser-Kahn et al. [ 23 ] recently introduced the vaporization of sacrifi cial components (VaSC) technique. In their work, 1D poly(lactic acid) (PLA) fi bers are treated with tin(II) oxalate (SnOx) catalyst to undergo thermal depolymerization and vaporization at ≈200 °C. After embedding "sacrifi cial" PLA in a thermoset composite and subsequent thermal treatment, the fi bers vaporized, forming vasculature that is their inverse replica. By introducing various functional fl uids into the microvasculature, desirable properties were imparted on the composite, such as thermal regulation, magnetic or electrical modulation, and in situ reaction of chemical species. [ 23 ] In this work, we extend the application of VaSC by introducing sacrifi cial templates across all levels of spatial dimensionality and spanning several orders of magnitude in size, enabling a wide range of vascular and porous architectures.Complex multidimensional vascular polymers are created, enabled by sacrificial template materials of 0D to 3D. Sacrifi cial material consisting of the commodity biopolymer poly(lactic acid) is treated with a tin catalyst to accelerate thermal depolymerization, and formed into sacrifi cial templates across multiple dimensions and spanning several orders of magnitude in scale: spheres (0D), fi bers (1D), sheets (2D), and 3D printed. Templates are embedded in a thermosetting polymer and removed using a thermal treatment process, vaporization of sacrifi cial components (VaSC), leaving behind an inverse replica. The effectiveness of VaSC is verifi ed both ex situ and in situ, and the resulting structures are validated via fl ow rate testing. The VaSC platform is expanded to create vascular and porous architectures across a wide range of size and geometry, allowing engineering applications to take advantage of vascular designs optimized by biology.