Poly(urea-urethane) thermosets containing the 1-tert-butylethylurea (TBEU) structure feature a reversible dissociation/association process of their covalent linkages under mild conditions. Unlike conventional thermosets, TBEU-based poly(urea-urethane) thermosets maintain their malleability after curing. Under high temperature (100 °C) and applied pressure (300 kPa), ground TBEU thermoset powder can be remolded to bulk after 20 min.

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.

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