@article{zhang_pai_turicek_snyder_patrick_soghrati_2024, title={An integrated microstructure reconstruction and meshing framework for finite element modeling of woven fiber-composites}, volume={422}, ISSN={["1879-2138"]}, DOI={10.1016/j.cma.2024.116797}, abstractNote={Critical to finite element (FE) analysis of fiber-reinforced composites is accurately reproducing microstructural features via high-quality meshes such that the material heterogeneity and anisotropy are properly captured. Here we present an integrated computational framework for generating realistic FE models of woven composites with high fiber volume fractions (>50%). This framework relies on a virtual microstructure reconstruction algorithm that first generates a geometric model of loosely-woven yarns (i.e., bundles of fibers), followed by performing an FE compaction simulation to create the final textile composite microstructure. A non-iterative meshing algorithm, i.e., conforming to interface structured adaptive mesh refinement (CISAMR), has been adapted to automatically transform synthesized microstructures into conforming FE meshes. CISAMR can handle challenging geometrical features such as thin resin interstices and yarn interpenetrations (an artifact of the FE compaction) without the need to reprocess the digital geometry before mesh generation. We show that the homogenized elastic moduli obtained from FE simulations of an 8-harness satin woven composite laminate agree well with experimental measurements (within 3%), thereby validating the accuracy of the framework. We also present several other mechanical analysis examples, including a nonlinear damage simulation, that further demonstrate the ability of this framework to construct high-fidelity FE models of intricate woven composites with varying 2D and 3D woven architectures.}, journal={COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING}, author={Zhang, Pengfei and Pai, Salil and Turicek, Jack S. and Snyder, Alexander D. and Patrick, Jason F. and Soghrati, Soheil}, year={2024}, month={Mar} }
 @article{devi_kumar_nakshatrala_patrick_2023, title={A methodology for measuring heat transfer coefficient and self-similarity of thermal regulation in microvascular material systems}, volume={217}, ISSN={["1879-2189"]}, DOI={10.1016/j.ijheatmasstransfer.2023.124614}, abstractNote={Fluid transport through microvascular networks—a hallmark for homeostasis in living systems—has transcended to engineered materials, primarily made possible because of modern manufacturing advancements. Vascular-enabled multifunctionality, including thermal regulation and self-healing, holds great potential for extending the lifetime of structural materials and expanding the operational envelope. Prior studies on vascular-based active cooling use a “combined” heat transfer coefficient (HTC): a single parameter lumps convection and radiation effects. Although the resulting mathematical models are linear—an attractive feature for computational modeling, the combined coefficient approach may not be accurate or even applicable if the operating temperature is unknown, which is the case with many thermal regulation applications (e.g., space probes). In this paper, we illustrate the remarked limitations of the lumped approach and advocate the need to use a decoupled HTC by splitting convective and radiative heat transfer modes. We show the broad applicability of the proposed method by applying it to three material systems: glass and carbon fiber-reinforced polymer composites and an additive manufactured metal. We show, using numerical simulations, the differences in the predictions from the decoupled approach with that of the combined HTC; these differences are prominent at higher heat fluxes. Also, the decoupling has enabled us to establish a scaling law that allows transferring of solutions fields across material systems, strengthening further the validity and utility of our approach. This work's significance is two-fold. First, the research is fundamental, providing accurate measurement protocols for critical model parameters. Second, this work facilitates the development of mathematical models for vascular-based thermal regulation that are predictive even for hostile environments (which are often difficult to realize in laboratories), such as outer space.}, journal={INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER}, author={Devi, Urmi and Kumar, Sandeep R. and Nakshatrala, Kalyana B. and Patrick, Jason F.}, year={2023}, month={Dec} }
 @article{nakshatrala_adhikari_kumar_patrick_2023, title={Configuration-independent thermal invariants under flow reversal in thin vascular systems}, volume={2}, ISSN={["2752-6542"]}, DOI={10.1093/pnasnexus/pgad266}, abstractNote={Abstract Modulating temperature fields is indispensable for advancing modern technologies: space probes, electronic packing, and implantable medical devices, to name a few. Bio-inspired thermal regulation achieved via fluid flow within a network of embedded vesicles is notably desirable for slender synthetic material systems. This far-reaching study—availing theory, numerics, and experiments—reveals a counter-intuitive yet fundamental property of vascular-based fluid-flow-engendered thermal regulation. For such thin systems, the mean surface temperature and the outlet temperature—consequently, the heat extracted by the flowing fluid (coolant)—are invariant under flow reversal (i.e. swapping the inlet and outlet). Despite markedly different temperature fields under flow reversal, our newfound invariance—a discovery—holds for anisotropic thermal conductivity, any inlet and ambient temperatures, transient and steady-state responses, irregular domains, and arbitrary internal vascular topologies, including those with branching. The reported configuration-independent result benefits thermal regulation designers. For instance, the flexibility in the coolant’s inlet location eases coordination challenges between electronics and various delivery systems in microfluidic devices without compromising performance (e.g. soft implantable coolers for pain management). Last but not least, the invariance offers an innovative way to verify computer codes, especially when analytical solutions are unavailable for intricate domain and vascular configurations.}, number={8}, journal={PNAS NEXUS}, author={Nakshatrala, Kalyana B. and Adhikari, Kripa and Kumar, Sandeep Rajendra and Patrick, Jason F.}, year={2023}, month={Aug} }
 @article{hia_snyder_turicek_blanc_patrick_therriault_2023, title={Electrically conductive and 3D-printable copolymer/MWCNT nanocomposites for strain sensing}, volume={232}, ISSN={["1879-1050"]}, DOI={10.1016/j.compscitech.2022.109850}, abstractNote={Structural health monitoring (SHM) of safety-critical composite components is essential to ensure mechanical stasis and detect local damage before it can produce global failure. SHM technologies must also adapt to ever-evolving materials and geometries, but traditional piezoresistive strain sensors lack the ability for end-user customization and modifications throughout service-life. Additive manufacturing via fused filament fabrication (FFF) provides a practical pathway to overcome such sensor shortcomings. However, the electrical conductivity of conventional polymer feedstock is not sufficient for accurate strain measurements without compromise to melt viscosity and thus printability. Here we report the development of a new 3D-printable and electrically responsive nanocomposite by melt-mixing poly(ethylene-co-methacrylic acid) (EMAA) with multi-walled carbon nanotubes (MWCNT). Bulk electrical conductivity of 43.9 S m−1 is achieved at only 5 wt% loading – higher than comparable materials – where the nano-dispersion heterogeneity of MWCNT in EMAA is linked to the favorable conductivity while retaining molten flowability. FFF is employed to print thin (150μm) serpentine strain sensors onto the surface of a glass fiber-reinforced polymer composite, which exhibit strong adhesion and accurate piezoresistive sensing under cyclic flexural loading. Twenty consecutive cycles with converged sensor readings (i.e., < 1% variation in measured resistance) demonstrates reliable performance across a relevant service strain range (0.4 – 0.8 %) for such fiber-composites. This rapid fabrication and transferable sensing strategy, suitable for new and existing structures, thus provides a crosscutting SHM solution.}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Hia, Iee Lee and Snyder, Alexander D. and Turicek, Jack S. and Blanc, Fernanda and Patrick, Jason F. and Therriault, Daniel}, year={2023}, month={Feb} }
 @article{jia_yang_xu_snyder_patrick_kumar_zhang_xu_2023, title={Polymer-derived SiOC reinforced with core-shell nanophase structure of ZrB2/ZrO2 for excellent and stable high-temperature microwave absorption (up to 900 degrees C)}, volume={13}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-023-27541-3}, abstractNote={Microwave absorbing materials for high-temperature harsh environments are highly desirable for aerodynamically heated parts and engine combustion induced hot spots of aircrafts. This study reports ceramic composites with excellent and stable high-temperature microwave absorption in air, which are made of polymer-derived SiOC reinforced with core-shell nanophase structure of ZrB2/ZrO2. The fabricated ceramic composites have a crystallized t-ZrO2 interface between ZrB2 and SiOC domains. The ceramic composites exhibit stable dielectric properties, which are relatively insensitive to temperature change from room temperature to 900 °C. The return loss exceeds - 10 dB, especially between 28 and 40 GHz, at the elevated temperatures. The stable high-temperature electromagnetic (EM) absorption properties are attributed to the stable dielectric and electrical properties induced by the core-shell nanophase structure of ZrB2/ZrO2. Crystallized t-ZrO2 serve as nanoscale dielectric interfaces between ZrB2 and SiOC, which are favorable for EM wave introduction for enhancing polarization loss and absorption. Existence of t-ZrO2 interface also changes the temperature-dependent DC conductivity of ZrB2/SiOC ceramic composites when compared to that of ZrB2 and SiOC alone. Experimental results from thermomechanical, jet flow, thermal shock, and water vapor tests demonstrate that the developed ceramic composites have high stability in harsh environments, and can be used as high-temperature wide-band microwave absorbing structural materials.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Jia, Yujun and Yang, Ni and Xu, Shaofan and Snyder, Alexander D. D. and Patrick, Jason F. F. and Kumar, Rajan and Zhang, Dajie and Xu, Chengying}, year={2023}, month={Jan} }
 @article{turicek_snyder_nakshatrala_patrick_2023, title={Topological effects of 3D-printed copolymer interlayers on toughening and in situ self-healing in laminated fiber-composites}, volume={240}, ISSN={["1879-1050"]}, DOI={10.1016/j.compscitech.2023.110073}, abstractNote={Interlaminar delamination in fiber-reinforced composites limits structural capacity and service life. Delaminations, which occur subsurface and can lead to catastrophic failures, are hard to detect and repair. Contrasting traditional mitigation strategies (e.g., inspection, over-design), proactive toughening and responsive self-healing of damaged interfaces offer practical, cost-effective solutions. Our recently developed strategy to address interlaminar damage—3D-printed thermoplastic interlayers and structurally integrated heaters—has been shown to achieve composite toughening and in situ self-healing via thermal remending, abetting repeated repair and improved delamination resistance. Here, we leverage this latest thermal remending strategy to investigate the effects of 3D-printed pattern topology on damage resistance and self-healing response. The chief attributes are: (i) realizing up to 450% increase in mode-I fracture resistance, (ii) restoring up to 100% of the increased fracture resistance for ten consecutive healing cycles, and (iii) achieving in situ self-healing below the thermoset-matrix glass transition temperature, thereby preserving structural integrity during repair. The proposed damage mitigation strategy fosters structural reliability, reduces failure risk, and increases service lifetime—three essential attributes in meeting the multifaceted demands of modern composite infrastructure.}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Turicek, Jack S. and Snyder, Alexander D. and Nakshatrala, Kalyana B. and Patrick, Jason F.}, year={2023}, month={Jul} }
 @article{snyder_phillips_turicek_diesendruck_nakshatrala_patrick_2022, title={Prolonged in situ self-healing in structural composites via thermo-reversible entanglement}, volume={13}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-022-33936-z}, abstractNote={Natural processes continuously degrade a material's performance throughout its life cycle. An emerging class of synthetic self-healing polymers and composites possess property-retaining functions with the promise of longer lifetimes. But sustained in-service repair of structural fiber-reinforced composites remains unfulfilled due to material heterogeneity and thermodynamic barriers in commonly cross-linked polymer-matrix constituents. Overcoming these inherent challenges for mechanical self-recovery is vital to extend in-service operation and attain widespread adoption of such bioinspired structural materials. Here we transcend existing obstacles and report a fiber-composite capable of minute-scale and prolonged in situ healing - 100 cycles: an order of magnitude higher than prior studies. By 3D printing a mendable thermoplastic onto woven glass/carbon fiber reinforcement and co-laminating with electrically resistive heater interlayers, we achieve in situ thermal remending of internal delamination via dynamic bond re-association. Full fracture recovery occurs below the glass-transition temperature of the thermoset epoxy-matrix composite, thus preserving stiffness during and after repair. A discovery of chemically driven improvement in thermal remending of glass- over carbon-fiber composites is also revealed. The marked lifetime extension offered by this self-healing strategy mitigates costly maintenance, facilitates repair of difficult-to-access structures (e.g., wind-turbine blades), and reduces part replacement, thereby benefiting economy and environment.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Snyder, Alexander D. and Phillips, Zachary J. and Turicek, Jack S. and Diesendruck, Charles E. and Nakshatrala, Kalyana B. and Patrick, Jason F.}, year={2022}, month={Oct} }
 @article{devi_pejman_phillips_zhang_soghrati_nakshatrala_najafi_schab_patrick_2021, title={A Microvascular-Based Multifunctional and Reconfigurable Metamaterial}, ISSN={["2365-709X"]}, DOI={10.1002/admt.202100433}, abstractNote={Nearly all‐natural and synthetic composites derive their characteristic attributes from a hierarchical makeup. Engineered metamaterials exhibit properties not existing in natural composites by precise patterning, often periodically on size scales smaller than the wavelength of the phenomenon they influence. Lightweight fiber‐reinforced polymer composites, comprising stiff/strong fibers embedded within a continuous matrix, offer a superior structural platform for micro‐architectured metamaterials. The emergence of microvascular fiber‐composites, originally conceived for bioinspired self‐healing via microchannels filled with functional fluids, provides a unique pathway for dynamic reconfigurable behavior. Demonstrated here is the new ability to modulate both electromagnetic and thermal responses within a single structural composite by fluid substitution within a serpentine vasculature. Liquid metal infiltration of varying density micro‐channels alters polarized radio‐frequency wave reflection, while water circulation through the same vasculature enables active‐cooling. This latest approach to control bulk property plurality by widespread vascularization exhibits minimal impact on structural performance. Detailed experimental/computational studies, presented in this paper, unravel the effects of micro‐vascular topology on macro‐mechanical behavior. The results, spanning multiple physics, provide a new benchmark for future design optimization and real‐world application of multifunctional and adaptive microvascular composite metamaterials.}, journal={ADVANCED MATERIALS TECHNOLOGIES}, author={Devi, Urmi and Pejman, Reza and Phillips, Zachary J. and Zhang, Pengfei and Soghrati, Soheil and Nakshatrala, Kalyana B. and Najafi, Ahmad R. and Schab, Kurt R. and Patrick, Jason F.}, year={2021}, month={Aug} }
 @article{ma_bharambe_persson_bachmann_joshipura_kim_oh_patrick_adams_dickey_2021, title={Metallophobic Coatings to Enable Shape Reconfigurable Liquid Metal Inside 3D Printed Plastics}, volume={13}, ISSN={["1944-8252"]}, url={https://doi.org/10.1021/acsami.0c17283}, DOI={10.1021/acsami.0c17283}, abstractNote={Liquid metals adhere to most surfaces despite their high surface tension due to the presence of a native gallium oxide layer. The ability to change the shape of functional fluids within a three-dimensional (3D) printed part with respect to time is a type of four-dimensional printing, yet surface adhesion limits the ability to pump liquid metals in and out of cavities and channels without leaving residue. Rough surfaces prevent adhesion, but most methods to roughen surfaces are difficult or impossible to apply on the interior of parts. Here, we show that silica particles suspended in an appropriate solvent can be injected inside cavities to coat the walls. This technique creates a transparent, nanoscopically rough (10-100 nm scale) coating that prevents adhesion of liquid metals on various 3D printed plastics and commercial polymers. Liquid metals roll and even bounce off treated surfaces (the latter occurs even when dropped from heights as high as 70 cm). Moreover, the coating can be removed locally by laser ablation to create selective wetting regions for metal patterning on the exterior of plastics. To demonstrate the utility of the coating, liquid metals were dynamically actuated inside a 3D printed channel or chamber without pinning the oxide, thereby demonstrating electrical circuits that can be reconfigured repeatably.}, number={11}, journal={ACS APPLIED MATERIALS & INTERFACES}, publisher={American Chemical Society (ACS)}, author={Ma, Jinwoo and Bharambe, Vivek T. and Persson, Karl A. and Bachmann, Adam L. and Joshipura, Ishan D. and Kim, Jongbeom and Oh, Kyu Hwan and Patrick, Jason F. and Adams, Jacob J. and Dickey, Michael D.}, year={2021}, month={Mar}, pages={12709–12718} }
 @article{pejman_aboubakr_martin_devi_tan_patrick_najafi_2019, title={Gradient-based hybrid topology/shape optimization of bioinspired microvascular composites}, volume={144}, ISSN={["1879-2189"]}, DOI={10.1016/j.ijheatmasstransfer.2019.118606}, abstractNote={Construction of bioinspired vasculature in synthetic materials enables multi-functional performance via mass transport through internal fluidic networks. However, exact reproduction of intricate, natural microvascular architectures is nearly impossible and thus there is a need to create practical, manufacturable designs guided by multi-physics principles. Here we present a Hybrid Topology/Shape (HyTopS) optimization scheme for microvascular materials using the Interface-enriched Generalized Finite Element Method (IGFEM). This new approach, which can simultaneously perform topological changes as well as shape optimization of microvascular materials, is demonstrated in the context of thermal regulation. In the current study, we present a new feature that enables the optimizer to augment network topology by creating/removing microchannels during the shape optimization process. This task has been accomplished by introducing a new set of design parameters, which act analogous to the penalization factor in the Solid Isotropic Material with Penalization (SIMP) method. The analytical sensitivity for the HyTopS optimization scheme has been derived and the sensitivity accuracy is verified against the finite difference method. We impose a set of geometrical constraints to account for manufacturing limitations and produce a design which is suitable for large-scale production without the need to perform post-processing on the obtained optimum. The method is validated by active-cooling experiments on vascularized carbon-fiber composites. Finally, we compare various application examples to demonstrate the advantages of the newly introduced HyTopS optimization scheme over solely shape optimization for microvascular materials.}, journal={INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER}, author={Pejman, Reza and Aboubakr, Sherif H. and Martin, William H. and Devi, Urmi and Tan, Marcus Hwai Yik and Patrick, Jason F. and Najafi, Ahmad R.}, year={2019}, month={Dec} }
 @article{hart_lankford_freund_patrick_krull_wetzel_sottos_white_2017, title={Repeated healing of delamination damage in vascular composites by pressurized delivery of reactive agents}, volume={151}, ISSN={0266-3538}, url={http://dx.doi.org/10.1016/J.COMPSCITECH.2017.07.027}, DOI={10.1016/J.COMPSCITECH.2017.07.027}, abstractNote={Recurrent self-healing of fracture damage in fiber-reinforced composites was accomplished by incorporating internal vascular networks for repeated delivery of reactive liquid components to an internal delamination. Double cantilever beam specimens containing embedded microvascular channels were repeatedly fractured and healed by pumping individually sequestered epoxy and amine based healing agents to the fracture plane. The effect of various pumping parameters and component delivery ratios on in situ mixing of the healing agents and the resulting healing efficiency is reported. Confocal Raman spectroscopy was used to quantify the extent of mixing of healing agents within the fracture plane. Using an optimized healing agent delivery scheme, ten cycles of fracture and healing were achieved with, on average, 55% and as high as 95%, recovery of the virgin critical strain energy release rate.}, journal={Composites Science and Technology}, publisher={Elsevier BV}, author={Hart, Kevin R. and Lankford, Seth M. and Freund, Isaac A. and Patrick, Jason F. and Krull, Brett. P. and Wetzel, Eric D. and Sottos, Nancy R. and White, Scott R.}, year={2017}, month={Oct}, pages={1–9} }
 @article{patrick_krull_garg_mangun_moore_sottos_white_2017, title={Robust sacrificial polymer templates for 3D interconnected microvasculature in fiber-reinforced composites}, volume={100}, ISSN={1359-835X}, url={http://dx.doi.org/10.1016/j.compositesa.2017.05.022}, DOI={10.1016/j.compositesa.2017.05.022}, abstractNote={A promising pathway for multifunctionality in fiber-composites is to mimic biological vasculature that enables living organisms with concerted homeostatic functions. In this paper, newfound material and processing advancements in vaporization of sacrificial components (VaSC), a technique for creating inverse replica architectures via thermal depolymerization of a sacrificial template, are established for enhanced vascular composites manufacturing. Sacrificial poly(lactic acid) with improved distribution of catalytic micro-particles is extruded into fibers for automated weaving and filament feedstock for 3-D printing. Fiber drawing after extrusion improves mechanical robustness for high-fidelity, composite preform weaving. Joining one-dimensional (1D) interwoven fibers with printed sacrificial (2D) templates affords three-dimensional (3D) interconnected networks in a fiber-composite laminate that inherits damage-tolerant features found in natural vasculatures. In addition to providing a conduit for enhanced functionality, the sacrificial templating techniques are compatible with current composites manufacturing processes, materials, and equipment.}, journal={Composites Part A: Applied Science and Manufacturing}, publisher={Elsevier BV}, author={Patrick, J.F. and Krull, B.P. and Garg, M. and Mangun, C.L. and Moore, J.S. and Sottos, N.R. and White, S.R.}, year={2017}, month={Sep}, pages={361–370} }
 @article{krull_patrick_hart_white_sottos_2016, title={Automatic Optical Crack Tracking for Double Cantilever Beam Specimens}, volume={40}, ISSN={["1747-1567"]}, DOI={10.1007/s40799-016-0094-9}, number={3}, journal={EXPERIMENTAL TECHNIQUES}, author={Krull, B. and Patrick, J. and Hart, K. and White, S. and Sottos, N.}, year={2016}, month={Jun}, pages={937–945} }
 @misc{patrick_robb_sottos_moore_white_2016, title={Polymers with autonomous life-cycle control}, volume={540}, ISSN={["1476-4687"]}, DOI={10.1038/nature21002}, number={7633}, journal={NATURE}, author={Patrick, Jason F. and Robb, Maxwell J. and Sottos, Nancy R. and Moore, Jeffrey S. and White, Scott R.}, year={2016}, month={Dec}, pages={363–370} }
 @article{krull_gergely_cruz_fedonina_patrick_white_sottos_2016, title={Strategies for Volumetric Recovery of Large Scale Damage in Polymers}, volume={26}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.201600486}, abstractNote={The maximum volume that can be restored after catastrophic damage in a newly developed regenerative polymer system is explored for various mixing, surface wetting, specimen configuration, and microvascular delivery conditions. A two‐stage healing agent is implemented to overcome limitations imposed by surface tension and gravity on liquid retention within a damage volume. The healing agent is formulated as a two‐part system in which the two reagent solutions are delivered to a through‐thickness, cylindrical defect geometry by parallel microvascular channels in thin epoxy sheets. Mixing occurs as the solutions enter the damage region, inducing gelation to initiate an accretive deposition process that enables large damage volume regeneration. The progression of the damage recovery process is tracked using optical and fluorescent imaging, and the mixing efficiency is analyzed. Complete recovery of gaps spanning 11.2 mm in diameter (98 mm2) is achieved under optimal conditions.}, number={25}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Krull, Brett P. and Gergely, Ryan C. R. and Cruz, Windy A. Santa and Fedonina, Yelizaveta I. and Patrick, Jason F. and White, Scott R. and Sottos, Nancy R.}, year={2016}, month={Jul}, pages={4561–4569} }
 @article{gergely_pety_krull_patrick_doan_coppola_thakre_sottos_moore_white_2015, title={Biopolymers: Multidimensional Vascularized Polymers using Degradable Sacrificial Templates (Adv. Funct. Mater. 7/2015)}, volume={25}, ISSN={1616-301X}, url={http://dx.doi.org/10.1002/ADFM.201570048}, DOI={10.1002/ADFM.201570048}, abstractNote={S. R. White and co-workers develop sacrificial templates of 0D to 3D used to create vascular and porous architectures in polymers on page 1043. Embedded sacrificial templates are removed using a thermal treatment process, VaSC, leaving behind an inverse replica. This reconstruction of microCT imaging shows 3D channel architecture created using a 3D printed sacrificial template and the pressure distribution of fluid flow.}, number={7}, journal={Advanced Functional Materials}, publisher={Wiley}, author={Gergely, Ryan C. R. and Pety, Stephen J. and Krull, Brett P. and Patrick, Jason F. and Doan, Thu Q. and Coppola, Anthony M. and Thakre, Piyush R. and Sottos, Nancy R. and Moore, Jeffrey S. and White, Scott R.}, year={2015}, month={Feb}, pages={1042–1042} }
 @article{gergely_pety_krull_patrick_doan_coppola_thakre_sottos_moore_white_2015, title={Multidimensional Vascularized Polymers using Degradable Sacrificial Templates}, volume={25}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.201403670}, abstractNote={Complex multidimensional vascular polymers are created, enabled by sacrificial template materials of 0D to 3D. Sacrificial material consisting of the commodity biopolymer poly(lactic acid) is treated with a tin catalyst to accelerate thermal depolymerization, and formed into sacrificial templates across multiple dimensions and spanning several orders of magnitude in scale: spheres (0D), fibers (1D), sheets (2D), and 3D printed. Templates are embedded in a thermosetting polymer and removed using a thermal treatment process, vaporization of sacrificial components (VaSC), leaving behind an inverse replica. The effectiveness of VaSC is verified both ex situ and in situ, and the resulting structures are validated via flow 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.}, number={7}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Gergely, Ryan C. R. and Pety, Stephen J. and Krull, Brett P. and Patrick, Jason F. and Doan, Thu Q. and Coppola, Anthony M. and Thakre, Piyush R. and Sottos, Nancy R. and Moore, Jeffrey S. and White, Scott R.}, year={2015}, month={Feb}, pages={1043–1052} }
 @article{patrick_hart_krull_diesendruck_moore_white_sottos_2014, title={Continuous Self-Healing Life Cycle in Vascularized Structural Composites}, volume={26}, ISSN={["1521-4095"]}, DOI={10.1002/adma.201400248}, abstractNote={J. F. Patrick Civil and Environmental Engineering Department Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign Urbana , IL 61801 , USA K. R. Hart, Prof. S. R. White Aerospace Engineering Department Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign Urbana , IL 61801 , USA E-mail: swhite@illinois.edu Dr. C. E. Diesendruck, Prof. J. S. Moore Chemistry Department Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign Urbana , IL 61801 , USA B. P. Krull, Prof. N. R. Sottos Materials Science and Engineering Department Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign Urbana , IL 61801 , USA E-mail: n-sottos@illinois.edu}, number={25}, journal={ADVANCED MATERIALS}, author={Patrick, Jason F. and Hart, Kevin R. and Krull, Brett P. and Diesendruck, Charles E. and Moore, Jeffrey S. and White, Scott R. and Sottos, Nancy R.}, year={2014}, month={Jul}, pages={4302–4308} }
 @article{patrick_hart_krull_diesendruck_moore_white_sottos_2014, title={Self-Healing: Continuous Self-Healing Life Cycle in Vascularized Structural Composites (Adv. Mater. 25/2014)}, volume={26}, ISSN={0935-9648}, url={http://dx.doi.org/10.1002/ADMA.201470166}, DOI={10.1002/ADMA.201470166}, abstractNote={By incorporating three-dimensional microvascular networks within a woven glass fiber-reinforced polymer composite N. R. Sottos, S. R. White, and co-workers demonstrate on page 4302 the full recovery (>100%) of mode-I fracture resistance after multiple damage events. This optical image of a fracture plane reveals efficient delivery, mixing and polymerization of the fluorescently dyed, two-part reactive healing chemistry.}, number={25}, journal={Advanced Materials}, publisher={Wiley}, author={Patrick, Jason F. and Hart, Kevin R. and Krull, Brett P. and Diesendruck, Charles E. and Moore, Jeffrey S. and White, Scott R. and Sottos, Nancy R.}, year={2014}, month={Jul}, pages={4189–4189} }
 @article{king_patrick_sottos_white_huff_bernhard_2013, title={Microfluidically switched frequency-reconfigurable slot antennas}, volume={12}, DOI={10.1109/lawp.2013.2270940}, abstractNote={This letter proposes a concept for frequency-reconfigurable slot antennas enabled by pressure-driven capacitive microfluidic switches. The switches are operated by pneumatically displacing a plug of eutectic gallium indium alloy (EGaIn) within an air-filled microchannel that traverses the slot orthogonally. Frequency reconfigurability is achieved by altering the displacement of conductive fluid within the channel, which reactively loads the slot. A transmission-line model is developed to capture the physical behavior of the fluid channel, and measurements are provided that show good agreement with the behavior of the model.}, journal={IEEE Antennas and Wireless Propagation Letters}, author={King, A. J. and Patrick, J. F. and Sottos, N. R. and White, S. R. and Huff, G. H. and Bernhard, J. T.}, year={2013}, pages={828–831} }
 @article{dong_esser-kahn_thakre_patrick_sottos_white_moore_2012, title={Chemical Treatment of Poly(lactic acid) Fibers to Enhance the Rate of Thermal Depolymerization}, volume={4}, ISSN={["1944-8252"]}, DOI={10.1021/am2010042}, abstractNote={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% H(2)O 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.}, number={2}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Dong, Hefei and Esser-Kahn, Aaron P. and Thakre, Piyush R. and Patrick, Jason F. and Sottos, Nancy R. and White, Scott R. and Moore, Jeffrey S.}, year={2012}, month={Feb}, pages={503–509} }
 @article{patrick_sottos_white_2012, title={Microvascular based self-healing polymeric foam}, volume={53}, ISSN={["1873-2291"]}, DOI={10.1016/j.polymer.2012.07.021}, abstractNote={A self-healing microvascular polymeric foam has been developed to improve the resilience of rigid foam core materials for sandwich structures. We investigated the healing of brittle polyisocyanurate (PIR) foam after mode-I crack separation in a 3-point single edge notch bend (SENB) specimen. A two-part healing chemistry based on a commercially available polyurethane (PUR) foam formulation is employed to rebond the interface. Both components are initially sequestered in separate channels in a vascularized SENB geometry. Upon loading and subsequent crack propagation through the network, the healing agents are released and polymerize on contact to create new foam material in the crack plane. An attractive feature of this system is the volumetric expansion of the healing chemistry, demonstrating the ability to repair macro-scale damage. The foaming reaction occurs on the order of minutes at room temperature, enabling rapid in-situ healing. Furthermore, by using a vascular delivery technique, multiple damage–recovery cycles are achieved at consistently high healing efficiencies. Through repeated mechanical testing, we have demonstrated over 100% recovery in fracture toughness for this new class of bioinspired, self-healing cellular materials.}, number={19}, journal={POLYMER}, author={Patrick, J. F. and Sottos, N. R. and White, S. R.}, year={2012}, month={Aug}, pages={4231–4240} }
 @article{esser-kahn_thakre_dong_patrick_vlasko-vlasov_sottos_moore_white_2011, title={Hybrid Materials: Three-Dimensional Microvascular Fiber-Reinforced Composites (Adv. Mater. 32/2011)}, volume={23}, ISSN={0935-9648}, url={http://dx.doi.org/10.1002/adma.201190127}, DOI={10.1002/adma.201190127}, abstractNote={Four undulating microchannels of a 3D microvascular network are integrated into a structural composite, as revealed by microCT imaging. Jeffrey S. Moore, Scott R. White, and co-workers report that fabrication is accomplished by weaving sacrificial polylactide fibers into the preform prior to conventional composite manufacturing. A post-curing process depolymerizes the polylactide, leaving behind high-fidelity, inverse replicas of the original sacrificial fiber.}, number={32}, journal={Advanced Materials}, publisher={Wiley}, author={Esser-Kahn, Aaron P. and Thakre, Piyush R. and Dong, Hefei and Patrick, Jason F. and Vlasko-Vlasov, Vitalii K. and Sottos, Nancy R. and Moore, Jeffrey S. and White, Scott R.}, year={2011}, month={Aug}, pages={3653–3653} }
 @article{esser-kahn_thakre_dong_patrick_vlasko-vlasov_sottos_moore_white_2011, title={Three-Dimensional Microvascular Fiber-Reinforced Composites}, volume={23}, ISSN={["0935-9648"]}, DOI={10.1002/adma.201100933}, abstractNote={and materials or lack of scalability and vascular complexity of the fabrication approach. Here we show that the introduction of sacrificial fibers into woven preforms enables the seamless fabrication of 3D microvascular composites that are both strong and multifunctional. Underpinning the method is the efficient thermal depolymerization of catalyst-impregnated polylactide (PLA) fibers with simultaneous evaporative removal of the resulting lactide monomer. The hollow channels produced are high-fidelity inverse replicas of the original fiber’s diameter and trajectory. The method has yielded microvascular fiber-reinforced composites with channels over one meter in length that can be subsequently filled with a variety of liquids including aqueous solutions, organic solvents, and liquid metals. By circulating fluids with unique physical properties, we demonstrate the ability to create a new generation of biphasic pluripotent composite materials in which the solid phase provides strength and form while the liquid phase provides interchangeable functionality. Microvascular composite fabrication begins with the mechanized weaving of sacrifi cial fi bers into 3D woven glass}, number={32}, journal={ADVANCED MATERIALS}, author={Esser-Kahn, Aaron P. and Thakre, Piyush R. and Dong, Hefei and Patrick, Jason F. and Vlasko-Vlasov, Vitalii K. and Sottos, Nancy R. and Moore, Jeffrey S. and White, Scott R.}, year={2011}, month={Aug}, pages={3654-+} }