@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} }