@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"]}, url={http://dx.doi.org/10.1038/s41467-022-33936-z}, 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}, publisher={Springer Science and Business Media LLC}, author={Snyder, Alexander D. and Phillips, Zachary J. and Turicek, Jack S. and Diesendruck, Charles E. and Nakshatrala, Kalyana B. and Patrick, Jason F.}, editor={Turicek, Jack S.Editor}, 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={Abstract 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} }