Small-molecule self-assembly is an established route for producing high-surface-area nanostructures with readily customizable chemistries and precise molecular organization. However, these structures are fragile, exhibiting molecular exchange, migration and rearrangement—among other dynamic instabilities—and are prone to dissociation upon drying. Here we show a small-molecule platform, the aramid amphiphile, that overcomes these dynamic instabilities by incorporating a Kevlar-inspired domain into the molecular structure. Strong, anisotropic interactions between aramid amphiphiles suppress molecular exchange and elicit spontaneous self-assembly in water to form nanoribbons with lengths of up to 20 micrometres. Individual nanoribbons have a Young’s modulus of 1.7 GPa and tensile strength of 1.9 GPa. We exploit this stability to extend small-molecule self-assembly to hierarchically ordered macroscopic materials outside of solvated environments. Through an aqueous shear alignment process, we organize aramid amphiphile nanoribbons into arbitrarily long, flexible threads that support 200 times their weight when dried. Tensile tests of the dry threads provide a benchmark for Young’s moduli (between ~400 and 600 MPa) and extensibilities (between ~0.6 and 1.1%) that depend on the counterion chemistry. This bottom-up approach to macroscopic materials could benefit solid-state applications historically inaccessible by self-assembled nanomaterials.
The data generated and analysed during this study are available from the corresponding author on reasonable request.
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We thank E. Deiss-Yehiely and C. Settens for their helpful input. We thank R. Allen and L. Hopkins for contributing graphics shown in the figures. We acknowledge J. Tian and S. Kallakuri for contributions to synthesis of early stage AAs that led to the molecular designs incorporated in this report. This material is based upon work supported by the National Science Foundation under grant no. CHE-1945500. This work was supported in part by the Professor Amar G. Bose Research Grant Program, the Abdul Latif Jameel Water and Food Systems Lab, and the MIT Center for Environmental Health Sciences under NIH Center grant P30-ES002109. D.-Y.K. acknowledges the support of the National Research Foundation of Korea’s Basic Science Research Program and Chonbuk National University Fellowship Program. T.C.-T. and W.R.L. acknowledge the support of the National Science Foundation Graduate Research Fellowship Program under grant no. 1122374. T.C.-T. acknowledges the support of the Martin Family Society of Fellows for Sustainability. G.L. acknowledges support from the Université d’Evry-Paris Saclay. This work made use of the MRSEC Shared Experimental Facilities at MIT supported by the National Science Foundation under award number DMR-14-19807 and the MIT Department of Chemistry Instrumentation Facility. X-ray scattering measurements were performed at beamline 12-ID-B of the Advanced Photon Source, a US Department of Energy Office of Science User Facility operated for the US Department of Energy Office of Science by Argonne National Laboratory under contract no. DE-AC02-06CH11357. This work was performed in part at the Harvard University Center for Nanoscale Systems cryo-TEM facility, a member of the National Nanotechnology Coordinated Infrastructure Network, which is supported by the National Science Foundation under award no. 1541959.
The authors declare no competing interests.
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Christoff-Tempesta, T., Cho, Y., Kim, DY. et al. Self-assembly of aramid amphiphiles into ultra-stable nanoribbons and aligned nanoribbon threads. Nat. Nanotechnol. (2021). https://doi.org/10.1038/s41565-020-00840-w
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