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Nanomaterials must be systematically designed to be technologically viable1,2,3,4,5. Driven by optimizing intermolecular interactions, current designs are too rigid to plug in new chemical functionalities and cannot mitigate condition differences during integration6,7. Despite extensive optimization of building blocks and treatments, accessing nanostructures with the required feature sizes and chemistries is difficult. Programming their growth across the nano-to-macro hierarchy also remains challenging, if not impossible8,9,10,11,12,13. To address these limitations, we should shift to entropy-driven assemblies to gain design flexibility, as seen in high-entropy alloys, and program nanomaterial growth to kinetically match target feature sizes to the mobility of the system during processing14,15,16,17. Here, following a micro-then-nano growth sequence in ternary composite blends composed of block-copolymer-based supramolecules, small molecules and nanoparticles, we successfully fabricate high-performance barrier materials composed of more than 200 stacked nanosheets (125 nm sheet thickness) with a defect density less than 0.056 µm−2 and about 98% efficiency in controlling the defect type. Contrary to common perception, polymer-chain entanglements are advantageous to realize long-range order, accelerate the fabrication process (<30 min) and satisfy specific requirements to advance multilayered film technology3,4,18. This study showcases the feasibility, necessity and unlimited opportunities to transform laboratory nanoscience into nanotechnology through systems engineering of self-assembly.
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This work was funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under contract DE-AC02-05CH11231 (Organic–Inorganic Nanocomposites KC3104). E.V. was supported by the Department of Defense through the National Defense Science and Engineering Graduate (NDSEG) Fellowship Program. J.J. was supported by a National Science Foundation Graduate Research Fellowship under grant no. DGE 1752814. H.D. and X.T. acknowledge support from the Laboratory Directed Research and Development (LDRD) programme under contract no. DE-AC02-05CH11231. Membrane fabrication for VOC and water-permeability testing was supported by the Defense Threat Reduction Agency under contract no. HDTRA1-22-1-0005. Part of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory, the Advanced Photon Source operated by the Argonne National Laboratory, under contract no. DE-AC02-06CH11357, the Advanced Light Source and the Molecular Foundry operated by the Lawrence Berkeley National Laboratory under contract no. DE-AC02-05CH11231. We thank A. Minor for providing access to the nanoindentation measurements. Q.Z. thanks R. Ziegler and D. P. Jensen Jr. for technical assistance.
Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, USA
Emma Vargo, Le Ma, Victoria L. Tovmasyan, Robert O. Ritchie & Ting Xu
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
Emma Vargo, Le Ma, He Li, Junpyo Kwon, Robert O. Ritchie, Yi Liu & Ting Xu
The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
He Li & Yi Liu
X-ray Science Division, Argonne National Laboratory, Lemont, IL, USA
Qingteng Zhang, Ivan Kuzmenko & Jan Ilavsky
Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA, USA
Junpyo Kwon & Robert O. Ritchie
Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA
Katherine M. Evans & Ting Xu
Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
Xiaochen Tang & Hugo Destaillats
Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
Jasmine Jan & Ana C. Arias
Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
Wei-Ren Chen & William Heller
Kavli Energy NanoScience Institute, Berkeley, CA, USA
Ting Xu
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T.X. and E.V. conceived the idea and guided the project. E.V., L.M., K.M.E. and T.X. studied supramolecular phase behaviours. E.V. developed the fabrication process, analysed the growth process and prepared coatings for testing, with assistance from V.L.T. Q.Z. assisted with XPCS data collection and analysis. J.K. and R.O.R. performed mechanical-property measurements. X.T. and H.D. performed VOC barrier testing. H.L. and Y.L. performed dielectric measurements and synthesized small molecules for control studies. W.-R.C. and W.H. performed the USANS studies and assisted with the data analysis. I.K. and J.I. helped collect the USAXS measurements. J.J. and A.C.A. performed electrical calcium conductivity tests of calcium protected by the nanocomposite and control barriers.
Correspondence to Ting Xu.
T.X., E.V. and L.M. have a pending PCT patent application. The remaining authors declare no competing interests.
Nature thanks Darrin Pochan, Du Yeol Ryu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
TEM images of variations on the S2/NP blend formulation. a, S2 supramolecules with 6 vol% 5 nm iron oxide nanoparticles. b, 330-b-125 kDa supramolecules formed using a different hydrogen-bonding small molecule, I-PDP (inset). This is the same blend used for EDS analysis. c, 330-b-125 kDa supramolecules formed using a blend of hydrogen-bonding (PDP) and non-hydrogen-bonding small molecules (DID) at molar ratios of 1 and 0.6, respectively. d–i, S2/NP blends self-assembled on a variety of substrates: a Teflon beaker, a porous Teflon membrane, a polyester film, a silicon wafer (thick and thin films shown) and glass.
Iodine-labelled small molecules are used to show the small-molecule distribution in a S2/NP blend. The structural and chemical information is collected using a high-angle annular dark-field set-up, so the contrast is reversed compared with the other TEM images shown in this work. The brightest pixels are those that scatter most strongly, so the nanoparticle-filled domains are lighter than the organic-only domains. The iodine map shows that I-PDP are distributed throughout all microdomains, despite the enthalpic driving force for them to segregate into the P4VP(PDP) domains. By comparison, the ZrO2 nanoparticles are strictly partitioned into the P4VP(PDP) domains. This imaging technique does not differentiate between hydrogen-bonded and unbonded small molecules, so the P4VP(PDP) domains have an overall higher concentration of small molecules.
a–d, Every SANS curve is fit with a two-part model, with the higher-q part representing the behaviour of individual supramolecules and the lower-q part representing the behaviour of the nanosheet aggregates. e, In the case of the USANS data, a third lower-q part is added to represent the collective behaviour of the nanosheets. Critically, the USANS data are absolutely calibrated, so the magnitude of the scattering intensity can be compared across samples. Compared with the solvent, the supramolecules have a lower scattering length density (SLD) and the nanoparticles have a higher SLD. The 5-vol% S2 solution has markedly higher scattering intensity than the 5-vol% S2/NP solution. This is consistent with isolated nanoparticles distributed throughout the supramolecular aggregates. If the nanoparticles are distributed evenly throughout the supramolecular aggregates, the spatially averaged SLD will be more similar to the surrounding solvent and a lower overall intensity is expected. If the particles were instead packed densely in specific regions of the supramolecular aggregates, the SLD contrast would be greater than in the sample without particles and higher scattering intensity would be seen. Indeed, this is exactly the trend we observe in the 10-vol% S2 and S2/NP solutions. This analysis is discussed further in the Supporting Information.
These panels show g2 data corresponding to the assembly stages i–iv labelled in Fig. 2d–f. The first two g2 plots used the ‘fast dynamics’ set-up and the remaining four use the ‘slow dynamics’ set-up.
We varied the incubation time Δt between the formation of molecular aggregates, indicated by a diffuse scattering ring (q = 0.027 Å−1, full width at half maximum = 0.0058 Å−1) and the formation of cylindrical microdomains (q = 0.026 Å−1, full width at half maximum = 0.0013 Å−1). Δt is defined as tf − ti, in which ti is the time elapsed between the initial solution deposition and the first appearance of molecular aggregates. For two different drying conditions, the first appearance of molecular aggregates (Δt = 0) is shown on the left. For drying condition 1, ti = 23:28 min; for drying condition 2, ti = 49:18 min. As shown below, when Δt < 1 min, the final film is poorly ordered. When Δt = 11 min, the film forms highly ordered, hexagonally packed cylindrical microdomains, seen as sharp, highly ordered diffraction peaks. The results are consistent with the XPCS studies of S2/NP shown in the main text. Thus, long-range order can be obtained by varying Δt for morphologies other than lamellae.
The TEM images were used to calculate defect densities and sheet lengths for thick and thin films. STEM tomography reconstruction was performed for a S2 film. The U-turn defect reconstructions confirmed that these characteristic defects are indeed continuous nanosheets folded at a sharp angle.
Examples of an automated sheet-length analysis and a semi-automated defect-density analysis, performed on the S2 film frozen at 40 vol%. As described in Methods, junction and ends were identified automatically. U-turn defects were labelled manually.
a, When a film is dried, redissolved and then recast, it forms the same lamellar structure as before. b, Nanoindentation results show that S2/NP films are mechanically stable despite the lack of chemical crosslinks between layers. c, Cyclic buckling tests (n = 600) of S2/NP on a PET film show that the film remains intact without any delamination from the substrate. d, Disordered nanocomposites (S2dis/NP) and lamellae without nanoparticles (S2) both had inferior properties, although all tested films had the same thickness and were supported by the same PET film.
a, The WVTR values reported in the main text come from the linear fits on the time series data shown below. b, The dielectric results include Weibull plots of dielectric breakdown strength for S2/NP, S2dis/NP, S2 and S1/NP films. Discharged energy density (c) and charge–discharge efficiency as a function of applied electric field (d) of S2/NP, S2dis/NP, S2 and S1/NP films. Dielectric performance for commercial BOPP is also plotted as a control sample.
Supplementary Sections 1–3: Guinier–Porod model information and fitting approach; defect analysis data; and high-resolution TEM cross-sections of S2/NP and S1/NP thick films.
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Vargo, E., Ma, L., Li, H. et al. Functional composites by programming entropy-driven nanosheet growth. Nature (2023). https://doi.org/10.1038/s41586-023-06660-x
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