Abstract
Bicontinuous microstructures are essential to the function of diverse natural and synthetic systems. Their synthesis has been based on two approaches: arrested phase separation or self-assembly of block copolymers. The former is attractive for its chemical simplicity and the latter, for its thermodynamic robustness. Here we introduce elastic microphase separation (EMPS) as an alternative approach to make bicontinuous microstructures. Conceptually, EMPS balances the molecular-scale forces that drive demixing with large-scale elasticity to encode a thermodynamic length scale. This process features a continuous phase transition, reversible without hysteresis. Practically, EMPS is triggered by simply supersaturating an elastomeric matrix with a liquid, resulting in uniform bicontinuous materials with a well-defined microscopic length scale tuned by the matrix stiffness. The versatility of EMPS is further demonstrated by fabricating bicontinuous materials with superior mechanical properties and controlled anisotropy and microstructural gradients. Overall, EMPS presents a robust alternative for the bulk fabrication of homogeneous bicontinuous materials.
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Data availability
Source data are provided with this paper. Further data supporting the findings of this study are available from C.F.-R. (carla.fernandezrico@mat.ethz.ch) or E.D. (eric.r.dufresne@cornell.edu) on reasonable request.
Code availability
The FFT code used in this study is available in the Supplementary Information and is also available from C.F.-R. (carla.fernandezrico@mat.ethz.ch) or E.D. (eric.r.dufresne@cornell.edu) on reasonable request.
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Acknowledgements
C.F.-R. acknowledges funding from the ETH Zürich Fellowship; V.B., from Adolphe Merkle Foundation and ERC Advanced Grant PrISMoID (833895); S.H., from SNF Ambizione grant (PZ00P2186041); and E.R.D., from the Swiss National Science Foundation NCCR for Bioinspired Materials. We thank N. Xue, K. Parkatzidis, K. Rosowski, D. Zwicker and D. Kochmann for useful discussions.
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Contributions
C.F.-R. and E.R.D. conceived the project and designed the experiments. C.F.-R., S.S. and C.L. performed the experiments, with input from A.S. and T.S. C.F.-R., R.W.S. and E.R.D. analysed and interpreted the experiments. V.B. performed the skeletonization analysis. H.O., P.C. and L.D.L. developed the theory and simulations, with input from R.W.S., S.H. and E.R.D. C.F.-R. and E.R.D. wrote the paper with inputs from all authors. E.R.D. supervised the project.
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Nature Materials thanks Mikko Haataja and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Supplementary Information
Supplementary Sections 1–13 and Figs. 1–15.
Supplementary Video 1
Confocal microscopy stack of a bicontinuous microstructure formed in 800 kPa PDMS. The field of view is 8 × 8 μm2 and the z step is 0.1 μm.
Supplementary Video 2
Confocal microscopy stack of a bicontinuous microstructure formed in 350 kPa PDMS. The field of view is 20 × 20 μm2 and the z step is 0.1 μm.
Supplementary Video 3
Confocal microscopy stack of a bicontinuous microstructure formed in 350 kPa PDMS. The field of view is 20 × 20 μm2 and the z step is 0.1 μm.
Source data
Source Data Fig. 1
Data used for the FFT analysis shown in Fig. 1f.
Source Data Fig. 2
FFT data and the corresponding peak analysis shown in Fig. 2c–f.
Source Data Fig. 3
Data used for the phase diagrams shown in Fig. 3d,e. The standard errors are included when appropriate.
Source Data Fig. 4
Data used for the phase diagrams shown in Fig. 4b–d. The standard errors are included when appropriate.
Source Data Fig. 5
Data for the strain–stress curves shown in Fig. 5b(ii).
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Fernández-Rico, C., Schreiber, S., Oudich, H. et al. Elastic microphase separation produces robust bicontinuous materials. Nat. Mater. 23, 124–130 (2024). https://doi.org/10.1038/s41563-023-01703-0
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DOI: https://doi.org/10.1038/s41563-023-01703-0
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