title: Bioinspired large-scale aligned porous materials assembled with dual temperature gradients.
abstract: Natural materials, such as bone, teeth, shells, and wood, exhibit outstanding properties despite being porous and made of weak constituents. Frequently, they represent a source of inspiration to design strong, tough, and lightweight materials. Although many techniques have been introduced to create such structures, a long-range order of the porosity as well as a precise control of the final architecture remain difficult to achieve. These limitations severely hinder the scale-up fabrication of layered structures aimed for larger applications. We report on a bidirectional freezing technique to successfully assemble ceramic particles into scaffolds with large-scale aligned, lamellar, porous, nacre-like structure and long-range order at the centimeter scale. This is achieved by modifying the cold finger with a polydimethylsiloxane (PDMS) wedge to control the nucleation and growth of ice crystals under dual temperature gradients. Our approach could provide an effective way of manufacturing novel bioinspired structural materials, in particular advanced materials such as composites, where a higher level of control over the structure is required.
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Bai
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.; Laboratoire de Physique des Surfaces et Interfaces, Université de Mons, Mons 7000, Belgium.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Delattre
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Antoni P
authors.initials: AP
authors.lastname: Tomsia
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.; Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Robert O
authors.identifier: 0000-0002-0501-6998
authors.initials: RO
authors.lastname: Ritchie
keywords: Biomimetic; ceramic scaffolds; freeze casting; ice nucleation; nacre
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