Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.; Laboratoire de Physique des Surfaces et Interfaces, Université de Mons, Mons 7000, Belgium.
Sci Adv. 2015 Dec 11;1(11):e1500849. doi: 10.1126/sciadv.1500849. eCollection 2015 Dec.
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.
天然材料，如骨骼、牙齿、贝壳和木材，尽管具有多孔性且由较弱的成分构成，但它们却表现出了优异的性能。它们经常为设计高强度、高韧性和轻量级材料提供灵感。尽管已经引入了许多技术来制造此类结构，但仍然难以实现孔隙的长程有序和最终结构的精确控制。这些限制严重阻碍了旨在更大应用的分层结构的规模化制造。我们报告了一种双向冻结技术，成功地将陶瓷颗粒组装成具有大尺度排列、层状、多孔、珍珠层状结构和厘米级长程有序的支架。这是通过用聚二甲基硅氧烷（PDMS）楔形物修饰冷指来实现的，以在双温度梯度下控制冰晶的成核和生长。我们的方法可以为制造新型仿生结构材料提供一种有效的途径，特别是在需要对结构进行更高水平控制的复合材料等先进材料领域。
