Freeze Casting for Assembling Bioinspired Structural Materials

Abstract

Nature is very successful in designing strong and tough, lightweight materials. Examples include seashells, bone, teeth, fish scales, wood, bamboo, silk, and many others. A distinctive feature of all these materials is that their properties are far superior to those of their constituent phases. Many of these natural materials are lamellar or layered in nature. With its “brick and mortar” structure, nacre is an example of a layered material that exhibits extraordinary physical properties. Finding inspiration in living organisms to create bioinspired materials is the subject of intensive research. Several processing techniques have been proposed to design materials mimicking natural materials, such as layer‐by‐layer deposition, self‐assembly, electrophoretic deposition, hydrogel casting, doctor blading, and many others. Freeze casting, also known as ice‐templating, is a technique that has received considerable attention in recent years to produce bioinspired bulk materials. Here, recent advances in the freeze‐casting technique are reviewed for fabricating lamellar scaffolds by assembling different dimensional building blocks, including nanoparticles, polymer chains, nanofibers, and nanosheets. These lamellar scaffolds are often infiltrated by a second phase, typically a soft polymer matrix, a hard ceramic matrix, or a metal matrix. The unique architecture of the resultant bioinspired structural materials displays excellent mechanical properties. The challenges of the current research in using the freeze‐casting technique to create materials large enough to be useful are also discussed, and the technique's promise for fabricating high‐performance nacre‐inspired structural materials in the future is reviewed.

Role of Interface Interactions in the Construction of GO‐Based Artificial Nacres

“…The detailed discussion on these applications of GANs could be found in previous excellent reviews. [178] Last but not least, a prospective for GANs in the near future is proposed in Figure 8, which contains their theoretical simulation and experimental research. For example, the most of GANs have improved mechanical properties but decreased electrical conductivity compared with pure graphene film due to the addition of insulated bonders and building blocks.…”

Enhanced Adhesion of Polydimethylsiloxane Using an Interlocked Finger Structure

“…Therefore, the crystallites become connected, and the pores formed afterward have the same connectivity. Closed pores are rare in materials prepared by this technique, as has already been recognized …”

“…This novel adhesion improvement strategy based on surface pretreatment can work for many polymers if the polymer surface can be dissolved by a crystallizable solvent. This is similar to the general applicability of the directional melt crystallization technique itself, which has been applied to numerous materials . Numerous materials with low surface energies such as PDMS can benefit from this method.…”

“…The morphologies of the pores depended on the related variables such as temperature gradient, contact time, and concentration gradient. This surface treatment based on directional melt crystallization is similar to “ice templating,” “freeze casting,” or “directional freezing” methods except that all of these methods have been utilized to prepare bulk materials and have no dissolution step …”

In Situ Incorporation of Pores and Nanoparticles into Polymer Surfaces Using Melt Crystallization

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