仿生材料多尺度设计与制备

（1）冰模板技术原理及其在材料多尺度结构调控方面的应用

冰模板技术是一种以冰晶为模板进行组装的材料制备技术，具有环保及可精确调控材料结构等特点。常规的定向冷冻主要通过调节冰晶的形貌来实现各种有序结构的可控制备。例如，通过改变温度场（如不同方向的温度梯度）或调控冷源表面性质（如冷源表面浸润性）等手段，可以调节冰晶在冷源表面的成核，并进一步调节所得材料的结构。这一方法在组织工程、航空航天以及能源等领域得到了广泛的应用。

Taking ice as templates, ice-templating method is an environmentally friendly method, which could assemble materials with a precise control of their structure. Normal directional freezing methods controls the materials’ structure through controlling the morphology of ice crystals. For example, ice nucleation on cold surface could be efficiently controlled by adjusting temperate fields (e.g., temperature gradient in different directions) or designing surface properties (e.g., surface wettability), and thus control the structure of materials. This method has been widely applied in fields such as tissue engineering, aerospace and energy industries.

（2）仿北极熊毛的多孔隔热织物

北极熊毛是一种保温性能优异的天然纤维，可以在寒冷的极地环境中保持北极熊的体温稳定，这种卓越的保温性能来源于北极熊毛特殊的中空结构。受此启发，我们将定向冷冻法与溶液纺丝相结合，开发了“冷冻纺丝”技术，获得了具有取向片层孔结构的多孔纤维。使用这种多孔纤维编织成的织物具有优异的隔热性能。当这一织物覆盖在兔子身上时，使用红外相机将难以观测到兔子表面和环境的温度区别，成功实现了对兔子的热隐身。这种仿北极熊毛多孔织物可以为人员或设备提供更为有效轻便的热防护，具有广泛的应用前景。

    Being able to keep polar bears’ body temperature stable in harsh arctic regions, polar bear hairs are considered as natural fibers with outstanding thermal insulating abilities, which comes from their sophisticated porous structure. Inspired by this, we combined traditional directional freezing and solution spinning to develop a novel “freeze-spinning” method, and fabricated fibers with aligned porous microstructure. Textile woven by the porous fibers showed excellent thermal insulating performance. When covered by this textile, ribbit became invisible under infrared camera, realizing thermal stealth. Therefore, this biomimetic textile is a promising candidate to provide effective and portable thermal protection for personnel and equipment, and has wide applications in many fields.

（3）受墨鱼骨启发的高机械效率多孔材料

墨鱼骨作为一种轻质高强的天然多孔材料，具有90%以上的孔隙度，但却能承受水下几百米的静水压，且在墨鱼复杂的运动过程中仍能保持机械稳性。Micro-CT数据显示天然墨鱼骨为层状结构，此外我们发现层间连接的墙壁是不对称S型波浪壁。通过精确调控上下振幅的不对称度，证明了墨鱼骨的不对称波浪壁结构可以同时实现高抗压缩和抗剪切的性能。此外，层状结构有助于提高能量吸收能力，并防止整体性破坏。受天然墨鱼骨结构启发，利用3D打印法设计制备了轻质、高强并且具有高能量吸收能力的新型多孔材料。该仿墨鱼骨材料可以承受超过自身55000倍的重量，未来可以应用于航空航天、轻量化汽车等领域。

Cuttlebone is a kind of natural lightweight materials (porosity>90%) with high strength, which can resist large hydrostatic pressure in the deep-sea environment and can withstand multiple loadings during intricate movements. The cuttlebone structure is constructed like lamellar septa based on micro-CT data. Furthermore, we found the connecting walls are asymmetric, distorted S-shaped. Through precisely controlling the wall asymmetry, we demonstrated the cuttlebone-like structure exhibits high compressive strength and shearing strength. Furthermore, the introduction of layered structure can largely enhance the energy-absorption capability, and can avoid catastrophic failure. Inspired by the cuttlebone's structure, lightweight and mechanically efficient materials are designed and fabricated through 3D printing. The cuttlebone-like material is capable of sustaining a weight more than 55 000 times its own, beneficial for many applications including aerospace structures and lightweight vehicles.

（4）仿木材多孔塑料

木头所具有的取向多孔结构赋予了其轻质高强等许多优异的性能。通过冰模板法对高分子单体乳液进行诱导组装，随后在低温下聚合并在室温下解冻，制备了具有仿木结构的高分子泡沫。与常规冰模板法相比，这一方法避免了对高分子体系水溶性以及干燥过程对冷冻干燥机的依赖。此外，调节温度场，还可以制备具有多层、正交取向以及具有负泊松比的径向取向等结构的仿木结构材料。与传统发泡技术相比，这一方法在泡沫塑料的孔结构及成分分布方面具有更突出的调控能力，为多功能、高性能高分子泡沫的设计和制备开辟了新思路。

The aligned porous structure of wood has endowed it with many excellent properties such as light weight and high strength. Through an ice-templated assembly of monomer/water emulsion, followed by cryo-polymerization and room temperature thawing, we have prepared a cellular plastic with wood mimetic structure. This work broke through the limits of normal ice-templating on the polymer solubility in water, and freed the drying process from the dependence on the freeze-dryer. In addition, by adjusting temperature fields, lots of porous structures such as the multi-layered, orthogonal aligned and radially aligned structures could be obtained, in which the radially aligned cellular plastic presented a negative Poisson's ratio. Compared to the traditional foaming, this technique showed better abilities to regulate the porous structures and composition distributions of cellular plastics. Meanwhile, it opens a new way for the preparation of the multifunctional and high performance cellular plastics.

（5）仿贝壳结构层状复合材料

天然贝壳珍珠母具有有机-无机交替的层状“砖-泥”结构，是一种典型的高强高韧天然结构材料。通过双向冷冻法，构筑两个方向的温度梯度，可以获得具有大面积取向结构仿贝壳材料。此方法可以应用于不同的材料体系，从而得到具有不同功能的材料。例如，应用于柔性电子器件领域，具有高强度，高延展性以及高韧性的仿贝壳膜材料；应用于航空航天领域，具有自修复和智能响应特点的新型高分子复合结构材料；应用于导热领域，具有强导热各向异性的复合结构材料等。

Nacre is a typical natural structural material with high strength and toughness with unique lamella “brick-and-mortar” structure. Using bidirectional freezing method and constructing temperature gradient in two directions, biomimetic materials with large-area aligned microstructure could be obtained. This method could be applied in different materials and prepare materials with different applications. For example, film with high strength, ductility and toughness could be applied in flexible electronic devices; novel organic-inorganic composite material with self-repairing and intelligent responding abilities has large potential in aerospace fields; thermally conductive material with three-dimensional filler network shows high thermal conductivity anisotropy, and thus could be widely used in thermal conductive fields.