Driving diffusionless transformations in colloidal crystals using DNA handshaking
Driving diffusionless transformations in colloidal crystals using DNA handshaking
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DOI：
10.1038/ncomms2206
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发表时间：
2012-11-01
影响因子：
16.6
通讯作者：
Crocker, John C.
中科院分区：
文献类型：
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作者：
Casey, Marie T.;Scarlett, Raynaldo T.;Crocker, John C.
许多晶体，如金属晶体，可以通过无扩散转变从一种对称性转变为另一种具有较低自由能的对称性。在这里，我们创造了二元胶体晶体组成的聚合物微球，拉在一起的DNA桥，诱导特定的，可逆的吸引力之间的两种微球。取决于不同的相互作用的相对强度，悬浮液自发地形成具有CsCl和CuAu-I对称性的组成有序的晶体，或者当缓慢冷却时形成无序的固溶体晶体。我们的观察表明，CuAu-I晶体的形成从CsCl母体晶体的无扩散转变，类似于铁的马氏体相变。详细的模拟证实，CuAu-I是不是动力学直接从流体成核访问，但确实有一个较低的自由能比CsCl。这种结构转换发生的容易性表明了创造独特的超材料的新方法，这些材料具有否则可能在动力学上无法到达的结构。
Many crystals, such as those of metals, can transform from one symmetry into another having lower free energy via a diffusionless transformation. Here we create binary colloidal crystals consisting of polymer microspheres, pulled together by DNA bridges, that induce specific, reversible attractions between two species of microspheres. Depending on the relative strength of the different interactions, the suspensions spontaneously form either compositionally ordered crystals with CsCl and CuAu-I symmetries, or disordered, solid solution crystals when slowly cooled. Our observations indicate that the CuAu-I crystals form from CsCl parent crystals by a diffusionless transformation, analogous to the Martensitic transformation of iron. Detailed simulations confirm that CuAu-I is not kinetically accessible by direct nucleation from the fluid, but does have a lower free energy than CsCl. The ease with which such structural transformations occur suggests new ways of creating unique metamaterials having structures that may be otherwise kinetically inaccessible.