Chemical Synthetic Route towards "Colloidal Molecules"
Chemical Synthetic Route towards "Colloidal Molecules"
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DOI：
10.1002/anie.200802562
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发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Ravaine, Serge
中科院分区：
文献类型：
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作者：
Perro, Adeline;Duguet, Etienne;Ravaine, Serge
在过去的世纪中，对胶体粒子进行了广泛研究的领域包括凝聚态物理学、生物学、光学、材料科学和化学。我们目前对各种物理现象的理解和我们制造新功能材料的能力都大大丰富了合成策略的发展，这些策略能够产生大量具有良好尺寸均匀性的胶体实体。然而，大多数可用的单分散胶体材料是球形的，因为界面自由能的最小化强烈地驱动颗粒采用这种形状。[1]这极大地限制了可以通过使用这些胶体作为构建块来工程化的新结构的数量。例如，球形胶体结晶成三维周期性晶格，最近允许出现一个非常活跃的研究领域-光子胶体晶体，称为人工蛋白石。然而，这些晶体的光衍射特性是相当有限的，因为它们的面心立方晶格，这是由球体堆积而成的。据预测，具有较低对称度的晶体，例如金刚石晶格，可以表现出完全的光子带隙。为了构建这样的光子晶体，需要具有非球形形状的定义明确的胶体。货车Blaaderen最近引入了“胶体分子”这个优雅的术语，[2]这是考虑到球形胶体可以被视为原子，并且分子可以形成比原子更复杂的材料。因此，大量胶体的可重复制造具有良好的化学组成，表面性质，尺寸和形状的均匀性是一个巨大的挑战。[3]在过去的十年中，人们的努力导致了各种形状的非球形胶体的发展（如棒，[4-6]线，[7]三角形，[8]棱柱，[9]立方体，[10]椭圆体，[11]八面体，[12]四足体，[13]），但这些样品中很少有结合了尺寸和形状的真正单分散性和足够大的产量的要求。一个有前途的合成过程涉及使用物理模板，以更好地控制这两个参数。二维基底上的微图案化带电单层[14-17]或浮雕结构[18-23]用于制造具有高排列精度但数量非常少的胶体的单或二元簇。三维模板，如液体[24]或乳液液滴[25，26]也被用来形成具有良好控制的尺寸和形态的复杂胶体组装体。例如，基于含有聚合物微球的水包油乳液的产生和随后的受控油蒸发的聪明方法首先由Manoharan等人开发，[27-29]并导致含有精确数量的聚合物微球的聚集体。Cho等人将该程序扩展到通过使用油包水乳液生产具有不同形态的胶体[30]和二元簇[31]。我们最近报道了一种简单的化学路线，用于通过调节二氧化硅种子的数量和PS胶乳颗粒的数量之间的比率来生产由结合到二氧化硅核的聚苯乙烯（PS）胶乳颗粒制成的两相胶体。特别是，我们观察到当比例分别接近1和8时，雪人状[32]和章鱼状胶体[33]的形成。我们注意到，轻微的多分散性的大小的二氧化硅种子的主要原因是形成的胶体与可变数量的PS胶乳颗粒。这个...
A non-exhaustive list of fields in which extensive research has been dedicated to colloidal particles during the past century includes condensed matter physics, biology, optics, materials science, and chemistry. Both our current understanding of various physical phenomena and our capability to fabricate new functional materials have been considerably enriched by the development of synthetic strategies that are capable of generating copious quantities of colloidal entities of good size uniformity. Nevertheless, most of the available monodisperse colloidal materials are spherical, as the minimization of the interfacial free energy strongly drives a particle to adopt such a shape.[1] This strongly limits the number of new structures which can be engineered by using these colloids as building blocks. For instance, the crystallization of spherical colloids into three-dimensional periodic lattices has recently allowed the emergence of a very active field of research—photonic colloidal crystals, known as artificial opals. Nevertheless, the light diffraction properties of these crystals are rather limited because of their face-centered cubic lattice, which results from the packing of spheres. It has been predicted that crystals with a lower degree of symmetry, such as the diamond lattice, can exhibit a full photonic bandgap. To build such photonic crystals, well-defined colloids with nonspherical shapes are required. Van Blaaderen recently introduced the elegant term of “colloidal molecules”,[2] which takes into account that spherical colloids can be treated as if they were atoms and that molecules can form more complex materials than can atoms. Therefore, the reproducible fabrication of large amounts of colloids that have a good uniformity in chemical composition, surface properties, size, and shape is a huge challenge.[3] Intensive efforts during the last decade have led to the development of nonspherical colloids of various shapes (such as rods,[4–6] wires,[7] triangles,[8] prisms,[9] cubes,[10] ellipsoids,[11] octahedra,[12] tetrapods,[13]), but few of these samples combined the requirements of a true monodispersity in size and shape and the production of sufficiently large quantities. A promising synthetic procedure involves the use of a physical template to better control these two parameters. Micropatterned charged monolayers [14–17] or relief structures [18–23] on two-dimensional substrates were used to fabricate mono or binary clusters of colloids with high-arrangement accuracies, but in very small quantities. Three-dimensional templates such as liquid [24] or emulsion droplets [25, 26] were also exploited to form complex colloidal assemblies with well-controlled sizes and morphologies. For example, a clever approach based on the generation of oil-in-water emulsions containing polymer microspheres and the subsequent controlled oil evaporation was first developed by Manoharan et al.,[27–29] and led to aggregates that contain a precise number of polymer microspheres. This procedure was extended by Cho et al. to the production of colloids with different morphologies [30] and of binary clusters [31] by using water-in-oil emulsions. We have recently reported a facile chemical route for producing biphasic colloids made of polystyrene (PS) latex particles bound to a silica core by adjusting the ratio between the number of silica seeds and the number of PS latex particles. In particular, we have observed the formation of snowmanlike [32] and octopod-like colloids [33] when the ratios are close to 1 and 8, respectively. We noticed that a slight polydispersity in size of the silica seeds was the principal cause of the formation of colloids with a variable number of PS latex particles. This …