Realizing non-close-packed colloidal crystals using directional-bonding superparticles

该方案采用了一种创新的方法来制造分层材料，即所谓的超材料，它有望拥有传统材料中不存在的特性，例如负折射率材料。这些负折射率材料被用于开发超透镜（允许在衍射极限以下成像）、光学纳米光刻和其他领域，如制造雷达微波吸收（即隐身）材料。他们已经成功地开发了制造超材料部件的新方法，并在这项提议中寻求扩大工艺规模，然后在计算机模拟的帮助下确定如何最好地将单个部件组装成超材料。PI有很强的外联记录，开发细胞力学的教学材料，并通过有线电视和讲座系列向当地高中传播，并在他的研究活动中包括代表性不足的群体。他已经让一名有前途的非裔美国REU学生参与了这项工作，并将继续在新项目下招募和培训代表性不足的学生。PI和Co-PI提出了一种“逆自组装”方法，即他们从一个健壮组装的超结构开始，然后询问应该使用什么样的结构较小的构建块（簇）。这个问题比表面上看起来要困难得多，因为已经证明星团的排列不仅取决于星团的形状，而且还受到粒子间定向熵相互作用的强烈影响。研究人员将使用他们先前开发的胶体晶体模板技术来定制定义几何填料的簇，并将使用模拟来帮助探索将簇组装成超结构或超材料的相图和动力学。

This proposal uses an innovative approach to make hierarchical materials, the so-called metamaterials, which hold promise of possessing properties that do not exist in conventional materials, such as negative refractive-index materials. These negative-index materials are finding uses in the development of superlenses (to allow imaging below the diffraction limit), in optical nanolithography and in other fields, such as for making radar-microwave absorption (i.e., stealth) materials. They have been successful in developing novel ways to make the component pieces for metamaterials and seek, in this proposal, to scale up the process and then determine, with the aid of computer simulations, how best to assemble the individual pieces into metamaterials.The PI has a strong record of outreach, developing instructional materials on cell mechanics and disseminating it via cable television and lecture series to local high schools, and including underrepresented groups in his research activities. He has already involved a promising African-American REU student in this work and will continue to recruit and train underrepresented students under the new project.An "inverse self-assembly" approach is proposed by the PI and Co-PI, whereby they start with a robustly assembled super-structure and then ask what structured smaller building blocks (clusters) should be used. This problem is more difficult than it appears because the packing of the clusters have been shown not to simply depend on the cluster shape, but is rather strongly influenced by the directional entropic interactions between the particles. The investigators will use their previously developed colloidal crystal-templating technique to custom make clusters of defined geometrical packing and will use simulations to aid in exploring the phase diagram and kinetics of assembling the clusters into super-structures or metamaterials.