磁场调控的复杂流体基超材料及负折射行为研究

Metamaterials are the most important frontier topic in physical and material sciences. Due to the innormal electric-manetic propertis, metamaterials have potential uses in various fields. Up to now, the design and preparation of metamaterials are focused on hard matter system, which are showing some problems including the difficult fabrication of metamaterials that respond at high-frequency, inefficiently active control strategies for material structure with external fields, and poor flexibility. Having considered the good flexibility and smart tunability of soft matter, the researchers recently have started to study soft matter-based metamaterials and their negative reflection behavior in theory and simulation. Combining the present theoretical results and our experiences about smart complex fluids, we in this project will focus on the design and preparation of a novel kind of magnetically tunable complex fluid-based metamaterial showing a negative reflection behavior. We will experimentally investigate how to achieve the anisotropic dielectric properties and the resulted negative reflection behavior in the complex fluid by controllably adjusting the formation of ordered chain-like structure with external magnetic fields and further study the dependence of negative reflection index on external magnetic field strength. Furthermore, we also exploit a new way to control the continuous change of negative reflection index by adjusting the locally ordered level of chain-like structure in complex fluids with a radical magnetic field. The successful design and preparation of the novel complex fluid-based metamaterial with good flexibility and magnetically tunable properties will provide a new possible way to prepare metamaterials and open a door to develop the soft and tuable metamaterial devices in future.

超材料是当今物理、材料等学科的研究前沿，具有广阔应用前景。目前构筑超材料主要基于硬物质（或固体材料），其问题是大面积高频超材料制备困难、成型后结构和行为很难随意调节、柔性较差。认识到软物质的柔性、智能可调等特征，研究者已开始初探基于软物质的超材料构筑及其可调行为，然而目前的研究仍仅限于理论。本项目根据现有理论，结合我们在电磁调控复杂流体方面的研究基础，拟基于材料设计与可控制备，从实验上制备出可磁场调控实现负折射效应的复杂流体超材料，研究外场诱导复杂流体的有序结构形成、介电强各向异性转变、负折射效应产生及随外场可调变化规律，并利用软物质结构随外场主动可调特点，探索用辐射状非均匀磁场调控流体局域有序结构进而诱导体系介电性质梯度变化，实现梯度调制负折射率的新方法。希望这种结构柔性、性能可调的新颖复杂流体超材料的实验实现不仅突破由硬物质构筑超材料的传统思路，也为未来开发柔性可调超材料器件提供基础。

超材料具有不同于传统材料的反常物理性质，因此具有重要研究意义和潜在应用价值。当前构筑超材料主要基于硬物质，它存在光频段超材料大面积制备困难、缺乏柔性、环境自适应性差等问题。本项目基于现有理论，开展了具有柔性、外场可调的复杂流体基、石墨烯基软超材料研究，调查了外场调控实现负折射、宽频红外全吸收、宽角双带红外全吸收、隐身斗篷、太赫兹分束功能及其随外场可调变化规律；探索了通过表面修饰获取具有高稳定和增强场响应行为的纳米复杂流体的方法，研制了多种具有高稳定和增强场响应行为的纳米流体新体系，为智能可调流体超材料和场控智能流体的研究提供了基础。主要结果有：.1）提出并设计了新颖的外场可调纳米棒流体基软超材料，研究了通过外场调控流体的有序结构实现场致反常光学行为，如光频负折射、宽频红外全吸收、零折射率与多频隐身等，证实了通过调节外场强度和分布调控光学行为能力，为开发主动或半主动智能软超材料器件提供了基础。2）利用石墨烯超薄、柔性、太赫兹表面等离子体响应、电导率随费米能级改变等特点，构建了新颖的外场可调超薄石墨烯基超材料，在石墨烯/介质多层堆垛双曲体系中发现了外场可调宽角双带红外全吸收行为，在反平行梯形排列的石墨烯超表面中证实了太赫兹频域的外场可调分束镜功能。3）探索了通过分子修饰和纳米包覆研制高分散稳定和具有增强的场响应行为的一维和二维油基纳米流体新方法，研制出包括硅烷修饰碳管、笼状硅烷修饰石墨烯、SiO2和聚合物包覆石墨烯等多种具有高稳定和增强的场响应行为的油基纳米流体新体系，为场控流体超材料和智能流体的研究提供了基础。.该项目发表SCI论文13篇（IF>3.0），其中封面文章1篇。论文被SCI他引102次，部分结果被英国nanotechweb、加拿大Advances in Engineering网站作为亮点报道。项目组成员参加国际会议3次、国内会议10次。依托该项目培养博士研究生3名（硕博连续在读）、硕士研究生9人（毕业8人），其中2人获校优秀硕士论文，4人次获国家奖学金。