Two-Dimensional and Magic Size Layers of Metal Thiolates: Synthesis and Nanocalorimetry Characterization

技术概要： PI建议在材料研究部固态和材料化学计划的支持下合成和表征极薄的Ag硫醇盐（AgSR）层。 晶体的形状和大小多种多样，但有些晶体比其他晶体更特殊。这些特殊的尺寸，通常被称为幻数尺寸，在材料化学和物理学中非常有趣，因为它们通常是材料独特的潜在性质的证据。AgSR是一种有趣的聚合物，因为它生长为堆叠的平坦双层。 PI设想层状AgSR是自下而上自组装超结构的新模型构建块，可用于物理，化学，生物和微电子技术中的各种新材料应用。PI最近开发了一种新的合成方法，使用金属纳米颗粒生成大的AgSR晶体片。 这些晶体的直径为1微米，高度可达约30层厚，表面几乎是原子级平坦的（Langmuir 2009）。在这个建议中的一个主要目标是利用不寻常的平面属性的AgSR和扩展这种新的合成路径，以产生晶体的基本最小厚度，一层二维AgSR晶体。 这种单层晶体是自下而上自组装合成的最终起点。 2004年石墨烯的发现已经挑战了传统的智慧，即这些薄晶体不可能存在，因为部分由于熔化温度降低（尺寸依赖性熔化）而固有的不稳定性。 该提议的主要目的是测量这些1层晶体的熔化，这是迄今为止从未做过的。 这一目标将使用纳米热量计来实现。 这些结构可以用来研究热力学和尺寸依赖的熔化现象与单层控制的晶体尺寸，这是不可能的，除了集群束。PI建议使用NanoDSC研究该系统中的尺寸效应，以及液晶和亚稳相的形成。非技术摘要： 这项工作的科学影响将是为微电子工业的应用开发新的合成方法。此外，在热分析中开发的新表征技术将大大扩展我们在非常小的尺寸尺度上探测材料特性的科学能力，这对纳米技术的进步非常有用。 这项研究的广泛影响将包括纳米技术领域研究生的教育和培训以及新合成方法的开发。学生将接受使用微电子技术制造MEMS器件和使用自组装合成方法的教育和培训。几乎所有的PI培训的学生目前都在微电子行业工作。 除了正式的期刊文章，这项工作的传播将在会议上的形式由双方PI和研究生和本科生沿着在专门的热分析会议的纳米热量测定短期课程。 通过进一步开发合成方法和NanoDSC技术的能力，这项工作将增加该国基础科学和技术的制造和仪器基础设施。 预计将与西班牙和加拿大的研究小组以及美国的其他研究小组在热分析领域开展科学合作。

TECHNICAL SUMMARY: The PI proposes to synthesize and characterize extremely thin layers of Ag thiolate (AgSR) with the support from the Solid State and Materials Chemistry program in the Division of Materials Research. Crystals form in a variety of shapes and sizes but some crystals are more special than others. These special sizes, often referred to as Magic Number Sizes, are of great interest in materials chemistry and physics because often they are evidence of unique underlying properties of the material. AgSR is an interesting polymer in that it grows as stacked flat bilayers. The PI envisions lamellar AgSR to be a new model building block for bottom-up self assembly of superstructures that can be used in a variety of new material applications in physics, chemistry, biology and microelectronic technologies. The PI recently developed a new synthesis method using nanoparticles of metal which generates large AgSR crystal platelets. These crystals have diameters of 1 micron and heights of up to ~30 layers thick with nearly atomically flat surfaces (Langmuir 2009). One major objective in this proposal is to exploit the unusual planar attributes of AgSR and to extend this new synthesis path to produce crystals of the fundamental minimum thickness, one-layer two-dimensional AgSR crystals. This one-layer crystal is the ultimate starting point for bottom-up self-assembly synthesis. Discovery in 2004 of graphene has defied the conventional wisdom that these thin crystals could not exist because of an inherent instability in part due to reduced melting temperature (size-dependent melting). A major objective of this proposal is to measure the melting of these 1-layer crystals which to date has never been done. This goal will be accomplished using Nanocalorimetry. These structures can be used to study thermodynamics and size-dependent melting phenomenon with single-layer control of crystal size which has been implausible except for cluster beams. The PI proposes to study size-effects in this system using NanoDSC in addition to the formation of liquid crystal and metastable phases.NON-TECHNICAL SUMMARY: The scientific impact of this work will be in the development of generating new synthesis methods for applications in the microelectronics industry. Furthermore the new characterization techniques developed in thermal analysis will greatly expand our scientific ability to probe material properties at a very small size scale which is useful for advancement in Nanotechnology. The broad impact of this research will include the education and training of graduate students in the field of nanotechnology and the development of new synthesis methods. The students will be educated and trained in fabrication of MEMs devices using microelectronic techniques and in using self-assembly synthesis methods. Almost all of the students who have been trained by the PI are currently working in the microelectronics industry. In addition to formal journal articles, the dissemination of this work will be in the form of conference talks given by both the PI and graduate and undergraduate students along with Nanocalorimetry short courses in specialized Thermal Analysis conferences. By further developing the capabilities of the synthesis methods and NanoDSC technique, this work will add to the fabrication and instrumentation infrastructure of the country for basic science as well as for technology. Scientific collaborations are expected to be developed in the area of Thermal Analysis with groups in Spain and Canada as well as other research groups in the United States.