Fundamental Studies of Graphene Solutions: Exfoliation, Dispersion, and Stability

石墨烯溶液的基础研究：剥离、分散和稳定性

• 批准号: 1133813
• 负责人: Daniel Blankschtein
• 金额: $ 33.2万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-10-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1133813&HistoricalAwards=false
• 关键词: Fundamental; Studies; Graphene; Solutions; Exfoliation

1133813BlakschteinIntellectual Merit. In this project, the investigators seek to understand the origin of the interactions between suspended graphene with surrounding solvent/surfactant molecules via large-scale molecular dynamics simulations. They will quantify these interactions by calculating the potential of mean force between graphene sheets in solvents or aqueous surfactant solutions to establish a library of thermodynamic properties for dispersed graphene sheets. A theoretical framework that combines molecular dynamics simulations and kinetic theories of colloid aggregation will be developed to further design optimal solvent/surfactant molecules which can stabilize graphene dispersions efficiently. Experimentally, they will produce layer-controlled graphene dispersions using ionic graphite intercalation compounds (GICs). By carefully controlling the intercalation kinetics, the PIs will synthesize high-quality Stage-2 and Stage-3 GICs, which are expected to be excellent precursors for bilayer and trilayer graphene dispersions. Systematic characterizations of graphene dispersions will be carried out to optimize the exfoliation process such that the produced dispersions are sufficiently concentrated, and that the graphene flakes are large enough, for conventional photolithography in which they will be deposited on a target substrate. Advanced separation techniques will also be developed to produce monodisperse bilayer and trilayer graphene solutions. The fundamental and practical insights gained from the proposed modeling and experiments will be used to guide the fabrication of electronic devices. The combined expertise of the two PIs across colloid science, engineering nanotechnology, computer simulations, and molecular modeling will enable rapid progress towards engineering graphene solutions for device manufacturing.The development of an advanced technique to exfoliate graphene in liquid phases will greatly increase the capability to produce AB-stacked bilayer and trilayer graphene for practical applications, such as fabricating electronic devices. In addition, fundamental insights into the interactions between graphene and other molecules will also contribute to the overall fundamental and practical of the kinetic behavior of graphene in the liquid phase. Ultimately, such knowledge can lead to the rational design of better media for graphene dispersions.Broader Impacts. Due to their distinct electronic properties, stacked bilayer and trilayer graphene have shown extraordinary potential for next-generation optoelectronic and microprocessor applications. These promising materials, nevertheless, require new synthesis methods to effectively control the number of AB-stacked layers through graphite exfoliation and advanced processing techniques. Solution graphene dispersions are promising raw materials for printable electronics and nanocomposites, and most importantly, this approach represents the only possible route at this time for the mass-production of AB stacked bi- and tri-layer graphene. However, since the first graphene solution was reported in 2008, there are still many unanswered questions and technical bottlenecks that hinder the progress of this field. Although experiments have shown that the distribution of graphene layer numbers highly depends on the choice of solvents or surfactants used, very little is known about the molecular origin of the interactions between graphene and solvent/surfactant molecules, including correlating these interactions with the colloidal stability of the graphene solution. In addition, regardless of the methods used to produce solution-phase graphene, its size, shape, and number of stacked layers are all polydisperse. Engineering approaches that can directly control the size and the stacking geometry (by narrowing their distributions) of the exfoliated graphene flakes will be developed.The modeling and experimental advances made will be incorporated into courses and workshops at MIT that will expose a larger scientific audience to the fundamentals of graphene dispersion and stabilization in liquid phases, as well as to modeling these phenomena at the molecular level. The students involved in the proposed research at both the graduate an undergraduate level will gain intellectually and professionally from the integrated experimental/modeling research proposed here.

1133813Blakschtein智慧的功绩。在这个项目中，研究人员试图通过大规模的分子动力学模拟来了解悬浮石墨烯与周围的溶剂/表面活性剂分子之间相互作用的起源。他们将通过计算溶剂或表面活性剂水溶液中石墨烯之间的平均作用力势来量化这些相互作用，以建立分散石墨烯的热力学性质库。一个结合分子动力学模拟和胶体聚集动力学理论的理论框架将被用来进一步设计能够有效稳定石墨烯分散体的最佳溶剂/表面活性剂分子。在实验上，他们将使用离子石墨层间化合物(GIC)生产层控石墨烯分散体。通过仔细控制插层动力学，PI将合成高质量的第二阶段和第三阶段石墨烯，有望成为两层和三层石墨烯分散体的优良先驱体。将对石墨烯分散体进行系统的表征，以优化剥离过程，以使产生的分散体足够集中，并且石墨烯薄片足够大，用于传统的光刻，在传统光刻中，它们将被沉积在目标衬底上。先进的分离技术也将被开发出来，以生产单分散的双层和三层石墨烯溶液。从所提出的建模和实验中获得的基本和实用的见解将用于指导电子器件的制造。这两个PI在胶体科学、工程纳米技术、计算机模拟和分子建模方面的专业知识相结合，将使设备制造的石墨烯工程解决方案迅速取得进展。开发一种在液体中剥离石墨烯的先进技术将极大地提高生产AB堆叠的双层和三层石墨烯的能力，用于实际应用，如制造电子器件。此外，对石墨烯和其他分子相互作用的基本见解也将有助于全面了解石墨烯在液体中的动力学行为。最终，这些知识可以指导合理设计更好的石墨烯分散介质。层叠式双层和三层石墨烯由于其独特的电学性质，在下一代光电子学和微处理器应用方面显示出了非凡的潜力。然而，这些有希望的材料需要新的合成方法来通过石墨剥离和先进的加工技术来有效地控制AB堆叠层的数量。溶液石墨烯分散体是制造可印刷电子器件和纳米复合材料的很有前途的原材料，最重要的是，这种方法是目前批量生产AB堆叠的双层和三层石墨烯的唯一可能途径。然而，自2008年报道第一个石墨烯解决方案以来，仍有许多悬而未决的问题和技术瓶颈阻碍了该领域的进展。虽然实验表明石墨烯层数的分布高度依赖于所使用的溶剂或表面活性剂的选择，但关于石墨烯与溶剂/表面活性剂分子之间相互作用的分子起源，包括这些相互作用与石墨烯溶液的胶体稳定性之间的关联，人们知之甚少。此外，无论采用哪种方法生产溶液相石墨烯，其大小、形状和堆积层数都是多分散的。将开发可以直接控制剥离的石墨烯薄片的尺寸和堆积几何形状(通过缩小其分布)的工程方法。所取得的建模和实验进展将被纳入麻省理工学院的课程和研讨会，这些课程和研讨会将向更多的科学受众展示石墨烯在液体中分散和稳定的基本原理，以及在分子水平上模拟这些现象。参与拟议研究的本科生和研究生都将从这里提出的综合实验/建模研究中获得智力和专业上的收益。