Collaborative Research: Line-Active Amphiphiles for Nanostructure Stability

技术概述：拟议的研究将对如何使用线活性分子（在提案中称为linactants）来修改分子单层内纳米和中观尺度特征的线张力有一个基本的理解。控制线张力的能力对于稳定使用下一代纳米光刻方法创建的物体是必要的；此外，溶解剂的开发和使用将允许创建类似于3D胶束或微乳液的自组织2D特征。所提出的实验策略将依赖于Langmuir-Blodgett （LB）沉积和相关自组装方法制备的双组分和三组分单分子膜内的分子聚集。关键成分包括合理设计和合成线活性分子，这些分子在二维（2D）中发挥作用，类似于三维（3D）胶束、双层和微乳中的两亲性表面活性剂分子。与3D表面活性剂具有疏水性和亲水性区域的方式相同，这些活性剂分子将具有两个不同的疏水性分子部分（不同的尾部或单个尾部内的块）；每个部分被设计成与相分离的双组分单层膜的各自组分之一有利地相互作用。这个合作团队以前的工作重点是具有一个碳氢化合物尾部或块和一个氟化尾部或块的溶剂。这些化合物成功地降低了碳氢化合物和富含氟碳化合物的单层相之间的线张力；还观察到不同的二维自组装成类似胶束的纳米级团簇。该项目的具体目标是：(1)更清楚地了解导致氟碳/碳氢化合物混合单层体系中活性剂行为的分子机制；(2)通过设计和合成用于替代二元单层混合物的活性剂，包括碳氢化合物/有机硅、饱和/不饱和碳氢化合物和胆固醇/脂质，来推广氟碳/碳氢化合物体系之外的活性剂现象。本提案中概述的基础科学研究将导致技术重要和新兴的纳米技术领域的进步。随着器件和材料的小型化，表面和界面的影响变得越来越重要。特别是，表面张力的影响会导致不稳定性，从而引发纳米尺度图案和结构特征的退化。由于这个原因，制造功能性纳米级结构需要添加分子稳定剂——在表面分裂的分子，减少边缘和区域边界之间的表面张力。对于传统的三维材料，如胶束、乳液，甚至纳米颗粒，这些稳定剂背后的科学原理是相当好的理解。然而，对于稳定二维纳米结构（即在表面上制造的纳米级图案）所需的分子，没有这样的科学存在。这种表面纳米结构的稳定性对于分子电子学、催化、生物传感器和生物材料的未来应用是必需的。这个合作研究项目包括两所不同大学的两个不同学科，它将寻求扩大妇女和少数民族对科学和教育的参与。我们鼓励所有参与者加入当地的专业协会，并参加地方和国家会议，以促进我们的传播工作。此外，通过参与各种教育和推广项目（例如，REUs, RETs， NUE， GAANN， CU-发现学习中心，CU K-12推广材料科学，科罗拉多高中荣誉学院，休斯顿路易斯斯托克斯少数民族参与联盟，UH拉丁裔推广和韦尔奇暑期学者），研究人员将继续与学生，教师和广大社区成员分享这个项目。此外，将基础科学发现与技术和社会影响联系起来的提议提供了一个理想的平台，可以向公众传达研究的好处。

TECHNICAL SUMMARYThe proposed research will develop a fundamental understanding of how line-active molecules (called linactants in the proposal) can be used to modify the line tension of nano- and meso-scale features within molecular monolayers. The ability to control line tension will be necessary to stabilize objects created using next-generation nanolithographic methods; furthermore, development and use of linactants will permit the creation of self-organized 2D features that are analogous to 3D micelles or microemulsions. The proposed experimental strategy will rely on molecular aggregation within two- and three-component monomolecular films prepared by Langmuir-Blodgett (LB) deposition and related self-assembly methods. Key components include the rational design and synthesis of line-active molecules that play roles in two-dimensions (2D) that are analogous to those of amphiphilic surfactant molecules in three-dimensional (3D) micelles, bilayers, and microemulsions. In the same manner in which a 3D surfactant possesses hydrophobic and hydrophilic regions, these linactant molecules will possess two dissimilar hydrophobic molecular moieties (either distinct tails or blocks within a single tail); each moiety is designed to interact favorably with one of the respective components of a phase-separated two-component monolayer film. Previous work by this collaborative team focused on linactants having one hydrocarbon tail or block and one fluorinated tail or block. These compounds successfully reduced the line tension between hydrocarbon- and fluorocarbon-rich monolayer phases; distinctive 2D self-assembly of the linactants into nanometer-scale clusters analogous to micelles was also observed. The specific objectives of this project are (1) to obtain a clearer understanding of the molecular mechanisms leading to linactant behavior in fluorocarbon/hydrocarbon mixed monolayer systems, and (2) to generalize the linactant phenomenon beyond fluorocarbon/hydrocarbon systems by designing and synthesizing linactants for use in alternative binary monolayer mixtures, including hydrocarbon/silicone, saturated/unsaturated hydrocarbons, and cholesterol/lipid.NON-TECHNICAL SUMMARYThe fundamental scientific research outlined in this proposal will lead to advances in the technologically important and emerging field of nanotechnology. As devices and materials are made smaller and smaller, the influence of surfaces and interfaces becomes increasingly important. In particular, the influence of surface tension leads to instabilities that can instigate the degradation of nanoscale patterns and structural features. For this reason, the fabrication of functional nanoscale structures requires the addition of molecular stabilizers -- molecules that partition at surfaces and reduce the surface tension between edges and domain boundaries. The science behind such stabilizers is reasonably well understood for traditional three-dimensional materials, such as micelles, emulsions, and even nanoparticles. However, no such science exists for molecules that are needed to stabilize two-dimensional nanostructures (i.e., nanoscale patterns fabricated on surfaces). The stability of such surface nanopatterns is required for future applications in molecular electronics, cataysis, biosensors, and biomaterials. This collaborative research project, which encompasses two distinct disciplines at two separate universities, will seek to broaden the participation of both women and minorities in science and education. All participants will be encouraged to join their local professional societies and to attend local and national meetings to advance our dissemination efforts. Also, through their participation in a variety of educational and outreach programs (e.g., REUs, RETs, NUE, GAANN, CU-Discovery Learning Center, Materials Science from CU K-12 outreach, Colorado High School Honors Institute, Houston Louis Stokes Alliance for Minority Participation, UH Latino Outreach, and Welch Summer Scholars), the researchers will continue to share this project with students, teachers, and members of the community at large. Furthermore, the proposed effort to link fundamental scientific discovery with technological and societal impact offers an ideal platform from which to communicate the benefits of research to the public.