Collaborative Research: Line-Active Amphiphiles for Nanostructure Stability

技术总结这项研究项目将促进对线活性分子(在提案中称为线性剂)如何被用来改变分子单分子层中纳米和介观特征的线张力的基本理解。控制线张力的能力将对使用下一代纳米光刻方法创建的对象的稳定性至关重要；此外，线性处理剂将允许创建类似于3D胶束或微乳液的自组织2D特征。该战略将基于通过朗缪尔-布洛杰特(LB)沉积和相关的自组装方法制备的双组分单分子膜和三组分单分子膜中的分子聚集。关键组成部分包括合理设计和合成具有线活性的分子物种，这些分子物种在三维(3D)胶束、双层和微乳液中扮演着类似于两亲性表面活性剂分子的二维(2D)角色。与3D表面活性剂具有疏水和亲水区域的方式相同，这些乳化剂分子将拥有两个不同的疏水分子部分(要么是不同的尾部，要么是单个尾部内的块)；每个部分都被设计成与相分离的双组分单分子膜的各个组分中的一个有利地相互作用。这个合作团队之前的工作集中在具有一个碳氢化合物尾部或嵌段和一个氟化尾部或嵌段的链段。这些化合物成功地降低了富含碳氢化合物和氟碳化合物的单层相之间的线张力；还观察到了独特的2D自组装成类似胶束的纳米级团簇。该项目的具体目标是(1)更深入地了解导致氟碳/碳氢化合物混合单层体系中直链乳化剂行为的分子机制，以及(2)通过设计和合成直链乳化剂来推广氟碳/碳氢化合物体系以外的直链乳化剂现象，用于其他二元单层混合物，包括碳氢/有机硅、饱和/不饱和碳氢化合物和胆固醇/脂肪。随着器件和材料变得越来越小，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，如凝聚或纳米级图案的降解。出于这个原因，纳米级结构的制造需要添加分子稳定剂--分子在表面分配并降低表面张力。这种稳定剂背后的科学对于传统的三维材料，如胶体和乳剂，甚至纳米颗粒，是相当好的理解的。然而，对于稳定二维纳米结构(即表面制造的纳米级图案)所必需的分子，还没有这样的科学。这种表面纳米粒子的稳定性是未来在分子电子学、催化、生物传感器和生物材料中应用的必要条件。这一合作研究项目包括两所不同大学的两个不同学科，将寻求扩大妇女和少数群体在科学和教育方面的参与。将鼓励所有参与者加入他们当地的专业协会，并参加地方和国家会议，以推动我们的宣传工作。此外，通过参与各种教育和外展计划(例如，REUS、RET、NUE、GAANN、CU-Discovery学习中心、CU K-12外展的材料科学、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拉丁裔外展和韦尔奇夏季学者)，研究人员将继续与学生、教师和其他社区成员分享这一项目。此外，该项目将基本发现和潜在的技术影响结合在一起，将提供一个理想的平台，从这个平台向公众传达研究的兴奋。

TECHNICAL SUMMARYThis research project will advance the 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 critical to the stabilization of objects created using next generation nanolithographic methods; in addition, linactants will permit the creation of self-organized 2D features that are analogous to 3D micelles or microemulsions. The strategy will be based 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 molecular species that play a two-dimensional (2D) role analogous to that 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; also observed was distinctive 2D self-assembly of the linactants into nm-scale clusters that were analogous to micelles. The specific objectives of this project are (1) to obtain a deeper 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 other binary monolayer mixtures, including hydrocarbon/silicone, saturated/unsaturated hydrocarbons, and cholesterol/lipid.NON-TECHNICAL SUMMARYThis project involves fundamental scientific research that will enable advances related to 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, such as coagulation or the degradation of nanoscale patterns. For this reason, the fabrication of nanoscale structures requires the addition of molecular stabilizers -- molecules that partition at surfaces and reduce the surface tension. The science behind such stabilizers is reasonably well-understood for traditional three-dimensional materials, such as colloids and emulsions or even nanoparticles. However, no such science exists for molecules that are necessary 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, RET, 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 other community members. Furthermore, the integration of basic discovery and potential technological impact in this project will provide an ideal platform from which to communicate the excitement of research to the public.