EXPLORATORY: Environmentally Friendly Formation of Self-Assembled Monolayers and Surface-Initiated Polymer Films in Carbon Dioxide

摘要CTS-0203183詹宁斯，G. KaneWeinstein，Randy DVanderbilt University探索：二氧化碳中自组装单分子层和表面引发聚合物膜的环境友好形成这项合作研究将调查使用环境友好的二氧化碳（CO2）作为溶剂，形成自组装单分子层（SAMs）和表面引发过程生长的聚合物膜。由于其小分子尺寸和与金属表面（如金）的弱相互作用，CO2是一种近乎理想的溶剂，可以促进形成密集的高度结晶的SAM，正如该项目的作者最近报道的那样。进一步的研究将探讨形成自组装膜到金从部分氟化的烷硫醇和共溶剂的影响的结构和单层膜的阻隔性能。这项研究还试图关联的第一次的表面平均结构和屏障性能的自组装膜，分别通过反射吸收红外光谱（RAIRS）和电化学阻抗谱（EIS），与它们的微观特性，如域的大小和缺陷含量，由扫描探针显微镜（SPM）确定。这项研究还将开发一类新的表面引发的，生活的聚合物膜的基础上的合成过程的多同系化。该膜是由硼封端的SAM引发的，并且具有有趣的性质，即可以选择聚合物膜的端基以产生各种各样的表面组合物。在这些膜的生长过程中，前体分子必须扩散通过生长的膜并在活性硼位点处反应，使得增强前体通过膜的传输的溶剂将增加膜生长的速率和膜的最终厚度。二氧化碳是一种潜在的有效的溶剂，用于增强这些新型聚合物膜的生长，由于其能够溶胀许多聚合物，其低粘度和零表面张力，以及许多小分子在CO2中的高扩散速率。此外，与必须在干燥箱中进行多次溶剂转移的有机溶剂的使用相比，在该聚合方法中使用CO2能够实现简单得多的一锅合成程序。 到目前为止，还没有以前的调查使用CO2在形成表面引发的聚合物膜，只有一个其他的研究涉及在CO2中形成自组装膜。该项目的成功完成将为通过环境友好的加工形成这些技术上重要的薄膜提供新的策略。 此外，该项目应增强二氧化碳材料加工的知识基础，并促进研究和工业中增加二氧化碳的使用。

AbstractCTS-0203183Jennings, G. KaneWeinstein, Randy DVanderbilt UniversityEXPLORATORY: Environmentally Friendly Formation of Self-Assembled Monolayers and Surface-Initiated Polymer Films in Carbon DioxideThis collaborative research will investigate the use of environmentally benign carbon dioxide (CO2) as a solvent in the formation of self-assembled monolayers (SAMs) and ultrathin polymer films grown by a surface-initiated process. Due to its small molecular size and weak interaction with metal surfaces such as gold, CO2 is a nearly ideal solvent to promote the formation of densely packed, highly crystalline SAMs, as recently reported by the authors of this project. Further research will examine the formation of SAMs onto gold from partially fluorinated alkanethiols and the effect of co-solvent on the structure and barrier properties of monolayer films. This research also seeks to correlate for the first time the surface-averaged structure and barrier properties of SAMs as obtained by reflectance-absorption infrared spectroscopy (RAIRS) and electrochemical impedance spectroscopy (EIS), respectively, with their microscopic properties such as domain size and defect content as determined by scanning probe microscopy (SPM). This research will also develop a new class of surface-initiated, living polymer films based on the synthetic process of polyhomologation. The films are initiated from a boron-terminated SAM and have the interesting property that the terminal groups of the polymer film can be selected to create a wide variety of surface compositions. During the growth of these films, the precursor molecules must diffuse through the growing film and react at the active boron site so that solvents that enhance the transport of the precursor through the film will increase the rate of film growth and the ultimate thickness of the films. Carbon dioxide is a potentially effective solvent for enhancing the growth of these novel polymer films due to its ability to swell many polymers, its low viscosity and zero surface tension, and the high diffusion rates of many small molecules in CO2. In addition, the use of CO2 in this polymerization process enables a much simpler one-pot synthetic procedure in contrast to the use of organic solvents that must be conducted with numerous solvent transfers in a dry box. To date, there has been no previous investigation of the use of CO2 in the formation of surface-initiated polymer films and only one other study involving the formation of SAMs in CO2. The successful completion of this project will provide new strategies for forming these technologically important ultrathin films through environmentally friendly processing. Furthermore, this project should enhance the knowledge base for materials processing in CO2 and facilitate the increased use of CO2 in research and industry.