Chain Growth Polycondensation via Substituent Effects for the Synthesis of Functional Rigid Rod Polymer Brushes

聚合物对表面的改性广泛应用于新技术的开发或现有技术的改进，从传感器到智能涂层。通过在表面物理吸附聚合物来进行涂层是一种更通用的方法，但它存在淋溶问题。在表面化学附着聚合物可以提供更坚固和更持久的涂层，但目前的合成技术限制了可以附着的聚合物的分子结构和体系结构。为了解决这个问题，科罗拉多矿业学院的博耶斯和维亚斯教授正在开发一种新的表面引发聚合技术，直接从各种不同的表面“生长”出具有所需结构和性能的聚合物。这种合成方法的一个潜在应用是制备用于从海水中去除盐分的新型膜。获得清洁饮用水是全球许多人面临的一个关键问题，从海水或咸水中去除盐分已成为向淡水资源有限的地区提供饮用水的一项重要技术。该项目还为研究生和本科生提供了研究机会。在这个项目中，研究小组致力于开发一种新的表面引发聚合技术，该技术基于取代基链生长缩聚机理(SECGP)，用于制备具有明确结构和性能的芳香聚合物刷子。该项目的具体目标是：1)设计和合成芳环上含有多种酯基、氨基和取代基的N-取代氨基苯甲酸酯单体；2)研究单体结构和聚合条件对反应动力学和所得芳香族聚酰胺性能(如相对分子质量和溶解度)的影响；3)进行密度泛函理论(DFT)计算，阐明单体结构的空间和电子效应对聚合机理和动力学的影响；4)在二氧化硅衬底上进行表面引发SECGP，研究表面性质对芳香聚合物刷子(包括嵌段共聚聚合物刷子)形成的影响，并探索这些新型聚合物刷子的结构-性能关系；5)在陶瓷膜上制备芳香族聚酰胺刷子，并测试其在海水淡化中的性能。一个潜在的应用是反渗透膜，这些新的刷子可以克服涂层不稳定性、生物污染和限制当前聚合物膜的通量容量降低的问题。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The modification of surfaces with polymers is widely used in the development of new technologies or the improvement of existing technologies, ranging from sensors to smart coatings. Coating by physically adsorbing polymers on surfaces is a more versatile approach, but it suffers from the issue of leaching. Chemically attaching polymers on surfaces provides more robust and longer lasting coatings, but current synthetic techniques limit the molecular structures and architectures of polymers that can be attached. To tackle this problem, Professors Boyes and Vyas of the Colorado School of Mines are developing a new surface-initiated polymerization technique for "growing" polymers of desired architectures and properties directly from a variety of different surfaces. A potential application of this synthetic methodology is the preparation of novel membranes for the removal of salt from seawater. Access to clean drinking water is a critical problem facing many people across the globe and the removal of salt from seawater or brackish water has become an important technique for providing drinking water to regions that suffer from limited sources of fresh water. This project also provides research opportunities to graduate and undergraduate students. In addition, outreach programs to local high schools are established to educate and stimulate the next generation of scientists and engineers.In this project, the research team focuses on developing a new surface-initiated polymerization technique based on the chain growth polycondensation via substituent effects mechanism (SECGP) for preparing aromatic polymer brushes with well-defined structures and properties. The specific objectives of the project are: 1) to design and synthesize N-substituted aminobenzoate monomers with a variety of ester leaving groups, amino groups, and substituents on the aromatic ring; 2) to investigate the effects of monomer structures and polymerization conditions on reaction kinetics and properties (such as molecular weight and solubility) of the resulting aromatic polyamides; 3) to perform density functional theory (DFT) calculations to elucidate the steric and electronic effects of the monomer structures on the polymerization mechanism and kinetics; 4) to conduct surface initiated SECGP on silica substrates, investigate the effect of surface properties on the formation of aromatic polymer brushes (including block copolymer brushes), and probe the structure-property relationships of these new polymer brushes; and 5) to prepare aromatic polyamide brushes on ceramic membranes and test their performance in water desalination. A potential application is in reverse osmosis membranes, where these new brushes can overcome issues with coating instability, biofouling, and reduced flux capacity that limit current polymer membranes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.