Tailored Chain Sequences of Pendant Functional Groups and Resulting Phase Behavior of Gel-State Functionalized Blocky Copolymers

第1部分：非技术总和嵌段共聚物是一类独特的长链分子(聚合物)，由两条不同的链(段)在其一端连接在一起组成。如果这些块具有明显不同的化学性质，那么它们可能能够自组装成有序的物理结构，从而提供与单独块的性质非常不同且往往更好的材料性质。不幸的是，与仅合成一个嵌段的典型商品聚合物相比，化学合成嵌段共聚物通常要复杂得多，能源密集，成本也高得多。虽然聚合物化学家在开发合成嵌段共聚物的新方法方面取得了显著进展，但商业成功有限，往往局限于高成本领域的应用，如先进医疗设备或半导体制造。在这个项目中，将使用一种新的物理方法，通过选择性地修改商业可获得聚合物链上的特定单元序列，以直接、经济诱人的方式创建嵌段共聚物。这里的突破性方法涉及在凝胶状态下执行化学，即链的特定部分基本上对修饰化学隐藏。这项研究将在加快定制嵌段共聚物组件的创建方面取得重大进展，并增强对下一代膜技术的基础洞察力。考虑到我们社会面临的巨大挑战，该项目将提供成本效益高、容易获得的替代材料，以满足对净水膜、用于清洁能源转换的燃料电池膜以及医疗和保健行业的环境友好材料的关键需求。该项目研究活动的跨学科性质，从纯化学到材料结构和性质，将为渴望为我国在科学和技术先进的社会中的领导地位做出贡献的多样化的学生和研究人员社区提供大量的教育机会。第2部分：技术总结本项目将专注于一种新的方法，使用凝胶状态下的半结晶均聚物进行简单的后聚合化学反应来制造嵌段共聚物。由于只在半结晶网络中可访问的无定形链段上进行反应，这种新的物理过程产生了非随机的嵌段官能团，是传统用于合成嵌段共聚物的复杂聚合机制的简单替代。基于最近的发现，半结晶聚合物，如间规聚苯乙烯和聚醚醚酮，可以在非均相凝胶状态下进行溴化，作为一种创建具有定制序列分布的嵌段共聚物的简单方法，该项目旨在利用可与溴化芳香模板一起使用的丰富的取代化学来创建各种新的嵌段共聚物，作为一种系统地操纵相行为的手段，从而形成具有定制属性的有序形态。除了取代化学，半结晶凝胶的形态参数将通过控制温度、浓度和溶剂来精确地影响官能化和非官能化链段的顺序。这个项目要解决的重大挑战将是：我们现在是否可以通过调整这些新的凝胶态功能化的嵌段共聚体系的化学组成，来指导形成有序的相分离结构域，类似于传统的嵌段共聚聚合物？这种嵌段共聚物的膜将在建筑上量身定做，用于能源转换和水净化应用。该项目研究活动的跨学科性质，从纯化学到材料结构和性质，将有助于培养不同的研究人员群体，包括代表性不足的群体。教育推广活动将通过关注旨在确保更健康、更节能的全球社会的尖端研究来吸引所有年龄段的公民。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。

PART 1: NON-TECHNICAL SUMMARYBlock copolymers are a unique class of long chain molecules (polymers) that are made up of two different chains (blocks) attached together at one of their ends. If the blocks possess distinctly different chemical properties, then they may be capable of self-assembling into well-ordered physical structures that impart material properties that are very different, and often better, than the properties of the individual blocks alone. Unfortunately, the chemical synthesis of block copolymers is generally much more complicated, energy intensive, and expensive compared to that employed in synthesizing a typical commodity polymer of just one block. While polymer chemists have made remarkable progress in developing new ways to synthesize block copolymers, commercial success has been limited and often relegated to applications in high-cost fields such as advanced medical devices or semiconductor manufacture. In this project, a new physical approach will be used to create blocky copolymers in a straightforward, economically-attractive fashion by selectively modifying specific sequences of units along the chains of commercially available polymers. The breakthrough approach here involves performing chemistry in the gel state, whereby specific portions of the chains are essentially hidden from the modifying chemistry. This research will provide significant advancements in accelerating the creation of tailored block copolymer assemblies and enhance fundamental insight toward next-generation membrane technologies. With respect to the grand challenges facing our society, this project will provide cost-effective, readily available alternative materials needed to meet critical demands for water purification membranes, fuel cell membranes for clean energy conversion, and environmentally-friendly materials for the medical and healthcare industries. The interdisciplinary nature of research activities in this project, ranging from pure chemistry to materials structure and properties, will provide a plethora of educational opportunities to a diverse community of students and researchers eager to contribute to our nation's leadership in a scientifically and technologically advanced society.PART 2: TECHNICAL SUMMARYThis project will focus on a new way to create blocky copolymers using straightforward, post polymerization chemistries on semi-crystalline homopolymers in the gel state. With reactions upon only the accessible amorphous chain segments within the semi-crystalline network, this new physical process yields a non-random, blocky incorporation of functionality, and is a simple alternative to the complex polymerization mechanisms that are conventionally employed in the synthesis of block copolymers. Building upon recent discoveries that semi-crystalline polymers, such as syndiotactic polystyrene and poly(ether ether ketone), can be brominated in the heterogeneous gel-state as a simple way to create blocky copolymers with tailored sequence distributions, this project aims to engage a wealth of substitution chemistries available with brominated aromatic templates to create a wide variety of new blocky copolymers as a means to systematically manipulate phase behavior and thus the formation of ordered morphologies with tailored properties. In addition to the substitution chemistries, the morphological parameters of the semi-crystalline gel will be altered by controlled temperature, concentration, and solvent to precisely affect the sequences of functionalized and non-functionalized chain segments. The grand challenge to be addressed in this project will be: Can we now direct the formation of ordered phase-separated domains, similar to that observed with conventional block copolymers, by tailoring the chemical composition of these new, gel-state functionalized, blocky copolymer systems? Membranes of the blocky copolymers will be architecturally tailored for energy conversion and water purification applications. The interdisciplinary nature of research activities in this project, ranging from pure chemistry to materials structure and properties, will help to educate a diverse community of researchers, including underrepresented groups. Educational outreach activities will engage citizens of all ages through the focus on cutting-edge research aimed at ensuring a healthier, more energy-efficient global society.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.