Design and Optimization of Non-Fluorous CO2-Philic Polymers: FTIR and Phase Behavior Investigations

二氧化碳在化学加工中的应用继续引起人们的极大兴趣，因为二氧化碳通常比传统有机溶剂造成的危害更小。一度，人们认为二氧化碳可以简单地取代许多有机溶剂，但随后的研究表明，二氧化碳是一种相当弱的溶剂，因此需要不切实际的高压来溶解感兴趣的化合物。20世纪90年代“亲二氧化碳”的发现突然使许多应用在技术上成为可能，极大地提高了人们对二氧化碳作为溶剂的兴趣。这些新的亲二氧化碳试剂，主要是含氟聚合物，允许二氧化碳的许多新应用，从非均相聚合到均相催化。尽管氟化两亲体在技术上是成功的，但其高成本使得该工艺的经济效益不利，除非ihCO2-philelo能够以高于99%的效率回收。更复杂的是，从高压过程中回收添加剂既不容易也不便宜。使用含氟前体所固有的缺点极大地阻碍了大多数二氧化碳新应用的商业化，因此，基于二氧化碳的技术的全部前景尚未实现。PI研究了不含氟的亲二氧化碳试剂的设计。到目前为止，他已经使用了一套简单的启发式设计了三种类型的不含氟的亲二氧化碳试剂；他预计最终会发现其他的，这将大大扩大二氧化碳作为溶剂的适用性。如果我们继续合成和测试所有可能有用的结构，那么可能的设计变量（共聚物组成和拓扑结构）的数量将创建一个不切实际的大程序。此外，传统的热力学模型无法预测所有可能排列的行为。因此，PI将在匹兹堡大学和奥本大学之间开展一个协调项目，其最终目标是充分了解成分和拓扑结构对二氧化碳中新亲二氧化碳分子相行为的影响。他将结合目标合成，选定热物理性质的测量，高压FT-IR，以及从第一性原理开发精确的势函数，以数学方式描述他的材料与二氧化碳混合的热力学。成功将使他能够在数值上优化非氟亲二氧化碳试剂的结构。这里所描述的项目包括匹兹堡大学（E.J. Beckman， R.M. Enick, j.k Johnson）和奥本大学（C.B. Roberts）的一个完全整合的项目。在奥本大学（C.B. Roberts）进行的任务包括相行为和FTIR研究，其中高压红外测量将用于评估二氧化碳与纳入我们模型聚合物的刘易斯碱基的特定相互作用的强度。高压红外工作为合成设计和二氧化碳-聚合物相互作用的精确电位模型的构建提供了输入。

The application of CO2 to chemical processing continues to elicit significant interest, as CO2 generally poses fewer hazards than conventional organic solvents. At one time it was thought that CO2 could simply replace many organic solvents, but subsequent work showed that CO2 is a rather feeble solvent, and hence unrealistically high pressures are needed to dissolve compounds of interest. The discovery during the 1990's of "CO2-philes" suddenly rendered a number of applications technically possible, greatly raising interest in CO2 as a solvent. These new CO2-philes, primarily fluoropolymers, allowed a host of new applications for CO2, from heterogeneous polymerization to homogeneous catalysis. Although fluorinated amphiphiles were technically successful, their high cost renders the economics of a process unfavorable unless the ihCO2-philelo can be recycled at greater than 99% efficiency. Complicating matters further, recycle of additives from a high-pressure process is neither easy nor inexpensive. The drawbacks inherent to the useof fluorinated precursors have greatly inhibited the commercialization of most new applications for CO2, and thus the full promise of CO2-based technology has yet to be realized. The PI has investigated the design of non-fluorous CO2-philes. To date, he has used a set of simple heuristics to design three types of non-fluorous CO2- phile; he expects that others will ultimately be found, greatly broadening the applicability of CO2 as a solvent.The number of possible design variables (copolymer composition and topology) creates an impractically large program if we continue to synthesize and test all potentially useful structures. Further, conventional thermodynamic models are incapable of predicting the behavior of all of the possible permutations. Consequently, The PI will conduct a coordinated program between the University of Pittsburgh and Auburn University whose ultimate aim is to fully understand the effect of composition and topology on the phase behavior of our new CO2-philes in carbon dioxide. He will to combine targeted synthesis, measurement of selected thermophysical properties, high pressure FT-IR, and development of an accurate potential function from first principles to mathematically describe the thermodynamics of mixing of his materials with CO2. Success will allow himto numerically optimize the structure of non-fluorous CO2-philes.The program described herein involves a fully integrated project at both the University of Pittsburgh (E.J. Beckman, R.M. Enick, J.K. Johnson) and Auburn University (C.B. Roberts). The tasks to be performed at Auburn University (C.B. Roberts) include both phase behavior and FTIR studies, where high pressure IR measurements will be employed to evaluate the strength of specific interactions of CO2 with the Lewis base groups incorporated into our model polymers. The high pressure IR work provides both input to the synthetic design and the construction of an accurate potential model for CO2-polymer interactions.