DMREF: Collaborative Research: Designing Optimal Nanoparticle Shapes and Ligand Parameters for Polymer-Grafted Nanoparticle Membranes

该项目研究了一类新的聚合物接枝膜，这些膜具有改善气体分离特性的潜力，适用于环境，能源和化学制造领域的广泛应用。 聚合物接枝膜由具有接枝聚合物配体的无机纳米颗粒基质组成，与常用的有机膜相比，其显示出改进的分离特性。 该项目将使用理论分析，合成和实验评估的组合来优化纳米颗粒的形状和聚合物的性能，同时提供对接枝结构提高分离效率的机制的基本理解。 该项目还将提供教育和推广的组成部分，包括研究机会，本科生从佛罗里达A M大学（一个历史上的黑人学院或大学）。 虽然一类关键的有机膜是由玻璃状聚合物制成的，但它们的渗透性（即，产物通量）和选择性（即，所需物质的纯度）是负相关的。使用无机纳米粒子（NPs）与聚合物链化学接枝的组件的初步工作表明，这些材料在这方面提供了意想不到的优势。基于模拟，假设聚合物接枝纳米颗粒自组装成有序阵列产生“间隙空间”，其只能通过拉伸一些接枝链来填充（“熵阻挫”）。放置溶质分子缓解了这种挫折，并产生了改善的分离能力。该研究是基于这样的假设，即非球形纳米颗粒可以提供分离优势，因为填充到由空位（10%的量级）稳定的亚晶体中。非球形NP接枝聚合物的研究将通过（1）开发新的理论设计工具，以找到NP形状和接枝参数，优化相关气体混合物的渗透性和选择性;以及（2）合成聚合物接枝的非球形NPs，将它们组装成膜，并使用包括先进散射技术在内的一套工具来表征它们的多尺度结构和动力学（X射线，中子）与理论相结合。这应该允许验证设计结果，并帮助关闭预测-合成-表征循环。这个经过验证的设计软件将免费提供给研究界。除了与佛罗里达A M大学的教育合作外，调查人员还将招募代表性不足的学生（包括女性和少数民族），其双重目标是将哥伦比亚大学的学生安置到当地行业，并吸引行业参与者进入哥伦比亚的更高学位和/或进修课程。

The project investigates a new class of polymer-grafted membranes that have the potential to improve gas separation characteristics for a wide range of applications in the environmental, energy, and chemical manufacturing areas. The polymer-grafted membranes consist of a matrix of inorganic nanoparticles with grafted polymer ligands that show improved separation characteristics compared to commonly used organic membranes. The project will use a combination of theoretical analysis, synthesis, and experimental evaluation to optimize both the nanoparticle shape and the polymer properties, while providing basic understanding of the mechanism by which the grafted structures improve separation efficiency. The project will also provide educational and outreach components including research opportunities for undergraduate students from Florida A&M University (a historically black college or university). While a key class of organic membranes is made of glassy polymers, they suffer from the fact that their permeability (i.e., product flux) and selectivity (i.e., purity of the desired species) are inversely correlated. Preliminary work using assemblies of inorganic nanoparticles (NPs) chemically grafted with polymer chains show that these materials offer unexpected advantages in this context. Based on simulations it is postulated that the self-assembly of the polymer grafted-NPs into ordered arrays creates "interstitial spaces" which can only be filled by stretching some of the grafted chains ("entropic frustration"). Placing solute molecules relieves this frustration and yields the improved separation ability. The study is predicated on the hypothesis that non-spherical nanoparticles may offer a separation advantage due to packing into meta-crystals that are stabilized by vacancies (of order 10%). Non-spherical NP-grafted polymers will be studied by (1) developing novel theoretical design tools to find the NP shapes and grafting parameters that optimize the permeability and selectivity of relevant gas mixtures; and (2) synthesizing polymer grafted non-spherical NPs, assembling them into membranes and characterizing their multi-scale structure and dynamics using a suite of tools including advanced scattering techniques (x-ray, neutron) coupled with theory. This should allow for the validation of the design results and help close the prediction-synthesis-characterization loop. This validated design software will be made freely available to the research community. In addition to the educational collaboration with Florida A&M University, the investigators will also recruit underrepresented students (both women and minorities) with the dual goals of placing Columbia University students into local industry and attracting industrial participants into higher degree and/or refresher programs at Columbia.