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

该项目研究了一种新型的聚合物接枝膜，这种膜具有改善气体分离特性的潜力，在环境、能源和化学制造领域的广泛应用。聚合物接枝膜由无机纳米颗粒与接枝聚合物配体组成的基质组成，与常用的有机膜相比表现出更好的分离特性。该项目将结合理论分析、合成和实验评估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理的基本了解。该项目还将提供教育和推广部分，包括为佛罗里达农工大学(一所历史上的黑人学院或大学)的本科生提供研究机会。尽管一类关键的有机膜是由玻璃聚合物制成的，但它们的渗透性(即产品通量)和选择性(即所需物种的纯度)呈负相关。使用化学接枝聚合物链的无机纳米颗粒(NPs)组装的初步工作表明，这些材料在这方面提供了意想不到的优势。基于模拟，推测聚合物接枝纳米粒子自组装成有序阵列时会产生“间隙空间”，只有通过拉伸一些接枝链才能填充这些间隙空间(“熵挫败”)。放置溶质分子可以缓解这种挫折感，并提高分离能力。这项研究是基于这样一个假设，即非球形纳米粒子可能由于填充到由空位(约10%)稳定的亚晶中而提供分离优势。非球形NP接枝聚合物的研究将通过以下两个方面进行：(1)开发新的理论设计工具，以找到优化相关气体混合物渗透性和选择性的NP形状和接枝参数；(2)合成接枝非球形NP的聚合物，将它们组装成膜，并使用一套包括先进的散射技术(X射线、中子)和理论相结合的工具来表征其多尺度结构和动力学。这应该允许验证设计结果，并有助于结束预测-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。除了与佛罗里达农工大学的教育合作外，调查人员还将招收代表性较低的学生(包括女性和少数族裔)，双重目标是让哥伦比亚大学的学生进入当地行业，并吸引行业参与者进入哥伦比亚大学的更高学位和/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.