NER: Supercritical Carbon Dioxide Extraction Process for Forming Nanoporous Materials for Low-k and Biosensor Applications

具有可控纳米孔结构的材料将在微电子和生物传感器领域得到潜在的应用。我们的目标是将用于创建纳米相分离材料的纳米模板方法与其中一个相的超临界二氧化碳萃取相结合。所提出的方法相对于现有技术的进步包括在可使用的基质材料类型上增加的灵活性，以及与通过热降解从基质中去除致孔剂的方法相比的处理优势。这项拟议工作的科学挑战在于理解与提取二氧化碳可溶成分有关的聚合物物理，而不会使基质崩溃。本质上，这与玻璃化转变、塑化效应、基质的粘弹性性质以及抽出引起的应力有关。我们将在德克萨斯理工大学准备旋转膜，并与IBM的合作者合作，准备纳米相分离的形态。这些薄膜将含有一种不溶于超临界二氧化碳的成分，也将含有一种可以提取的可溶性成分。对薄膜在超临界CO2萃取前后的性能进行表征，包括测量薄膜的介电性能、厚度和折射率。此外，还将用傅里叶变换红外光谱、透射电子显微镜和原子力显微镜对薄膜进行研究。两名研究生和一名本科生研究人员将在私人投资促进机构的直接监督下进行研究。

Materials with controlled nanoporous structures will be developed for potential applications in the areas of microelectronics and biosensors. The goal is to couple a nanotemplating methodology for creating nanophase separated materials with supercritical CO2 extraction of one of the phases. The advancement of the proposed methodology over the current state of the art includes increased flexibility in the types of matrix materials which can be used, as well as processing advantages over methods in which the porogen is removed from the matrix by thermal degradation. The scientific challenge of the proposed work lies in understanding the polymer physics associated with extraction of the CO2 soluble component without collapse of the matrix. In essence, this is related to the glass transition, plasticization effects, the viscoelastic properties of the matrix and the stresses incurred due to extraction. We will prepare spin-on films at Texas Tech, as well as working with collaborators at IBM, to prepare nanophase separated morphologies. The films will contain a component which is insoluble in supercritical CO2 and will also contain a soluble component which can be extracted. Characterization of the properties of the films before and after exposure to supercritical CO2 extraction will be performed, including measurement of the dielectric properties, thickness and refractive index. In addition, films will be studied by Fourier transform infrared spectrometry, transmission electron microscopy and atomic force microscopy. Two graduate students and one undergraduate researcher will perform the research under the direct supervision of the PIs.