Morphological Properties of Methacrylate-Based Polymer Monoliths: From Gel Porosity to Macroscopic Inhomogeneities
Morphological Properties of Methacrylate-Based Polymer Monoliths: From Gel Porosity to Macroscopic Inhomogeneities
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DOI：
10.1021/acs.langmuir.7b00337
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发表时间：
2017-03-07
期刊：
影响因子：
3.9
通讯作者：
Tallarek, Ulrich
中科院分区：
文献类型：
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作者：
Muellner, Tibor;Zankel, Armin;Tallarek, Ulrich
将软硬物质材料的化学界面塑造成保证优异传输性能的物理形态，对于依赖于界面吸附、分离和反应的技术至关重要。例如，具有分层结构孔隙空间的聚合物单体广泛应用于流动驱动过程，其效率取决于支撑材料在几个长度尺度上的形态。与其他支撑结构相比，特别是与硅胶整体结构相比，聚合物整体结构的效率较低，这表明聚合物整体结构的形貌不理想。基于连续块面扫描电子显微镜的物理重建，我们评估了甲基丙烯酸酯基聚合物整体从孔隙尺度到柱尺度的结构特征。形态学数据显示，聚合物骨架为均匀的聚合物骨架，具有溶质不可穿透的核孔壳结构和非均匀的大孔空间，在近距离和跨柱尺度上存在不均匀性。尽管聚合物相的形态有利于有效的质量传递，但聚合物整体的性能受到大孔和大孔大小的严重跨柱梯度的限制。我们建议通过追求一种制备策略来克服这些形态学限制，这种制备策略涉及主动而不是被动塑造大孔空间，例如，通过使用二氧化硅单体作为聚合物单体制备的模板结构。
Shaping chemical interfaces of hard and soft matter materials into physical morphologies that guarantee excellent transport properties is of central importance for technologies relying on adsorption, separation, and reaction at the interface. Polymer monoliths with a hierarchically structured pore space, for example, are widely used in flow-driven processes, whose efficiency depends on the morphology of the support material over several length scales. Compared with alternative support structures, particularly silica monoliths, polymer monoliths yield lower efficiency, which suggests a suboptimal morphology. Based on physical reconstruction by serial block-face scanning electron microscopy we evaluate the structural features of a methacrylate-based polymer monolith from the pore scale to the column scale. The morphological data reveal a homogeneous polymer skeleton with a solute-impenetrable core porous shell architecture and a heterogeneous macropore space that suffers from inhomogeneities at the short-range and the transcolumn scale. Although the morphology of the polymer phase is favorable to efficient mass transport, the performance of the polymer monolith is limited by severe transcolumn gradients in macroporosity and macropore size. We propose to overcome these morphological limitations by pursuing a preparation strategy that involves active rather than passive shaping of the macropore space, for example, by using silica monoliths as templating structures for polymer monolith preparation.