Layer structure preservation during swelling, pillaring, and exfoliation of a zeolite precursor
Layer structure preservation during swelling, pillaring, and exfoliation of a zeolite precursor
复制标题
DOI：
10.1021/ja077711i
复制
发表时间：
2008-01-30
影响因子：
15
通讯作者：
Tsapatsis, Michael
中科院分区：
文献类型：
--
作者：
Maheshwari, Sudeep;Jordan, Edgar;Tsapatsis, Michael
MCM-22（P）是沸石MCM-22的前体，由可以溶胀和剥离以产生催化活性材料的层的堆叠组成。然而，目前的溶胀程序导致晶体形态沿着显著退化，同时结晶度部分丧失和结晶相溶解。用于分离、阻隔和其他应用的具有MCM-22的聚合物纳米复合材料和涂层的制造需要溶胀方法，该方法不显著改变晶体形态和层结构并且保持层的高纵横比。在这里，我们展示了这样一种方法，通过在室温下溶胀MCM-22（P）。低温工艺不会破坏母体MCM-22（P）材料中存在的骨架连接性。溶胀后的MCM-22（PS-RT）经水洗后形成了新的有序层状结构。有趣的是，溶胀过程是可逆的，并且溶胀的材料可以通过酸化样品恢复到MCM-22（P）。溶胀的材料也可以被柱撑以产生MCM-36类似物。它也可以被剥离，并且层可以被并入聚合物基质中以制造纳米复合材料。
MCM-22(P), the precursor to zeolite MCM-22, consists of stacks of layers that can be swollen and exfoliated to produce catalytically active materials. However, the current swelling procedures result in significant degradation of crystal morphology along with partial loss of crystallinity and dissolution of the crystalline phase. Fabrication of polymer nanocomposites and coatings with MCM-22 for separation, barrier, and other applications requires a swelling method that does not alter drastically the crystal morphology and layer structure and preserves the high aspect ratio of the layers. Here, we demonstrate such a method by swelling MCM-22(P) at room temperature. The low-temperature process does not disrupt the framework connectivity present in the parent MCM-22(P) material. By extensive washing with water, the swollen material, MCM-22(PS-RT), evolves to a new ordered layered structure. Interestingly, the swelling procedure is reversible and the swollen material can be restored back to MCM-22(P) by acidification of the sample. The swollen material can also be pillared to produce an MCM-36 analogue. It can also be exfoliated, and layers can be incorporated in a polymer matrix to make nanocomposites.