Dendrimer intercalation in layered double hydroxides
Dendrimer intercalation in layered double hydroxides
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DOI：
10.1007/s10934-009-9306-3
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发表时间：
2010-08
影响因子：
2.6
通讯作者：
Márcio José dos Reis;V. Prevot;F. Leroux;F. Silvério;J. Valim
中科院分区：
文献类型：
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作者：
Márcio José dos Reis;V. Prevot;F. Leroux;F. Silvério;J. Valim
基于层状双氢氧化物（LDH）与聚酰胺胺树枝状大分子（PAMAM，代数-0.5和代数+0.5）的新型有机/无机（O/I）杂化组装体通过两种不同的路线使用在恒定pH下的直接共沉淀或在双表面活性剂S+S−相中的阴离子交换程序来制备。所获得的材料，其特征在于通过粉末X射线衍射，热重分析与质谱，傅里叶变换红外光谱。O/I LDH组装体的X射线粉末衍射图显示了LDH基材料的特征轮廓，其基底间距取决于树枝状聚合物的性质。事实上，对于两种合成方法，交错的PAMAM-0.5产生了与主体结构层垂直的分子排列一致的层间空间。对于PAMAM+0.5，考虑到其球形尺寸，观察到小得多的基底间距。这一观察结果被解释为分子收缩以适应层间LDH间隙，这是由于PAMAM−0.5内的键角扭曲而成为可能。FTIR光谱证实了在Zn 2Al/PAMAM G−0.5和Zn 2Al/PAMAM G+0.5组装体中存在两个部分。最后，与质谱相关的热分析证实了这种组成，并且原位温度XRD数据表明+0.5代的高度约束排列并没有伴随着热结构稳定性的提高;事实上，由PAMAM-0.5制备的组装体更稳定。两种O/I PAMAM LDH组装体构成了明确定义的材料，其是催化应用的候选者。
New organic/inorganic (O/I) hybrid assemblies based on Layered Double Hydroxide (LDH) with polyamide amine dendrimer (PAMAM, generation −0.5 and generation +0.5) were prepared by two different routes using either the direct coprecipitation at constant pH or the anion exchange procedure in double surfactant S+S−phases. The obtained materials were characterized by means of powder X-ray diffraction, thermal gravimetric analysis associated with mass spectrometry, and Fourier-transform infrared spectroscopy. X-ray powder diffraction pattern of the O/I LDH assembly exhibit characteristic profiles of LDH-based materials with basal spacing depending on the nature of the dendrimer. Indeed, for both synthetic procedures, interleaved PAMAM −0.5 gives rise to an interlayer space in agreement with a perpendicular molecular arrangement against the layer of the host structure. For PAMAM+0.5, considering its spherical dimension, a much smaller basal spacing was observed. This observation was interpreted as shrinkage of the molecule to accommodate the interlayer LDH gap, which was rendered possible by the bond angle twisting within PAMAM−0.5. FTIR spectra confirm the presence of both moieties inside both Zn2Al/PAMAM G−0.5 and Zn2Al/PAMAM G+0.5 assemblies. Finally, thermal analysis associated with mass spectrometry confirm this composition, and in situ temperature XRD data reveal that the highly constrained arrangement for the generation +0.5 is not accompanied by a gain in thermal structural stability; in fact, the assembly prepared from PAMAM −0.5 is more stable. Both O/I PAMAM LDH assemblies constitute well-defined materials which are candidate for catalytic applications.