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Oil-in-water synthesis of hollow-shell mesoporous peapod-like silicates: Electron microscopy insights
Microporous and Mesoporous Materials ( IF 5.2 ) Pub Date : 2018-01-09 , DOI: 10.1016/j.micromeso.2018.01.005
V. Morales , M. Pérez-Garnes , M. Balabasquer , J. González-Casablanca , R.A. García-Muñoz

Hollow mesoporous silica nanoparticles (HMSN) receive a remarkable attention for their many advantages in several applications. Hollow-shell mesoporous peapod-like silicates were synthesized based on the recently introduced drug structure-directing agent (DSDA) concept. The anionic DSDA was formed by the amidation of L-tryptophan with palmitoyl chloride. 3-Aminopropyltrimethoxysilane (APS) was employed as co-structure directing agent (CSDA). The interactions among DSDA, CSDA and silica source promoted the formation of the oil-in-water emulsions. We hypothesized that the emulsions aggregated in micelles that merged into sheet-like structures that curved, bent and closed to form spherical hollow structures. Finally, the hollow structures fused between them to form the final hollow-shell peapod-like silicates with 0.6–2.5 μm in length. Interestingly, the formation of inner lamellar-like mesoporous pillars separated by large mesovoids with sizes around 50 nm was promoted. The role of the APS is determinant in the synthesis of the hollow morphologies, since its absence disrupts the formation of HMSNs. The changes in the organic component packing and the charge density matching between the silica framework, continuously transforming, and the surfactant headgroups are postulated as the driving forces in determining the particles morphology. Moreover, based on an original TEM sample preparation, perpendicular views over the long axis, and mainly over the short axis were acquired, proving the symmetry of revolution of these materials along their axis. Perpendicular slices of the nanoparticles demonstrated the internal hollows and the inner crossing walls with lamellar-like mesoporosity. These materials are expected to have potential applications in fields including, batteries, adsorption, and mainly in biomedicine processes.



中文翻译:

中空介孔豆足状硅酸盐的水包油合成:电子显微镜的真知灼见

空心中孔二氧化硅纳米粒子(HMSN)在多种应用中具有许多优势,因此受到了极大的关注。基于最近引入的药物结构导向剂(DSDA)概念,合成了中空壳类豌豆状的中空硅酸盐。通过用棕榈酰氯酰胺化L-色氨酸形成阴离子DSDA。3-氨基丙基三甲氧基硅烷(APS)被用作共结构导向剂(CSDA)。DSDA,CSDA和二氧化硅源之间的相互作用促进了水包油型乳液的形成。我们假设乳液聚集在胶束中,并融合成弯曲,弯曲和闭合以形成球形空心结构的片状结构。最后,中空结构在它们之间融合,形成长度为0.6-2.5μm的最终中空壳豆荚状硅酸盐。有趣的是,促进了内部层状中孔柱的形成,该柱状柱被大小约50 nm的大中孔分开。APS的作用在空心形态的合成中起决定作用,因为它的缺失会破坏HMSN的形成。假定有机组分的堆积以及二氧化硅骨架之间的电荷密度匹配,连续转变和表面活性剂头基的变化是确定颗粒形态的驱动力。此外,基于原始的TEM样品制备,获得了长轴(主要是短轴)的垂直视图,证明了这些材料沿其轴的旋转对称性。纳米颗粒的垂直切片显示内部空心和内部横穿壁具有层状中孔。

更新日期:2018-01-09
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