Postsynthesis stabilization of free-standing mesoporous silica films

Emulsion droplets as a dynamic interface for the direct and large-scale synthesis of ultrathin free-standing mesoporous silica films as well as 2D polymeric and carbon nanomaterials

The efficient synthesis of free-standing mesostructured two-dimensional (2D) nanofilms with high-yield as well as good control of composite, mesophase structure, orientation of the pore channel and thickness represents a big challenge. In this work, it was serendipitously found that microemulsion droplets of tetraethylorthosilicate (TEOS) could serve as a novel dynamic interface for continuous growth of nanofilms. Based on this finding, a general, efficient strategy for the direct and large-scale synthesis of free-standing mesoporous silica films (FSMSFs) was developed. Remarkably, with the careful control of the synthesis conditions, the FSMSFs with high-yield as well as good control of composite, mesophase structure, orientation of the pore channel and thickness could be efficiently achievable. More importantly, by using polymerizable surfactants the preorganized monomers in the nanochannels of the resultant silica films could be further converted into 2D polymers and carbon nanomaterials as well as metal particle-decorated forms, as exemplified by using pyrrole-terminated surfactants, demonstrating a powerful method to create 2D inorganic, organic or hybrid functional nanomaterials.

Ordered Porous Nanomaterials: The Merit of Small

This paper will introduce the reader to some of the “classical” and “new” families of ordered porous materials which have arisen throughout the past decades and/or years. From what is perhaps the best-known family of zeolites, which even now to this day is under constant research, to the exciting new family of hierarchical porous materials, the number of strategies, structures, porous textures, and potential applications grows with every passing day. We will attempt to put these new families into perspective from a synthetic and applied point of view in order to give the reader as broad a perspective as possible into these exciting materials.

Formation of mesostructured thin films at the air-liquid interface

The growth of free-standing surfactant-templated films of inorganic oxides at the air-solution interface is an attractive route to manufacture unsupported mesostructured membranes for a range of potential applications. So far this synthesis method has been relatively neglected due to the fragility of the initial films. More recent work to understand the mechanism of formation has led to development of thicker, more robust films, as well as providing new information on the general formation mechanisms of mesoporous materials whether in film or particulate form. This review describes the properties of silica and other inorganic oxide films templated by surfactants and grown at the air-solution interface, their formation mechanisms and implications for further development of these materials.

Targeted functionalization of nanoparticle thin films via capillary condensation

Capillary condensation, an often undesired natural phenomenon in nanoporous materials, was used advantageously as a universal functionalization strategy in nanoparticle thin films assembled layer-by-layer. Judicious choice of nanoparticle (and therefore pore) size allowed targeted capillary condensation of chemical vapors of both hydrophilic and hydrophobic molecules across film thickness. Heterostructured thin films with modulated refractive index profiles produced in this manner exhibited broadband antireflection properties with an average reflectance over the visible region of the spectrum of only 0.4%. Capillary condensation was also used to modify surface chemistry and surface energy. Photosensitive capillary-condensates were UV-cross-linked in situ. Undesired adventitious condensation of humidity could be avoided by condensation of hydrophobic materials such as poly(dimethyl siloxane).