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.

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Reduction of aqueous RhCl 3 with NaBH 4 in the presence of poly(vinyl pyrrolidone) (PVP) yields dense spherical nanostructures. The spherical aggregates, which generally have diameters between 10 and 100 nm, are built from smaller 1-3 nm Rh particles. The dense nanostructures are thermally stable beyond 100 °C, and they have a tendency to form ordered superstructures upon drying. Combining sodium n-dodecyl sulfate (SDS) with PVP modifies the size and morphology of the primary 1-3 nm particles, but does not change the spherical shape of the aggregates except at high concentrations of SDS. Smallangle X-ray scattering measurements show that the large aggregates are formed directly in solution from small Rh particles, consistent with TEM and AFM results. Magnetic measurements indicate that the Rh nanoparticle aggregates are Pauli paramagnetic.

TEM samples were prepared by dropping 10 lL of diluted solution in toluene onto 400-mesh carbon-coated copper grids by Finnpipette and slowly evaporating the solvent in air at room temperature. Many of these investigations have utilized ordered mesoporous silicas such as MCM-41 or SBA-15 as the inorganic component. These materials are in some regards ideally suited for this task, as they present the materials chemist with a highly ordered porous inorganic matrix, wherein well-developed silane chemistries can be exploited to build organic functionalities off the silica surface. In this vein there have been many investigations of the incorporation of organic functional groups into mesoporous silicas including the direct synthesis of hybrid materials, post-synthetic grafting, covalent versus non-covalent linkage, etc. [2,3,5] In general, a common theme of these investigations is that the organic moiety tethered to the surface is chemically ªsimpleº, often a single functional group. For hybrid materials to achieve their full potential the ability to synthesize complex/multifunctional organic moieties directly on the mesoporous substrate would be highly desirable.In the current report we describe the stepwise synthesis of a series of melamine-based dendrimers of various generations that are grown directly off the mesopore surface. While a few works have studied dendrimer±mesoporous silica hybrids formed via dendrimer physisorption, [6,7] and many works have studied the growth of dendrimers on nonporous silicas, [8±10] this is the first example we know of where complex organic macromolecules derived from multistep organic syntheses (e.g., six sequential reactions for the G3 (third-generation) dendrimer) have been grown using ordered mesoporous silica as a solid-phase support. As such we believe this work has important implications for organic±inorganic hybrid materials,

Multiple-quantum 1 H MAS NMR spectroscopy has been used to study defect sites in siliceous as-made ZSM-12 zeolite synthesized with perdeuterated benzyltrimethylammonium cations. The results of two-dimensional double-quantum and triple-quantum 1 H MAS NMR experiments show that three silanol (SiOH) protons of the defect site engage in hydrogen bonding with the charge-compensating siloxy (SiO -) group. Simulations of the double-quantum sideband pattern were used to determine an average dipolar coupling between the protons of 4.0 ((0.5) kHz (an equilateral triangular geometry is assumed). This value corresponds to a maximum distance of 3.1 ((0.1) Å, if the protons are rigid. We believe that these results have important implications concerning the nucleation mechanism of high-silica zeolites, as they provide new information on the structure of charge-compensating units in the zeolite colloidal precursors reported by others.

Utilizing polypeptide secondary structure as a means for controlling oxide pore architectures is explored. Poly-L-lysine is used as a model polypeptide as its folding behavior is well understood and compatible with the sol-gel chemistry of silica. Here, we show that silicas synthesized with poly-L-lysine in a R-helix conformation possess cylindrical pores that are approximately 1.5 nm in size, whereas silicas synthesized with poly-L-lysine in a β-sheet conformation possess larger pores, the size of which are a function of the poly-L-lysine concentration, or in other words the size of the aggregate. In both cases, highly porous materials are obtained. In-situ circular dichroism measurements of the synthesis mixtures show that the poly-L-lysine secondary structure is not perturbed during synthesis. Infrared spectroscopy of the as-synthesized materials is consistent with the poly-L-lysine retaining its secondary structure. Grand canonical Monte Carlo simulations were also performed to validate the interpretation of the experimental adsorption results. The experimental isotherms are consistent with simulated isotherms of cylindrical pores 1.3-1.7 nm in size, in good agreement with expected values. Our results suggest a new avenue for synthesizing porous oxides with highly tuneable pore sizes and shapes under mild conditions.

The synthesis of silica, silver bromide, and composite nanospheres made in the presence of block copolypeptide vesicles is reported. Hollow silica nanospheres of controllable size can be made with Lys:Phe 1:1 block copolypeptides, whereas at higher block ratios, uniform silica nanospheres are formed that are not hollow. Silver bromide nanospheres of controllable size in the range of 25−250 nm can also be formed, as well as silver bromide/silica core−shell particles. The silver bromide nanospheres can also be assembled into hollow rods in the presence of rhodamine 6G, and this process is reversible. The unique feature of this work is the ability to translate the information of an individual biomimetic supramolecular structure (e.g., vesicle) as a template into an inorganic material. The results show that block copolypeptides offer unique opportunities for assembling nanostructured materials.

Peptides capture CO2: Poly(L‐lysine) brush–mesoporous silica hybrids were prepared and evaluated as biomolecule‐based CO2 adsorbents using simulated flue gas (10 % CO2) and simulated ambient air (400 ppm CO2). Compared to representative amine‐based adsorbents, the hybrids show higher or comparable capture capacity and outperform other materials in terms of amine efficiency. The hybrids are suggested to be promising new materials for CO2 capture, especially, from ultra‐dilute gas streams.