Supported polysilsesquioxane membrane and production thereof

Membranes of the invention comprise a hybrid silica film on a organic polymer support. The silica comprises organic bridging groups bound to two or more silicon atoms, in particular at least 1 of said organic bridging groups per 10 silicon atoms. The membranes can be produced by dry chemistry processes, in particular plasma-enhanced vapour deposition of bridged silane precursors, or by wet chemistry involving hydrolysis of the bridged silane precursors. The membranes are inexpensive and efficient for separation of small molecules and filtration processes

Amino-functionalized microporous hybrid silica membranes

The present study describes the effect of the incorporation of amino-functionalized terminating groups on the behaviour and performance of an organic–inorganic hybrid silica membrane. A primary amine, a mixed primary and secondary amine, and an imidazole functionality were selected. The molar ratio of the amino-functionalized precursors in the matrix forming 1,2-bis(triethoxysilyl)ethane (BTESE) precursor was varied in the range of 25–100 mol%. Strong water adsorption, which remains at temperatures up to 523 K, was found for all membranes. The observed low gas permeances and contrasting high water fluxes in pervaporation were explained in relation to the strong water adsorption. XPS measurements indicate a relation between the concentration of amino functional groups in the hybrid layers and the starting amine concentration of the sols. XPS measurements also revealed the existence of a maximum loading of the amino-functionalized precursor. Depending on the precursor, a maximum N/Si element ratio between 0.07 and 0.45 was found. At amine concentrations higher than a precursor dependent threshold value, membrane selectivity is constant over the range of amine concentrations. For alcohol/water (95/5 wt%) feed mixtures, the observed water concentrations in the permeate were over 90 wt% for EtOH and 95 wt% for n-BuOH dehydratio

Crystal and Magnetic Structures of Ca4Mn3O10, an n = 3 Ruddlesden-Popper Compound

The crystal and magnetic structures of the n = 3 Ruddlesden-Popper phase with the ideal composition Ca4Mn3O10 have been studied using X-ray and neutron powder diffraction. The crystal structure at 293 K is relatively insensitive to the partial pressure of oxygen used in sample preparation. A sample prepared in air showed an orthorhombic distortion (space group Pbca, a = 5.26557(12), b = 5.26039(11), c = 26.8276(5) �) from the ideal n = 3 RP structure, as did a sample prepared under 800 atm of O2 pressure (a = 5.26005(4), b = 5.25569(4), c = 26.83543(20) �). Both samples showed a magnetic phase transition at 115 K from a paramagnetic phase with extensive short-range spin ordering to a weakly ferromagnetic (μferro = 2 � 10-3 μB per Mn) low-temperature phase. The antiferromagnetic components of the atomic magnetic moments (2.23(2) μB per Mn) order in a G-type manner within each perovskite block, and the interblock coupling reflects the orthorhombic symmetry of the structure

Hybrid ceramic nanosieves: Stabilizing nanopores with organic links

Unprecedented hydrothermal stability in functional membranes has been obtained with hybrid organic-inorganic nanoporous materials, enabling long-term application in energy-efficient molecular separation, including dehydration up to at least 150 °C

Hydrothermally stable molecular separation membranes from organically linked silica

A highly hydrothermally stable microporous network material has been developed that can be applied in energy-efficient molecular sieving. The material was synthesized by employing organically bridged monomers in acid-catalysed sol-gel hydrolysis and condensation, and is composed of covalently bonded organic and inorganic moieties. Due to its hybrid nature, it withstands higher temperatures than organic polymers and exhibits high solvolytical and acid stability. A thin film membrane that was prepared with the hybrid material was found to be stable in the dehydration of n-butanol at 150 °C for almost two years. This membrane is the first that combines a high resistance against water at elevated temperatures with a high separation factor and permeance. It therefore has high potential for energy-efficient molecular separation under industrial conditions, including the dehydration of organic solvents. The organically bridged monomers induce increased toughness in the thin film layer. This suppresses hydrolysis of Si-O-Si network bonds and results in a high resistance towards stress-induced cracking. The large non-hydrolysable units thus remain well incorporated in the surrounding matrix such that the material combines high (pore) structural and mechanical stability. The sol mean particle size was found to be a viable parameter to tune the thickness of the membrane layer and thus optimize the separation performance. We anticipate that other hybrid organosilicas can be made in a similar fashion, to yield a whole new class of materials with superior molecular sieving properties and high hydrothermal stability