Use of amphiphilic triblock copolymers to direct the organization of polymerizing silica species has resulted in the preparation of well-ordered hexagonal mesoporous silica structures (SBA-15) with uniform pore sizes up to approximately 300 angstroms. The SBA-15 materials are synthesized in acidic media to produce highly ordered, two-dimensional hexagonal (space group p6mm) silica-block copolymer mesophases. Calcination at 500°C gives porous structures with unusually large interlattice d spacings of 74.5 to 320 angstroms between the (100) planes, pore sizes from 46 to 300 angstroms, pore volume fractions up to 0.85, and silica wall thicknesses of 31 to 64 angstroms. SBA-15 can be readily prepared over a wide range of uniform pore sizes and pore wall thicknesses at low temperature (35° to 80°C), using a variety of poly(alkylene oxide) triblock copolymers and by the addition of cosolvent organic molecules. The block copolymer species can be recovered for reuse by solvent extraction with ethanol or removed by heating at 140°C for 3 hours, in both cases, yielding a product that is thermally stable in boiling water.

Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom pores

One of the most pervasive problems afflicting people throughout the world is inadequate access to clean water and sanitation. Problems with water are expected to grow worse in the coming decades, with water scarcity occurring globally, even in regions currently considered water-rich. Addressing these problems calls out for a tremendous amount of research to be conducted to identify robust new methods of purifying water at lower cost and with less energy, while at the same time minimizing the use of chemicals and impact on the environment. Here we highlight some of the science and technology being developed to improve the disinfection and decontamination of water, as well as efforts to increase water supplies through the safe re-use of wastewater and efficient desalination of sea and brackish water.

Science and technology for water purification in the coming decades

A family of highly ordered mesoporous (20−300 A) silica structures have been synthesized by the use of commercially available nonionic alkyl poly(ethylene oxide) (PEO) oligomeric surfactants and poly(alkylene oxide) block copolymers in acid media. Periodic arrangements of mescoscopically ordered pores with cubic Im3m, cubic Pm3m (or others), 3-d hexagonal (P63/mmc), 2-d hexagonal (p6mm), and lamellar (Lα) symmetries have been prepared. Under acidic conditions at room temperature, the nonionic oligomeric surfactants frequently form cubic or 3-d hexagonal mesoporous silica structures, while the nonionic triblock copolymers tend to form hexagonal (p6mm) mesoporous silica structures. A cubic mesoporous silica structure (SBA-11) with Pm3m diffraction symmetry has been synthesized in the presence of C16H33(OCH2CH2)10OH (C16EO10) surfactant species, while a 3-d hexagonal (P63/mmc) mesoporous silica structure (SBA-12) results when C18EO10 is used. Surfactants with short EO segments tend to form lamellar mesost...

Nonionic Triblock and Star Diblock Copolymer and Oligomeric Surfactant Syntheses of Highly Ordered, Hydrothermally Stable, Mesoporous Silica Structures

https://www.researchgate.net/file.PostFileLoader.html?id=526892a1d4c118a61d4360bd&assetKey=AS%3A272155479085058%401441898330516

Porosity of 3D biomaterial scaffolds and osteogenesis.

3.2.3. Hydroformylation 2467 3.2.4. Dimerization 2468 3.2.5. Oxidative Cleavage and Ozonolysis 2469 3.2.6. Metathesis 2470 4. Terpenes 2472 4.1. Pinene 2472 4.1.1. Isomerization: R-Pinene 2472 4.1.2. Epoxidation of R-Pinene 2475 4.1.3. Isomerization of R-Pinene Oxide 2477 4.1.4. Hydration of R-Pinene: R-Terpineol 2478 4.1.5. Dehydroisomerization 2479 4.2. Limonene 2480 4.2.1. Isomerization 2480 4.2.2. Epoxidation: Limonene Oxide 2480 4.2.3. Isomerization of Limonene Oxide 2481 4.2.4. Dehydroisomerization of Limonene and Terpenes To Produce Cymene 2481

Chemical Routes for the Transformation of Biomass into Chemicals

Solution-cast blends of lamellar-forming poly(styrene-stat-butadiene)-block-poly(lactide), P(S-s-B)-b-PLA, and peroxide were heated above their effective order–disorder transition temperature, TODT...

Bicontinuous Porous Nanomaterials from Block Polymers Radically Cured in the Disordered State for Size-Selective Membrane Applications

Efforts to create block-polymer-based templates with ultrasmall domain sizes has stimulated integrated experimental and theoretical work in an effort to design and prepare self-assembled systems th...

Synthesis, Simulation, and Self-Assembly of a Model Amphiphile To Push the Limits of Block Polymer Nanopatterning.

The aqueous self-assembly of μ-A(BC)n miktobrush terpolymers has been studied using dynamic light scattering and cryogenic transmission electron microscopy. In this system, the A block is hydrophilic poly(ethylene oxide), “O”, the B block is hydrophobic poly(methylcaprolactone), “C”, and the C block is hydrophobic and oleophobic poly(perfluoropropylene oxide), “F”. Two terpolymers were examined: one with an average of about two C blocks and two F blocks and another with an average of about three C blocks and two F blocks. In both cases, the total molar mass is near 40 kg mol–1, and the volume fraction of the single O block is greater than 50% of the whole. Both samples form multicompartment micelle structures with subdivided solvophobic cores of C and F domains. The morphologies observed are generally analogous to those previously observed for the self-assembly of μ-ABC miktoarm star terpolymers, namely, “raspberry” and “hamburger” micelles; however, an intriguing multicompartment polymersome morphology w...

Marc A. Hillmyer

Papers

Bicontinuous Porous Nanomaterials from Block Polymers Radically Cured in the Disordered State for Size-Selective Membrane Applications

Synthesis, Simulation, and Self-Assembly of a Model Amphiphile To Push the Limits of Block Polymer Nanopatterning.

Multicompartment Micelles by Aqueous Self-Assembly of μ-A(BC)n Miktobrush Terpolymers

Synthesis and characterization of hypercrosslinked, surface-confined, ultra-stable silica-based stationary phases.

Synthesis of Monodisperse α-Hydroxypoly(styrene) in Hydrocarbon Media Using a Functional Organolithium