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

The origins of regio- and stereoselectivity in the ring-opening metathesis polymerization of 3-substituted cis-cyclooctenes by monoaryloxide pyrrolide imido alkylidene (MAP) Mo- and W-based catalysts are determined at the M06-2X/SDD|6-311+G(2df,p)//M06-L/SDD|6-31G(d)|MIDI! level of density functional theory. Considering cis-cyclooctene (COE) and 3-methyl-cis-cyclooctene (3MCOE) as monomers and W(N-t-Bu)(CH-t-Bu)(OHMT)(Pyr) (OHMT = hexamethylterphenoxide, Pyr = pyrrolide) as a catalyst, all possible syn and anti combinations of alkylidene and cyclic olefin, relative to the imido ligand, are evaluated. The observed Z-selectivity for the ring-opening metathesis (ROM) of COE is due to the large size of the aryloxide ligand, which forces both the alkylidene and the incoming cyclic olefin to be syn relative to the imido ligand. As determined previously for Grubbs’ second-generation catalyst (G2), breakdown of the metallacyclobutane intermediate is the rate-limiting step for cyclic olefins having ring sizes exce...

Factors Controlling Selectivity in the Ring-Opening Metathesis Polymerization of 3-Substituted Cyclooctenes by Monoaryloxide Pyrrolide Imido Alkylidene (MAP) Catalysts

Thin film luminescent solar concentrators are promising components of distributed power generation systems for building integrated photovoltaic applications. However, thin film geometries require high luminophore loading fractions to achieve sufficient absorption of sunlight, which, in the case of nanocrystal luminophores, can lead to aggregation and light scattering. In this work, we integrate CdSe/CdS nanocrystals into thin films of poly(cyclohexylethylene) at a range of loading fractions and characterize the composites with a combination of spectroscopic and simulation tools. We find that increased incident sunlight scattering is observed for the increasing luminophore loading fraction, but that the scattering is mostly limited to higher energy sunlight such that visible transmittance and haze of the samples are all greater than 89.7% and less than 8.3%, respectively. We then analyze the refractive index of the composite and show that the increase in loading fraction also affects the propagation of photoluminescence in the film, especially if the refractive index of the film is greater than that of the substrate. These studies show the importance of understanding the optical transport within thin films and provide design criteria to fabricate thin films for future implementation into building integrated photovoltaic applications.

CdSe/CdS–poly(cyclohexylethylene) thin film luminescent solar concentrators

The copolymerization of both high- and low-strain cyclic olefins employing three ruthenium-based metathesis catalysts is desribed. The effect of the ligand environment as well as the nature of the carbene on the copolymerizations is discussed.

Ring‐opening metathesis copolymerization employing ruthenium‐based metathesis catalysts

The invention described herein provides a novel lactide monomer derivative and process for preparing the lactide monomer derivative. The monomer derivative of the invention is bifunctional in nature, and can be employed a variety of efficient synthesis processes to prepare various polymers. Further, the bifunctional monomer derivative can be used to prepare various intermediate-stage compounds and polymers, which in turn can be used to synthesize other compounds, polymers, copolymers and composites. The lactide monomer derivative has a bifunctional norbornene spiro lactide structure, spiro[6-methyl-1,4-dioxane-2,5-dione-3,2′-bicyclo[2.2.1]hept[5]ene], and structure as follows: 
and stereoisomers thereof. The lactide monomer derivative is bifunctional in that either 1) the norbornene ring, 2) lactide ring, or 3) both, can be opened and used in polymer synthesis for the backbone or the reactive branch for other polymeric syntheses.

Bifunctional lactide monomer derivative and polymers and materials prepared using the same

A lamellar forming poly(styrene-stat-glycidyl methacrylate)-block-polylactide, P(S-s-GMA)-b-PLA, diblock polymer containing the photoacid generator 4-iodophenyldiphenylsulfonium triflate (IST) was ...

Temporally Controlled Curing of Block Polymers in the Disordered State Using Thermally Stable Photoacid Generators for the Preparation of Nanoporous Membranes

Marc A. Hillmyer

Papers

Factors Controlling Selectivity in the Ring-Opening Metathesis Polymerization of 3-Substituted Cyclooctenes by Monoaryloxide Pyrrolide Imido Alkylidene (MAP) Catalysts

CdSe/CdS–poly(cyclohexylethylene) thin film luminescent solar concentrators

Ring‐opening metathesis copolymerization employing ruthenium‐based metathesis catalysts

Bifunctional lactide monomer derivative and polymers and materials prepared using the same

Temporally Controlled Curing of Block Polymers in the Disordered State Using Thermally Stable Photoacid Generators for the Preparation of Nanoporous Membranes