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

Thermoset materials containing ordered structures with ∼10-nm dimensions were prepared from a mixture of a low-molecular-weight poly(ethylene oxide)−poly(ethylene-alt-propylene) (PEO−PEP) diblock copolymer and a poly(Bisphenol-A-co-epichlorohydrin) epoxy resin that selectively mixes with the PEO block. The phase behavior of PEO−PEP/epoxy blends, with compositions spanning 10−93 wt % block copolymer, was investigated in the uncured state (without hardener) using small-angle X-ray scattering (SAXS) and dynamic mechanical spectroscopy. Without hardener, the phase behavior of block copolymer/epoxy blends was similar to model block copolymer/homopolymer blends and varied with changes in the blend composition and temperature. The following morphologies were observed with increasing epoxy concentration:  lamellar, cubic bicontinuous, hexagonally packed cylinders, body-centered cubic packed spheres, and disordered micelles. Methylene dianiline, an aromatic amine hardener, was added to the blends, and the real-tim...

Nanostructured Thermosets from Self-Assembled Amphiphilic Block Copolymer/Epoxy Resin Mixtures

Self-assembly and polymerization of epoxy resin-amphiphilic block copolymer nanocomposites

Polyolefins are macromolecular alkanes and include the most familiar and most commercially produced plastic, polyethylene. The low cost of these materials combined with their diverse and desirable property profiles drive such large-scale production. One property that renders polyolefins so attractive is their resistance to harsh chemical environments. However, this attribute becomes a severe limitation when attempting to chemically convert these plastics into value-added materials. Functionalization of polymers is a useful methodology for the generation of new materials with wide ranging applications, and this tutorial review describes both new and established methods for the post-polymerization modification of polyolefins.

Post-polymerization functionalization of polyolefins.

In the midst of this era of nanotechnology and shrinking device size, block copolymers have evolved from their use in traditional application areas (eg, adhesives, additives, and elastomers) to enable the development of materials for new emerging and more advanced technologies This review discusses the use of block copolymers to generate nanoporous polymers that can be used either directly, in applications such as membrane filtration, or subsequently as a template for the formation of other nanostructured materials The work within describes published research from the beginning of 2005 to the present discussing nanoporous materials in the context of: (i) nanolithography and new alignment technologies, (ii) monoliths, (iii) new fabrication techniques, and (iv) membranes A summary and perspective on the current direction of the stimulating area of block copolymer derived nanoporous materials concludes the review

Templating Nanoporous Polymers with Ordered Block Copolymers

Nanoporous membranes containing monodisperse pores of 24 nm diameter are fabricated using poly(styrene-b-lactide) block copolymers to template the pore structure. A 4 mum thin film of the block copolymer is cast onto a microporous membrane that provides mechanical reinforcement; by casting the copolymer film from the appropriate solvents and controlling the solvent evaporation rate, greater than 100 cm(2) of a thin film with polylactide cylinders oriented perpendicular to the thin dimension is produced. Exposing the composite membrane to a dilute aqueous base selectively etches the polylactide block, producing the porous structure. The ability of these pores to reject dissolved poly(ethylene oxide) molecules of varying molecular weight matches existing theories for transport through small pores.

Marc A. Hillmyer

Papers

Nanostructured Thermosets from Self-Assembled Amphiphilic Block Copolymer/Epoxy Resin Mixtures

Self-assembly and polymerization of epoxy resin-amphiphilic block copolymer nanocomposites

Post-polymerization functionalization of polyolefins.

Templating Nanoporous Polymers with Ordered Block Copolymers

Self-Assembled Block Copolymer Thin Films as Water Filtration Membranes