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991.
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Dr. Cher Hon Lau Dr. Xavier Mulet Dr. Kristina Konstas Dr. Cara M. Doherty Dr. Marc‐Antoine Sani Prof. Frances Separovic Dr. Matthew R. Hill Dr. Colin D. Wood 《Angewandte Chemie (International ed. in English)》2016,55(6):1998-2001
The loss of internal pores, a process known as physical aging, inhibits the long‐term use of the most promising gas‐separation polymers. Previously we reported that a porous aromatic framework (PAF‐1) could form a remarkable nanocomposite with gas‐separation polymers to stop aging. However, PAF‐1 synthesis is very onerous both from a reagent and reaction‐condition perspective, making it difficult to scale‐up. We now reveal a highly dispersible and scalable additive based on α,α′‐dichloro‐p‐xylene (p‐DCX), that inhibits aging more effectively, and crucially almost doubles gas‐transport selectivity. These synergistic effects are related to the intimately mixed nanocomposite that is formed though the high dispersibility of p‐DCX in the gas‐separation polymer. This reduces particle‐size effects and the internal free volume is almost unchanged over time. This study shows this inexpensive and scalable polymer additive delivers exceptional gas‐transport performance and selectivity. 相似文献
993.
Laura Cantu' Elena Del Favero Paola Brocca Mario Corti 《Advances in colloid and interface science》2014
We revisit the structural investigation we performed over the years on gangliosides, biological amphiphiles typically found in the cell membranes of the nervous system of mammalians. Their molecular features, a large and charged saccharidic headgroup connected to a sticky and extended ceramide double tail, strongly dictate their aggregation properties and place ganglioside aggregates at the borderline between the curved world and the flatland. All along we found that unexpected interesting behaviours were induced by the hierarchical propagation of such extreme monomer properties, from the aggregate scale to the mesoscopic phases. In fact, even small changes in the monomer geometry or hindrance result in dramatic aggregate reshaping, due to collective amplification. Surface packing optimization requires preferential mutual orientation of headgroups, giving rise to trapped solid-disordered configurations. The interplay between interparticle and intraparticle interactions gives rise to unexpected behaviours and counterintuitive phase's landscape. In situ modification of monomer properties, operated by enzymatic digestion of aggregated ganglioside headgroups, either causes collective rearrangement or is overwhelmed by collective trapping, depending on their surface density. This aspect is interesting as gangliosides are not evenly distributed in cell membranes, but only in the outer leaflet, where they p]articipate in rafts, functional microdomains enriched in special lipids including cholesterol. We recently found that ganglioside GM1 forces a preferential distribution of cholesterol, constituting a collective structural pair across the membrane. In summary, ganglioside assemblies, through cooperativity, reach a structural complexity comparable or even bigger and more adaptive than that of a protein. 相似文献
994.
Frontispiece: Bilayer Networks within a Hydrogel Shell: A Robust Chassis for Artificial Cells and a Platform for Membrane Studies 下载免费PDF全文
995.
It is a commonly accepted assumption that membrane fusion involves an hourglass-shaped local contact between two monolayers of opposing membranes, an intermediate structure called a stalk. The shape of the stalk is considered as an axisymmetrical figure of revolution in 3D space, with a planar geometry in the initial configuration. The total energy of the stalk is evaluated from the assumption that the stalk has a constant curvature. Its negative value due to the presence of spontaneous curvature promotes hemifusion. An extension of the original model developed in Markin and Albanesi [23] is proposed, in which any geometrical feature of the stalks can be expressed in explicit form, by considering the stalks as nodoid surfaces. The local stresses and induced internal moments due the membrane bending are evaluated based on the adopted parameterization. 相似文献
996.
Fabrication of highly ordered porous membranes of cellulose triacetate on ice substrates using breath figure method 下载免费PDF全文
Bing Yu Hailin Cong Zejing Li Hua Yuan Qiaohong Peng Ming Chi Shujing Yang Ruixia Yang S. Ranil Wickramasinghe Jianguo Tang 《Journal of Polymer Science.Polymer Physics》2015,53(8):552-558
Highly ordered porous membranes of cellulose triacetate (CTA) were prepared successfully on ice substrates using breath figure method. The pore size and structure of the membrane were modulated by changing CTA concentrations and substrate materials. As the CTA concentration in the casting solution increased, the pore size in the formed membrane decreased. The regularity of the membrane cast on the ice substrate was much better than that of the membrane cast on glass substrate, because the low temperature of ice substrate slowed down the evaporation rate of organic solvent, which offered enough time for condensed water droplets to self‐organize into an ordered array dispersed in the polymer solution before their coagulation. The ordered porous CTA membrane was not only used for microfiltration, but also used for fabrication of functional microstructures. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 552–558 相似文献
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998.
Erik J. Vriezekolk Eddy de Weerd Wiebe M. de Vos Kitty Nijmeijer 《Journal of Polymer Science.Polymer Physics》2014,52(23):1568-1579
Blends of self‐assembling polystyrene‐block‐poly(4‐vinyl pyridine) (PS‐b‐P4VP) diblock‐copolymers and poly(4‐vinyl pyridine) (P4VP) homopolymers were used to fabricate isoporous and nanoporous films. Block copolymers (BCP) self‐assembled into a structure where the minority component forms very uniform cylinders, while homopolymers, resided in the core of the cylinders. Selective removal of the homopolymers by ethanol immersion led to the formation of well‐ordered pores. In films without added homopolymer, just immersion in ethanol and subsequent swelling of the P4VP blocks was found to be sufficient to create pores. Pore sizes were tuned between 10 and 50 nm by simply varying the homopolymer content and the molecular weight of the block‐copolymer. Uniformity was lost when the average pore size exceeded 30 nm because of macrophase separation. However, preparation of films from low MW diblock copolymers showed that it is possible to have excellent pore size control and a high porosity, while retaining a low pore size distribution. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1568–1579 相似文献
999.
Masamichi Nishihara Liana Christiani Aleksandar Staykov Kazunari Sasaki 《Journal of Polymer Science.Polymer Physics》2014,52(4):293-298
The nanostructure of sulfonated polyimide (SPI)/dihydroxynaphthalene (DHN) derivative charge‐transfer (CT) complex hybrid films, which are noble alternative polymer electrolyte membranes (PEMs), is determined by a combined visible spectroscopy/quantum mechanical approach. From the visible spectra of SPI/2,6‐dihydroxynaphthalene (2,6‐DHN) and 1,5‐dihydroxynaphthalene (1,5‐DHN) CT complex hybrid films, it is confirmed that these films have different maximum wavelength, although difference of the molecular structure is small. From the calculation based on the experimental result, SPI and DHNs form multiple interactions consisting of not only CT interaction, but also hydrogen bonding in multilayered structures. CT interaction between SPI and DHN defines the DHN position in the SPI matrix, with DHN sitting in the cavity formed between SPIs. The molecular structure of the CT films derived from the multiple and complex interactions can recognize small differences in the structural isomers and bring changes of the optical property. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 293–298 相似文献
1000.