Influence of microstructural variations on morphology and separation properties of polybutadiene-based polyurethanes

Polybutadiene-based polyurethanes with different cis/trans/1, 2-vinyl microstructure contents are synthesized. The phase morphology and physical properties of the polymers are investigated using spectroscopic analysis (FTIR and Raman), differential scanning calorimetry (DSC), X-ray scattering (WAXD and SAXS) and atomic force microscopy (AFM). In addition, their gas transport properties are determined for different gases at 4 bar and 25 °C. Thermodynamic incompatibility and steric hindrance of pendant groups are the dominant factors affecting the morphology and properties of the PUs. FTIR spectra, DSC, and SAXS analysis reveal a higher extent of phase mixing in high vinyl-content PUs. Moreover, the SAXS analysis and AFM phase images indicate smaller microdomains by increasing the vinyl content. Smaller permeable soft domains as well as the lower phase separation of the PUs with higher vinyl content create more tortuous pathways for gas molecules and deteriorate the gas permeability of the membranes

Graphene oxide-fullerene nanocomposite laminates for efficient hydrogen purification

Graphene oxide (GO) with its unique two-dimensional structure offers an emerging platform for designing advanced gas separation membranes that allow for highly selective transport of hydrogen molecules. Nevertheless, further tuning of the interlayer spacing of GO laminates and its effect on membrane separation efficiency remains to be explored. Here, positively charged fullerene C₆₀ derivatives are electrostatically bonded to the surface of GO sheets in order to manipulate the interlayer spacing between GO nanolaminates. The as-prepared GO-C₆₀ membranes have a high H₂ permeance of 3370 GPU (gas permeance units) and an H₂/CO₂ selectivity of 59. The gas separation selectivity is almost twice that of flat GO membranes because of the role of fullerene

Efficient 3‐Hydroxybutyrate Production by Quiescent Escherichia coli Microbial Cell Factories is Facilitated by Indole‐Induced Proteomic and Metabolomic Changes

The authors show that quiescent (Q‐Cell) Escherichia coli cultures can maintain metabolic activity in the absence of growth for up to 24 h, leading to four times greater specific productivity of a model metabolite, 3‐hydroxybutyrate (3HB), than a control. Q‐cells can be created by using the proton ionophore indole to halt cell division of an hns mutant strain. This uncouples metabolism from cell growth and allows for more efficient use of carbon feedstocks because less metabolic effort is diverted to surplus biomass production. However, the reason for the increased productivity of cells in the quiescent state was previously unknown. In this study, proteome expression patterns between wild‐type and Q‐cell cultures show that Q‐cells overexpress stress response proteins, which prime them to tolerate the metabolic imbalances incurred through indole addition. Metabolomic data reveal the accumulation of acetyl‐coenzyme A and phosphoenolpyruvate: excellent starting points for high‐value chemical production. We demonstrate the exploitation of these accumulated metabolites by engineering a simple pathway for 3HB production from acetyl‐coenzyme A. Quiescent cultures produced half the cell biomass of control cultures lacking indole, but were still able to produce 39.4 g L−1 of 3HB compared to 18.6 g L−1 in the control. Q‐cells therefore have great potential as a platform technology for the efficient production of a wide range of commodity and high value chemicals

Adaptable Ultraviolet Refl ecting Polymeric Multilayer Coatings of High Refractive Index Contrast

A synthetic route is demonstrated to build purely polymeric nanostructured multilayer coatings, adaptable to arbitrary surfaces, and capable of effi ciently blocking by refl ection a targeted and tunable ultraviolet (UV) range. Refl ection properties are determined by optical interference between UV light beams refl ected at the interfaces between polystyrene layers of different porosity and hence refractive index. As no dopant absorber intervenes in the shielding effect, polymer degradation effects are prevented. Alternated porosity results from the modulation of photochemical effects at the few tens of nanometers length scale, combined with the collective osmotic shock induced during the processing of the precursor diblock copolymer fi lm. Experimental evidence of the application of this method to coat rough surfaces with smooth and conformal UV protecting fi lms is providedEuropean Union’s Seventh Framework Programme 307081Ministerio de Economía y Competitividad MAT2011-2359

Oriented Two-Dimensional Porous Organic Cage Crystals

The formation of two-dimensional (2D) oriented porous organic cage crystals (consisting of imine-based tetrahedral molecules) on various substrates (such as silicon wafers and glass) by solution-processing is reported. Insight into the crystallinity, preferred orientation, and cage crystal growth was obtained by experimental and computational techniques. For the first time, structural defects in porous molecular materials were observed directly and the defect concentration could be correlated with crystal growth rate. These oriented crystals suggest potential for future applications, such as solution-processable molecular crystalline 2D membranes for molecular separations

<講演7>「孔」をエネルギー・環境・医療に役立てる

日時・場所: 2018年3月17日(土)10:00-17:10 : おかやま未来ホール; 主催: 京都大学、京都大学研究連携基盤, 後援: 岡山県教育委員会、読売新聞

Novel methodology for facile fabrication of nanofiltration membranes based on nucleophilic nature of polydopamine

Novel methodology for facilely fabricating nanofiltration (NF) composite membrane has been successfully developed by employing nucleophilic nature of polydopamine (PDA) chemistry. The self-polymerized PDA coating over polysulfone (PSf) substrate was utilized as a key intermediate layer for trimesoyl chloride (TMC) grafting followed by poly(ethyleneimine) (PEI) deposition to construct the hierarchically structured separation layer of NF membrane. In contrast to the electrophilic quinone moieties of PDA layer usually involved in the Michael addition and Schiff base reactions with polymeric amines for membrane preparation in previous reports, the phenolic hydroxyl groups of catechol moieties as well as amine groups at the PDA layer possess nucleophilic nature, which are capable of quickly coupling with the highly reactive acyl chlorides to form ester and amide bonds in the step of TMC grafting, resulting in TMC moieties covalently anchored at the PDA layer with free acyl chloride groups. Such created acyl chlorides are further coupled with the amine groups of branched PEI polymer in the PEI deposition procedure to form the stable amide bonds linking the PDA base layer and PEI upper layer in the resulting hierarchical separation layer. The properties of membranes prepared at different stages were characterized with respect to surface chemistry, pore properties, and separation performances to understand deeply the newly developed methodology for membrane preparation. Further studies focusing on NF properties and stability of the developed NF membrane revealed that such membrane shows high efficiencies in retention of divalent cations, small organic molecules as well as heavy metal ions, and exhibits desirable thermal stability and long-term performance stability. 2016 Elsevier B.V.This work is supported by Grant from the Qatar National Research Fund (QNRF) under its National Priorities Research Program (NPRP) award number NPRP 4-935-2-354 . The statements made herein are solely the responsibility of the authors. We acknowledge Gas Processing Center (GPC, Qatar University) for XPS measurements and Center of Advanced Materials (CAM, Qatar University) for AFM measurements.Scopu