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In this work, we explore the kinetics of the photopolymerization-induced phase separation (photo-PIPS) process and the interplay of mechanisms controlling the development of the microstructure in a photosensitive resin comprised of pentaerythritol tetraacrylate (PETA) and 2-ethylhexyl methacrylate (2-EHMA) monomers with polypropylene glycol (PPG, M n = 4000 g/mol) linear polymer additive and diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) photoinitiator. We control the kinetics of photopolymerization by interrupting the irradiation at various stages of the process and varying the light intensity. Evolution of the microstructure is monitored by transmittance testing and scanning electron microscopy (SEM) inspection of fractured surfaces that are exposed to methanol for the purpose of removing the phase-separated PPG content. The evolution of the network is monitored by real-time Fourier-transform infrared (FTIR) spectroscopy during irradiation and intermittent probing after the cessation of irradiation. Three mechanisms controlling the evolution of the microstructure are identified: phase separation, photoinitiator consumption, and microstructural refinement. Phase separation begins immediately after the onset of network development and leads to a rapid reduction of transmittance due to the formation of PPG-rich subdomains. Microstructural refinement takes place at later stages leading to a reduction of these subdomains, a gradual increase of the PPG concentration within subdomains and an associated increase of transmittance. TPO consumption takes place during irradiation and accounts, to a smaller extent, for the recovery of the transmittance. Interrupting the irradiation allows generation of materials with various degrees of conversion and sizes of phase-separated subdomains, which provides a new way to control material properties. [Display omitted] • Photo-PIPS is studied in a system composed from PETA, 2-EHMA and PPG. • Phase separation and microstructural refinement control microstructure development. • Transmittance decreases due to phase separation. • Subsequently, transmittance increases due to refinement and volume reduction. [ABSTRACT FROM AUTHOR]

A novel aryl bromine bearing polymer was synthesized by Friedel-Crafts polycondensation. This precursor polymer substrate was used for C–N coupling via Buchwald-Hartwig amination to incorporate 9 examples of aryl amines into the polymer chains with high conversions (80–100%). Two aminated polymers were subsequently quaternized to give anion conducting polymers. These quaternary ammonium polymers show promising electrochemical membrane property because of their ability to transport mobile anions through the material while being electrically insulating. Membrane characteristics crucial to high electrochemical performance including ion exchange capacity, anion conductivity, water uptake, swelling ratio, and alkaline stability were evaluated. Image 1 [ABSTRACT FROM AUTHOR]

In this work we develop thermoset materials with heterogeneous microstructures on sub-micron scales by photopolymerization-induced phase separation (photo-PIPS). To this end, we designed a photo-curable resin based on pentaerythritol tetraacrylate (PETA), an acrylate monomer, combined with 2-ethylhexyl methacrylate (2-EHMA), a methacrylate diluent. Polypropylene glycol (PPG) was used as a phase separation agent. Phase separation was monitored by reactive light transmittance using a custom-built light transmission apparatus and through dynamic mechanical analysis (DMA). The photopolymerization kinetics and the microstructure morphology were characterized using real-time Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. We observe double phase separation: PETA and 2-EHMA separate due to different reactivities, while PPG phase separates as the network develops due to immiscibility. A synergy is observed between the two processes: PPG phase separation leads to an enhanced separation of 2-EHMA. Phase separation leads to reduced transmittance due to scattering, which is primarily associated with the separation of 2-EHMA. Phase separation also causes the reduction of stiffness due to the formation of PPG subdomains. The kinetics is enhanced by increasing the PPG molecular weight and increasing the irradiation intensity. [Display omitted] • Photo-PIPS is studied in a system composed from PETA, 2-EHMA and PPG. • Both 2-EHMA and PPG phase separate. • Separation of 2-EHMA is enhanced as the PPG molecular weight increases. • Reduced transmittance is observed as phases separate. • The material stiffness decreases due to PPG phase separation. [ABSTRACT FROM AUTHOR]

Abstract: The carbonyl groups of diaryl ketones and diaryl diketones were directly fluorinated with bis(2-methoxyethyl)aminosulfur trifluoride (Deoxofluor) under neat conditions to give the corresponding gem-difluorides and tetrafluorinated derivatives in moderate to high yields. [Copyright &y& Elsevier]

Abstract: Novel cisplatin analogs dichloro[4,4′-bis(4,4,4-trifluorobutyl)-2,2′-bipyridine]platinum (1) and fac-tricarbonylchloro[4,4′-bis(4,4,4-trifluorobutyl)-2,2′-bipyridine]rhenium (3) were synthesized and evaluated for their cytotoxicity. While 3 was not cytotoxic, 1 was 14 to 125 times more lethal than cisplatin in breast, prostate, and lung cancer cell lines. Compound 1 was able to induce apoptosis and the presence of the platinum atom was essential to its function as a cytotoxin. [Copyright &y& Elsevier]

Ionomers, which are used as polymer electrolyte membranes as well as catalyst binders in membrane electrode assemblies, are a key component of electrochemical energy conversion and storage technologies such as fuel cells, electrolyzers, and flow batteries. The use of ionomers in these clean energy technologies has a long history and there has been considerable progress in developing low-cost, high-performance ionomers in recent years. In this review article, we discuss some highlights from recent developments of ionomers with emphasis on chemically stable, mechanically durable, high-performance hydrocarbon ionomers and their state-of-the-art performance in electrochemical energy conversion devices. Future directions of ionomer research that are important to enhance our understanding and the remaining challenges related to device level applications are addressed. Image 1 • Roles of ionomers in electrochemical energy conversion technologies • Review highlights from recent developments of ionomers • Design strategies for high-performance ionomers • Future directions of ionomer research [ABSTRACT FROM AUTHOR]

In this study, we demonstrate a new class of poly(terphenylene) based anion exchange membranes (AEMs) with improved chemical stability and anion conductivity in vanadium redox flow batteries (VRFBs). A series of terphenyl- and biphenyl-based polymers with pendant quaternary ammonium alkyl groups were synthesized and characterized for VRFB applications. When the arrangement of the polymer backbone and cation-tethered alkyl chains was varied, the prepared AEM membranes exhibited extremely low vanadium permeance while maintaining high conductivity. These properties further provided a high coulombic efficiency close to 100% at all current densities as well as high voltage efficiency. The single cell VRFB performance with the poly(terphenylene) based AEMs showed 2–5% higher coulombic efficiency than those of commercial AEMs and similar voltage efficiency to those of commercial PEMs (Nafion® 212). The highest EE value of 93.64% was achieved at the current density of 20 mA/cm2 (vs. 72% EE for Nafion212). In addition, poly(terphenylene) based AEMs showed superior cycle stability and high capacity retention, thus demonstrating their high performance as promising IEMs for VRFB application. Image 1 • Synthesis of terphenyl-based AEMs with pendant quaternary ammonium alkyl groups. • Ion selectivity of the AEMs outperformed Nafion by 28 times. • The highest EE value of 93.64% was achieved at the current density of 20 mA/cm2. • VRFB testing for 150 cycles showed a highly stable and slow capacity decay. [ABSTRACT FROM AUTHOR]

Fluorinated polymers exhibit unique gas separation properties. However, the effect of the degree of fluorination in polymers on gas transport properties has not been elucidated. Herein, the alkenyl groups in the polybutadiene (PB) block of polystyrene- b -polybutadiene- b -polystyrene (SBS) were modified with gem -difluorocyclopropanation via difluorocarbene (∶CF 2). The F content in the fluorinated PB (FPB) phase ranges from 0 to 27 wt%, which was confirmed using 1H NMR spectroscopy, and physical properties of the polymers were determined, including density, fractional free volume (FFV), and glass transition temperature (T g). The Maxwell and additive models are used to estimate gas permeability and solubility in the FPB phase, respectively. Increasing the F content from 0 to 27 wt% in the FPB phase increases the CO 2 solubility from 0.58 to 1.1 cm3 (STP)/cm3 atm and CO 2 /C 2 H 6 solubility selectivity from 0.45 to 1.1 at 35 °C, suggesting that the F groups have induced favorable interaction with CO 2 and unfavorable interaction with C 2 H 6 in these partially fluorinated polymers. However, a further increase of the F content in the perfluoropolymer (such as polytetrafluoroethylene) decreases CO 2 solubility and CO 2 /gas solubility selectivity, indicating the unique CO 2 /gas separation properties in partially fluorinated polymers. The introduction of the F groups to the polymer also increases T g and decreases FFV and gas diffusivity, which can be satisfactorily described using a free volume model. Image 1 • Polybutadiene phase in SBS is systematically fluorinated via difluorocarbene. • CO 2 solubility in polymers increases with increasing F content before decreasing. • C 2 H 6 solubility in polymers decreases with increasing F content. • Partial fluorination may be better than perfluorination for CO 2 /gas separation. [ABSTRACT FROM AUTHOR]