NIR‐sensitized cationic polymerization proceeded with good efficiency, as was demonstrated with epoxides, vinyl ether, and oxetane. A heptacyanine functioned as sensitizer while iodonium salt served as coinitiator. The anion adopts a special function in a series selected from fluorinated phosphates ( a : [PF 6 ] − , b : [PF 3 (C 2 F 5 ) 3 ] − , c : [PF 3 ( n ‐C 4 F 9 ) 3 ] − ), aluminates ( d : [Al(O‐ t ‐C 4 F 9 ) 4 ] − , e : [Al(O(C 3 F 6 )CH 3 ) 4 ] − ), and methide [C(O‐SO 2 CF 3 ) 3 ] − ( f ). Vinyl ether showed the best cationic polymerization efficiency followed by oxetanes and oxiranes. DFT calculations provided a rough pattern regarding the electrostatic potential of each anion where d showed a better reactivity than e and b . Formation of interpenetrating polymer networks (IPNs) using trimethylpropane triacrylate and epoxides proceeded in the case of NIR‐sensitized polymerization where anion d served as counter ion in the initiator system. No IPN was formed by UV‐LED initiation using the same monomers but thioxanthone/iodonium salt as photoinitiator. Exposure was carried out with new NIR‐LED devices emitting at either 805 or 870 nm.
Photoinitiated Polymerization of TPGDA was initiated with a NIR LED emitting at 790 nm using a redox based photoinitiator system comprising a cyanine as photosensitizer and a diaryl iodonium salt.
) were tested regarding their efficiency as radical initiator to initiate radical polymerization according to a sensitized mechanism. A NIR LED emitting at 790 nm was applied to initiate sensitized polymerization applying the polymethine S2265 as sensitizer. Change of the sensitizer resulting in spectral overlap with emission of UV-LED emitting at 395 nm complimented the experiments to understand the behavior of these iodonium salts under different exposure conditions. Furthermore, formation of protons was quantitatively probed by Rhodamine B lactone showing that UV sensitization resulted in a significant higher yield compared to NIR-sensitized photopolymerization. Surprisingly, the iodonium salt bearing the [(CF3SO2)3C] --anion exhibited a good performance in both radical photopolymerization and photoinduced formation of protons. Thioxanthon (ITX) served as sensitizer for all UV-LED experiments.
Engineering a life-support system for living on Mars requires the modeling of heat and mass transfer. This report describes the analysis of heat and mass transfer phenomena in a greenhouse dome, which is being designed as a pressurized life-support system for agricultural production on Mars. In this Martian greenhouse, solar energy will be converted into chemical energy in plant biomass. Agricultural products will be harvested for food and plant cultivation, and waste materials will be processed in a composting microbial ecosystem. Transpired water from plants will be condensed and recycled. In our thermal design and analysis for the Martian greenhouse, we addressed the question of whether temperature and pressure would be maintained in the appropriate range for humans as well as plants. Energy flow and material circulation should be controlled to provide an artificial ecological system on Mars. In our analysis, we assumed that the greenhouse would be maintained at a subatmospheric pressure under 1/3-G gravitational force with 1/2 solar light intensity on Earth. Convection of atmospheric gases will be induced inside the greenhouse, primarily by heating from sunlight. Microclimate (thermal and gas species structure) could be generated locally around plant bodies, which would affect gas transport. Potential effects of those environmental factors are discussed on the phenomena including plant growth and plant physiology and focusing on transport processes. Fire safety is a crucial issue and we evaluate its impact on the total gas pressure in the greenhouse dome.
Die NIR-sensibilisierte kationischeP olymerisation verläuft effizient mit Epoxiden, einem Vinylether und Oxetan mit einem Heptacyanin als Sensibilisator und Iodoniumsalz als Coinitiator.D as Anion wurde von fluorierten Phosphaten (a: [PF 6 ] À , b:[PF 3 (C 2 F 5 ) 3 ] À , c:[PF 3 (n-C 4 F 9 ) 3 ] À ), Aluminaten (d: [Al(O-t-C 4 F 9 ) 4 ] À , e:[ Al(O(C 3 F 6 )CH 3 ) 4 ] À )u nd einem Methid [C(O-SO 2 CF 3 ) 3 ] À (f)a usgewählt. Der Vinylether zeigte die beste Effizienz in der kationischen Polymerisation, gefolgt von Oxetanen und Oxiranen. DFT-Rechnungen ermçglichten eine Abschätzung des elektrostatischen Potentials fürj edes Anion, wobei d eine bessere Reaktivitäta ls e und b bewirkte.D ie Bildung interpenetrierender Polymernetzwerke (IPNs) erfolgte unter Verwendung von Trimethylolpropantriacrylat und Epoxiden im Fall einer NIR-sensibilisierten Polymerisation erfolgreich mit d als Gegenion fürd as Initiatorsystem. Keine IPN-Bildung wurdeb ei UV-LED-Initiierung unter Verwendung der gleichen Monomere mit Thioxanthon/Iodoniumsalz beobachtet. Die Belichtung wurde mit neuen NIR-LEDs durchgeführt, die bei 805 oder 870 nm emittieren.
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