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to 40% conversion can be achieved with almost complete selectivity to methane and energy consumption of 1.55 Gcal/ mol (F. Sastre, A. Corma, H. García; J. Am. Chem. Soc., 2012, 134, 14137) (Scheme 5).
of CO. Using H2
both reagents can undergo photolysis, and H2
0.67% at 14 h). For the irradiation of CO2 using H2
competing process accompanying the formation of CO and CH4
generation from water is a (CO2
(K+
with total selectivity toward CH4 energy consumption of 4.5 Gcal/mol.
can increase CO2 GO PTA
O as reducing agent, basic solids -exchanged Y zeolite or hydrotalcites) conversion up to 2.21% and an
When CO2 irradiation is carried out in the gas phase in the presence of H2
O, conversion gas as reducing agent, up
This result opens a door in the quest for efficient photocatalysts that could further increase the apparent quantum yield of the process, particularly at longer wavelengths.
Gels for all seasons Thermosensitive nanogels based on highly crosslinked polyionic liquids (CLPNs) are available in one step by the copolymerisation of imidazolium (ImIL)-based monomers with cross-linkers in selective solvents (Y. Xiong, J. Liu, Y. Wang, H. Wang, R. Wang; Angew. Chem. Int. Ed., 2012, 51, 9114) (Scheme 6). The ImIL-based CLPNs are thermosensitive and display reversible, temperature-driven nanogel–macrogel transitions in methanol. ImIL-based
with epoxides, and could be readily separated by filtration, because of their thermosensitive properties. Such attributes make them a robust material platform suitable for a wide range of applications.
CLPNs were also found to be effective catalysts for CO2
Graphene printing
Scientists in China have developed a method to produce large-scale, high quality, graphene composite films easily and cheaply (H. Zhang, A. Xie , Y. Shen, L. Qiu, X. Tian; Phys. Chem. Chem. Phys., 2012, 14, 12757) (Scheme 7). Graphene oxide (GO) nanosheets and polyoxometalate, such as H3
(PTA), are prepared into a multilayer film via a layer-by-layer using an standard inkjet printer. The GO/PTA composite thin film shows linear, uniform and regular layer-by-layer growth. Under UV irradiation, a photoreduction reaction takes place in the film, which converts GO to reduced GO (rGO) due to the photoreduction activity of polyoxometalate clusters. The process could be invaluable
PW12 UV irradiation
Scheme 7 Scheme 8
in commercialising the material for electrochemical biosensor applications.
Joining the unjoinable Researchers at Kiel University in Germany have now developed the first technology which is capable of joining silicone and Teflon, two so-called ‘unjoinable’ materials (X. Jin, J. Strueben, L. Heepe, A. Kovalev, Y.K. Mishra, R. Adelung, S.N. Gorb, A. Staubitz; Advanced Materials, doi: 10.1002/adma201201780) (Scheme 8).
The technology utilises passive nano- scaled zinc oxide crystal linkers, shaped like tetrapods, in which four legs protrude from the point of origin, as internal staples. During the joining process, the zinc oxide crystals are sprinkled evenly onto a heated layer of Teflon. Then, a layer of silicone is poured on top. In order to join the materials firmly, they are then heated to 100°C for less than an hour causing the nano tetrapods in between the polymer layers to pierce the materials, sinking into them and becoming anchored. The shape of the tetrapod means that
pulling the tetrapod on one arm from a polymer layer, causes the remaining three arms to dig in deeper and to hold on even firmer. With the tetrapod staples, a
Chemistry&Industry • November 2012 53 O40 cycloaddition reactions
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