Synthesis of armchair graphene nanoribbons from the 10,10′-dibromo-9,9′-bianthracene molecules on Ag(111): the role of organometallic intermediates.
- 1 Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden. .
- 2 MAX IV Laboratory, Lund University, Box 118, 22100, Lund, Sweden. .
- 3 V.A. Fock Institute of Physics, St. Petersburg State University, 198504, St. Petersburg, Russia. .
- 4 MAX IV Laboratory, Lund University, Box 118, 22100, Lund, Sweden.
- 5 V.A. Fock Institute of Physics, St. Petersburg State University, 198504, St. Petersburg, Russia.
- 6 School of Physical Sciences, Dublin City University, Dublin, D09, Ireland.
- 7 School of Physics, Trinity College Dublin, College Green, Dublin, D02, Ireland.
- 8 Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan.
- 9 Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba, 305-0044, Japan.
- 10 Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden.
- 11 MAX IV Laboratory, Lund University, Box 118, 22100, Lund, Sweden. .
We investigate the bottom-up growth of N = 7 armchair graphene nanoribbons (7-AGNRs) from the 10,10′-dibromo-9,9′-bianthracene (DBBA) molecules on Ag(111) with the focus on the role of the organometallic (OM) intermediates. It is demonstrated that DBBA molecules on Ag(111) are partially debrominated at room temperature and lose all bromine atoms at elevated temperatures. Similar to DBBA on Cu(111), debrominated molecules form OM chains on Ag(111). Nevertheless, in contrast with the Cu(111) substrate, formation of polyanthracene chains from OM intermediates via an Ullmann-type reaction is feasible on Ag(111). Cleavage of C-Ag bonds occurs before the thermal threshold for the surface-catalyzed activation of C-H bonds on Ag(111) is reached, while on Cu(111) activation of C-H bonds occurs in parallel with the cleavage of the stronger C-Cu bonds. Consequently, while OM intermediates obstruct the Ullmann reaction between DBBA molecules on the Cu(111) substrate, they are required for the formation of polyanthracene chains on Ag(111). If the Ullmann-type reaction on Ag(111) is inhibited, heating of the OM chains produces nanographenes instead. Heating of the polyanthracene chains produces 7-AGNRs, while heating of nanographenes causes the formation of the disordered structures with the possible admixture of short GNRs.
Electrospinning of food-grade nanofibres from whey protein.
- 1 Department of Food and Nutritional Science, University of Reading, Whiteknights, RG6 6AP, UK.
- 2 Department of Chemistry, University of Reading, Whiteknights, RG6 6AD, UK. Electronic address: .
- 3 CoSAXS beamline, MAX IV Laboratory, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden.
- 4 Centre for Rapid and Sustainable Product Development, Rua de Portugal – Zona Industrial, 2430-028 Marinha Grande, Portugal.
- 5 Department of Chemistry, University of Reading, Whiteknights, RG6 6AD, UK.
In this study, electrospinning has been employed to produce micro to nano scale fibres of whey protein in order to investigate their potential for use in the food industry. Initially, spinning of pure whey protein proved challenging; so in order to facilitate the spinning of freshly prepared aqueous solutions, small amounts of polyethylene oxide (as low as 1% w/w in solution) were incorporated in the spinning solutions. The electrospun composite polyethylene-oxide/whey fibres exhibited diameters in the region of 100 to 400 nm, showing the potential to build fibre bundles from this size up. Time-dependent examinations of pure whey protein aqueous solutions were conducted using rheometery and small angle neutron scattering techniques, with the results showing a substantial change in the solution properties with time and stirring; and allowing the production of fibres, albeit with large diameters, without the need for an additive. The spinability is related to the potential of the whey protein composites to form aggregate structures, either through hydration and interaction with neighbouring proteins, or through interaction with the polyethylene oxide.