Browsing by Author "Thordarson, P"
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- ItemGram-scale production of graphene based on solvothermal synthesis and sonication.(Nature Publishing Group, 2009-01) Choucair, M; Thordarson, P; Stride, JACarbon nanostructures have emerged as likely candidates for a wide range of applications, driving research into novel synthetic techniques to produce nanotubes, graphene and other carbon-based materials. Single sheets of pristine graphene have been isolated from bulk graphite in small amounts by micromechanical cleavage(1), and larger amounts of chemically modified graphene sheets have been produced by a number of approaches(2-7). Both of these techniques make use of highly oriented pyrolitic graphite as a starting material and involve labour-intensive preparations. Here, we report the direct chemical synthesis of carbon nanosheets in gram-scale quantities in a bottom-up approach based on the common laboratory reagents ethanol and sodium, which are reacted to give an intermediate solid that is then pyrolized, yielding a fused array of graphene sheets that are dispersed by mild sonication. The ability to produce bulk graphene samples from nongraphitic precursors with a scalable, low-cost approach should take us a step closer to real-world applications of graphene. © 2009, Nature Publishing Group
- ItemSmall angle neutron scattering (SANS) studies on the structural evolution of pyromellitamide self-assembled gels(ACS Publications, 2014-10-31) Jamieson, SA; Tong, KWK; Hamilton, WA; He, L; James, M; Thordarson, PThe kinetics of aggregation of two pyromellitamide gelators, tetrabutyl- (C4) and tetrahexyl-pyromellitamide (C6), in deuterated cyclohexane has been investigated by small angle neutron scattering (SANS) for up to 6 days. The purpose of this study was to improve our understanding of how self-assembled gels are formed. Short-term (< 3 h) time scales revealed multiple phases with the data for the tetrabutylpyromellitamide C4, indicating one-dimensional stacking and aggregation corresponding to a multifiber braided cluster arrangement that is about 35 Å in diameter. The corresponding tetrahexylpyromellitamide C6 data suggest that the C6 also forms one-dimensional stacks but that these aggregate to a thicker multifiber braided cluster that has a diameter of about 62 Å. Over a longer period of time, the radius, persistence length, and contour length all continue to increase in 6 days after cooling. These data suggest that structural changes in self-assembled gels occur over a period exceeding several days and that fairly subtle changes in the structure (e.g., tail-length) can influence the packing of molecules in self-assembled gels on the single-to-few fiber bundle stage © 2014, American Chemical Society.
- ItemSynthesis of per-deuterated alkyl amines for the preparation of deuterated organic pyromellitamide gelators(Pergamon-Elsevier Science Ltd, 2013-05-15) Yepuri, NR; Jamieson, SA; Darwish, TA; Rawal, A; Hook, JM; Thordarson, P; Holden, PJ; James, MA general, direct and scalable synthesis of per-deuterated alkyl amines is reported, together with their incorporation into pyromellitamides, which form self-assembled gels in cyclohexane. The deuterium labelling of these gelators allows the study of the dynamic intermolecular interactions in these materials using solid-state 2H NMR spectroscopy.© 2013, Elsevier Ltd.
- ItemTuning hydrogels through metal-based gelation triggers(Royal Society of Chemistry, 2017-11-18) McEwen, H; Du, EY; Mata, JP; Thordarson, P; Martin, ADTwo N-terminal capped tripeptides have been synthesised and display remarkable versatility in their gelation behaviour. Here, gelation can be triggered through the addition of an acid, biologically relevant metal salts or cell culture media. The structural and mechanical properties of the resultant hydrogels are tuneable, with gelation triggered through sodium cations amplifying secondary structure organisation yet decreasing gel stiffness. The effect of gelation trigger on cell viability is evaluated, with substantial improvement in cell survival observed when gelation is triggered using metal salts or cell culture media. © 2017 The Royal Society of Chemistry