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Schematic representation of the self‐assembly of the oleanolic acid (OA) – Pb²⁺ complex under bidentate bridging mode.
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British 19th century painters formulated gelled systems often described as ideal paint mediums. These so-called megilps or gumtions are based on common paint materials like linseed oil, lead acetate, and mastic resin, and allowed painters such as J.M.W Turner to improve their paint's properties and achieve unprecedented effects in an age of innovat...
Citations
... In addition, he continues building new bridges with other fields, for example, by revisiting the chemical origins of "old" hybrid materials used in art. 17 In his nearly 45 years of career, Cleḿent Sanchez has had deep impact and exerted a huge influence on the Materials Chemistry community, through the development of a new axis of original research in hybrid materials, combining creativity and chemical intuition with the application of transversal stateof-the-art characterization techniques and in situ analysis, to ultimately gain insight in the delicate steps that lead to bioinspired nanomaterials. He has built solid bridges between local molecular structure and multiscale properties in complex hybrid nanoarchitectures. ...
... For A1 and A2 particles, a crossover towards a lower slope around q − 2 is observed around 0.03 Å − 1 for A2 and 0.07 Å − 1 for A1. This indicates a scattering by slightly aggregated randomly oriented platelets with a high aspect ratio (Duijneveldt et al., 2005;Hotton et al., 2021;Pasco et al., 2022), which agrees with the TEM observations. For the smallest size (A1), the beginning of a Guinier plateau is observed for q ≈ 1.5 10 − 3 Å − 1 . ...
... Despite the carboxylate features present in the jelly phase, it is interesting to note that these acetate compounds with Cu, Mn and Zn did not form homogenous gels. This investigation also indicates, that similar to the case with dammar-lead mixtures, the formation of soaps alone is not enough to form a gel; the gelation process requires the specific properties of lead (Pasco et al, 2021). ...
... Similar observations can be made with the formation of new carboxylate species in the system confirming the reaction between triterpenoids of the resin bearing acidic functions and the lead compound. These spectra are detailed inPasco et al. (2021) with details on the possible structure of the lead-oleanolic acid complex. ...
Gelled mediums were widely used during the nineteenth century, added to paint on the palette to modify its rheological, optical, and drying properties. Many variations of gelled mediums exist in the literature, all with the common basis of mastic resin or varnish, drying oil, and a lead compound. With the aim of unveiling the chemistry of such systems, reconstructions were carried out not only following the historical recipes, but in addition, exploring variations and simplifications to get a better understanding of the key ingredients and interactions inducing gelation. Different parameters were tested to establish whether these have an impact on the gelation mechanisms, particularly the influence of the nature and proportions of the ingredients and the preparation process. These reconstructions and their FTIR characterisation reveal the formation of metal-resin soaps, but also underline the specific role of lead in the gelation.
Among the functionalities exhibited by nanofibers, gelation/thixotropic properties arise from the solvent used. We clarified the selectivity of solvents for the gelation of nanofibers formed by diamide-based thixotropic additive molecules with two hydrocarbon chains. Chiral thixotropic additive molecules that form helical nanofibers tended to gel more efficiently in the same solvent compared to achiral straight nanofibers. These diamide groups with two hydrocarbon chains did not develop gelation ability in non-polar normal alkanes or solvents with low solubility owing to poor fiber development. In addition to that of the phenyl-based solvent, when the amount of the gelation solvent was increased, the entanglement density of the nanofibers decreased and consequently, the gelation ability tended to gradually decrease. These results support the conventional hypothesis, according to which the origin of solvent gelation is the efficient entrapment of solvent molecules into the tangled tissue of fibers.
