Nanostructured bio-based castor oil organogels for the cleaning of artworks

New horizons on advanced nanoscale materials for Cultural Heritage conservation

“…64,70 As seen for the nanostructured cleaning fluids, research is currently focusing on the formulation of gels using bio-or natural compounds, which are being progressively adopted to design hydro-(for aqueous fluids) or organogels (able to load organic solvents). [71][72][73][74][75][76][77] Regarding the consolidation of works of art, nanoparticles of alkaline earth hydroxides constitute the first and main example of nanoscale materials designed for the restoration of murals, mortar, and stones. [78][79][80] Different synthetic approaches, such as top-down and bottom-up routes, have been adopted since the early 2000s to produce particles' dispersions in water or organic solvents.…”

“…In addition, they can replace hazardous and toxic substances detrimental for human health and harmful to the artefacts' original components. 52,71,72,76,[127][128][129][130][131] In this sense, biopolymer-based materials, such as natural resins and polysaccharides, 76,[131][132][133][134][135] are gaining growing interest. Other examples include biodegradable matrices obtained from waste products of supply chains, 136,137 as well as ''green'' surfactants and solvents.…”

New sustainable polymers and oligomers for Cultural Heritage conservation

“…Oligomers with moderate polydispersity were selected to validate the new protocol as a robust approach in the design of polymeric gels even on industrial scale. Then, the oligoesters were reacted with castor oil, a valuable renewable resource in chemical industry 47 but still almost unexplored in art conservation, 21,43,48 to yield a new class of organogels. In particular, the HLB evaluation protocol that we developed grants the possibility of introducing alternated domains with varying hydrophobicity/hydrophilicity in the castor oil polyurethane network, producing a completely new class of gels as compared to standard polymer networks with a homogeneous hydrophobic phase.…”

“…11 Castor oil, in particular, is a renewable resource that, being nonedible, does not impact on the food chain, and has large potential in the formulation of organogels for Cultural Heritage preservation or adhesives. 43,78 The following sections will be dedicated to the design of a new class of castor oil-oligoester organogels, reported in this contribution for the rst time.…”

From Nanoparticles to Gels: A Breakthrough in Art Conservation Science

“…124−126 While the pHEMA/PVP semi-IPNs and TC-PNs are being increasingly adopted as standards in cleaning interventions, new research efforts are now focusing on the design of "green" gel formulations based on biomaterials. 127 For instance, starch can partially replace PVA in the TC-PNs, 128 while castor oil 129 or polyhydroxybutyrate 130 has been recently used to build organogels, complementary tools to hydrogels when conservators wish to control the use of organic solvents rather than aqueous systems. Figure 6 shows an example where a castor oil-based organogel, loaded with a cleaning solvent, is used to selectively remove an aged varnish from a modern art masterpiece of metaphysical painting.…”