Nanostructures & Spectroscopies
Dernières publications
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Ball-milling for efficient synthesis of pyridine-containing iron(ii) photosensitizers 
Auteur(s): Rastoder Enita, Michel T., Lamaty Frédéric, Bantreil Xavier
(Article) Publié:
Rsc Mechanochemistry, vol. 1 p.116 - 122 (2024)
Ref HAL: hal-04539390_v1
DOI: 10.1039/D3MR00033H
Exporter : BibTex | endNote
Résumé: Photoredox catalysis is becoming more and more prevalent in the 21st century as a new tool for organic and polymer synthesis. In addition, this domain clearly fits the expectations of the twelve principles of green chemistry. However, access to metal containing photosensitizers is not always straightforward and can require long reaction times, the use of toxic solvents and multi-step synthesis. These are definitely drawbacks that could be overcome with the use of novel technologies. In this report, we develop a one-pot two-step synthesis of iron(II) photosensitizers using ball-milling. Overall reaction times were drastically reduced, no solvent was needed during the reaction, and ten complexes could be isolated in high yields (73–99%). Using a transparent milling jar, the formation of the complexes could be followed using in situ Raman spectroscopy.
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Water-Driven Sol–Gel Transition in Native Cellulose/1-Ethyl-3-methylimidazolium Acetate Solutions
Auteur(s): Mohamed Yunus Roshan Akdar, Koch Marcus, Dieudonne-George P., Truzzolillo D., Colby Ralph, Parisi Daniele
(Article) Publié:
Acs Macro Letters, vol. 13 p.219-226 (2024)
Ref HAL: hal-04426657_v1
DOI: 10.1021/acsmacrolett.3c00710
Exporter : BibTex | endNote
Résumé: The addition of water to native cellulose/1-ethyl-3methylimidazolium acetate solutions catalyzes the formation of gels, where polymer chain-chain intermolecular associations act as cross-links. However, the relationship between water content (Wc), polymer concentration (Cp), and gel strength is still missing. This study provides the fundamentals to design water-induced gels. First, the sol-gel transition occurs exclusively in entangled solutions, while in unentangled ones, intramolecular associations hamper interchain cross-linking, preventing the gel formation. In entangled systems, the addition of water has a dual impact: at low water concentrations, the gel modulus is water-independent and controlled by entanglements. As water increases, more cross-links per chain than entanglements emerge, causing the modulus of the gel to scale as Gp ∼ C p^2 Wc^3.0±0.2. Immersing the solutions in water yields hydrogels with noncrystalline, aggregate-rich structures. Such water-ionic liquid exchange is examined via Raman, FTIR, and WAXS. Our findings provide avenues for designing biogels with desired rheological properties.
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Impact of Single-Walled Carbon Nanotube Functionalization on Ion and Water Molecule Transport at the Nanoscale
Auteur(s): Mejri Alia, Arroyo Nicolas, Herlem Guillaume, Palmeri J., Manghi Manoel, Henn F., Picaud Fabien
(Article) Publié:
Nanomaterials, vol. 14 p.117 (2024)
Ref HAL: hal-04411217_v1
DOI: 10.3390/nano14010117
Exporter : BibTex | endNote
Résumé: Nanofluidics has a very promising future owing to its numerous applications in many domains. It remains, however, very difficult to understand the basic physico-chemical principles that control the behavior of solvents confined in nanometric channels. Here, water and ion transport in carbon nanotubes is investigated using classical force field molecular dynamics simulations. By combining one single walled carbon nanotube (uniformly charged or not) with two perforated graphene sheets, we mimic single nanopore devices similar to experimental ones. The graphitic edges delimit two reservoirs of water and ions in the simulation cell from which a voltage is imposed through the application of an external electric field. By analyzing the evolution of the electrolyte conductivity, the role of the carbon nanotube geometric parameters (radius and chirality) and of the functionalization of the carbon nanotube entrances with OH or COO− groups is investigated for different concentrations of group functions.
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