Glaive, AS ; Coeur, C ; Guigner, JM ; Amiel, C ; Volet, G

The amphiphilic heterograft copolymers bearing biocompatible/biodegradable grafts [poly-(2-methyl-2-oxazoline-co-2-pentyl-2-oxazoline)-g-poly-(D-L-lactic acid)/poly-(2-ethyl-2-oxazoline)] were synthesized successfully by the combination of cationic ring-opening polymerization and click chemistry via the <"grafting to"> approach. The challenge of this synthesis was to graft together hydrophobic and hydrophilic chains on a hydrophilic platform based on PMeOx. The efficiency of grafting depends on the chemical nature of the grafts and of the length of the macromolecular chains. The self-assembly of these polymers in aqueous media was investigated by DLS, cryo-TEM, and SANS. The results demonstrated that different morphologies were obtained from nanospheres and vesicles to filaments depending on the hydrophilic weight ratio in the heterograft copolymer varying from 0.38 until 0.84. As poly-(2-ethyl-2-oxazoline) is known to be thermoresponsive, the influence of temperature rise on the nanoassembly stability was studied in water and in a physiological medium. SANS and DLS measurements during a temperature ramp allowed to show that nanoassemblies start to self-assemble in "raspberry like" primary structures at 50 degrees C, and these structures grow and get denser as the temperature is increased further. These amphiphilic heterograft copolymers may include hydrophobic drugs and should find important applications for biomedical applications which require stealth properties.

https://doi.org/10.1021/acs.langmuir.3c02772

News regularly point out all the beauty but also the potential dangers of volcanic eruptions. If one can appreciate the show of these natural phenomena, one also seeks to understand them better in order to protect the neighbouring populations and to evaluate their impact on the climate evolution.

Eruptions at Stromboli (Italy) occur as periodic explosions (~15 mn) projecting fragments of molten lava to a few hundred meters above the crater. This type of explosions, so-called "Strombolian", is observed on many volcanoes worldwide, among which  Mount Etna as again verified recently. The driving mechanism of the explosions is well known: large gas pockets (slugs) that are formed by coalescence of small bubbles at depth in the magma rise rapidly across the volcanic conduits and bursts explosively while reaching the surface. However, the depth of origin of these gas slugs remained uncertain; it  was indirectly estimated from the analysis of seismic and acoustic signals associated with the explosions. In a new study published in "Science" (July 2007, [1]), researchers from the Pierre Sue Laboratory (CNRS-CEA, Saclay) and the National Institute of Geophysics and Volcanology of Italy (INGV, Catania) determine for the first time the depth of origin of strombolian explosions.