Pullulan-Based Polymer Surfactants for Vinyl Acetate Miniemulsion Polymerization: Kinetics and Colloidal Stability Investigations

International audienceVarious pullulan-b-Jeffamine block copolymers (Jeffamine is a PEO-b-PPO copolymer (PEO = poly(ethylene oxide), PPO = poly(propylene oxide)) are used as surfactants for vinyl acetate miniemulsion polymerization. Their influence on the kinetics, average molecular weights and colloidal stability, is compared with that of Pluronic F68, when using either organosoluble or hydrosoluble initiators. In the first case, conversions and molecular weights are not affected by the polymer surfactant, in contrast to what is observed when using the hydrosoluble system, that may be due to a reaction between the incoming radicals and the sugar units of the pullulan chain. Long-term colloidal stability between 4 degrees C and 40 degrees C over more than 4 months is observed and is not affected by the addition of salts when using pullulan-based surfactant

Association states of multisensitive smart polysaccharide–block-polyetheramine copolymers

International audienceAbstract : The water soluble properties of different copolymers based on pullulan-block-polyetheramine have been deeply studied. The polyetheramine group (PEA) corresponding to a propylene oxyde/ethylene oxyde ratio (PO/EO) of 29/6, is condensed, via amine link, to pullulans with various chain lengths. Different polysaccharide/PEA (PS/PEA) ratio copolymers have been investigated through macroscopic (cloud point, enthalpy) and mesoscopic scale approaches (critical aggregation concentration (CAC), mean number average hydrodynamic diameter (Dh) or aggregation number (Nag)). These systems are both pH and/or thermo-sensitive. Finally, it seems that three states can describe such systems (i) isolated copolymers (unimers) below the CAC, (ii) water soluble aggregates above the CAC and whatever the PS/PEA ratio is due to hydrophobic interactions and (iii) non-soluble aggregates (above the critical temperature) due to dehydration of polyetheramine groups but only if PS/PEA ratio is low enough

Toward tunable amphiphilic copolymers via CuAAC click chemistry of oligocaprolactones onto starch backbone

International audienceStarch-based tunable amphiphilic copolymers are easily obtained by grafting polycaprolactone chains via 1,3 dipolar Copper-Catalyzed Azide-Alkyne Cycloaddition (click chemistry CuAAC), starting from propargylated starch and azido oligocaprolactones with different chain lengths as the precursors. The copolymers are characterized by (1)H and (13)C NMR, from which a degree of substitution of starch can tentatively be deduced. Besides these bulk characterizations, the surface of the functionalized starch is also characterized by XPS which confirms the triazole formation, particularly through the deconvolution of the N 1s peak, and by ToF-SIMS which, not only confirms the surface modification, but also highlights the disappearance of the Cu(+) cations. The solubility and swelling behaviours of these copolymers have been investigated, which clearly show the dependence both on the solvent and the PCL chain length. These investigations highlight the swelling dependence on the δd component of the Hansen solubility parameter of solvents. Finally, at low concentration, they present the capacity to organize themselves in aggregates in aqueous solutions, as seen from TEM and DLS investigations

Evolution of the water-monomer dynamic interfacial properties during methyl methacrylate radical polymerization in a single monomer droplet: dependence on the chemical structure of the surfactant

International audienceThis paper deals with the monitoring of the methyl methacrylate (MMA) droplet interface during its polymerization in one single monomer droplet by using a drop tensiometer. The droplet is stabilized by various molecular and polymer surfactants, in particular Pluronic® F68 and pullulan-block-Jeffamine®. The polymerization in one single droplet of the tensiometer can be seen as a way to study the interface of polymer nanoparticles during a mini-emulsion polymerization assuming the concept of a perfect nanoreactor. It was found that the experimental results (surface tension and interfacial rheology) can be connected with MMA radical polymerization. These results demonstrate that the drop tensiometer technique enables interface evolution to be followed during polymer polymerization

Recherche de zones fracturees de faible extension par la mise en oeuvre d'un profil sismique vertical et l'application de l'analyse spectrale a entropie maximale

Available from CEN Saclay, Service de Documentation, 91191 Gif-sur-Yvette Cedex (France) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Chirurgische handasepsie in de diergeneeskunde: evaluatie van een zeep scrub en een alcoholische rub techniek

peer reviewedRecent evidence shows hydro-alcoholic solutions are more efficient than traditional medicinated soaps in the presurgical hand antisepsis of human surgeons. However, little veterinary literature is available on the subject. The aims of this study were to compare the efficiency of medicinated soaps and a hydro-alcoholic solution prior to surgery using an in use testing method in a veterinary setting. A preliminary trial was performed that compared the mean Log10 number of bacterial colony forming units (CFU) and the reduction factors (RF) between 2 five-minute hand-scrubbing sessions using different soaps (povidone iodine (PVP) and chlorhexidine gluconate (CHX)) and the 1.5-min application of a hydro-alcoholic rub (Sterillium). A clinical in use trial comparing mean log10 number of bacterial CFU’s and RF for Sterillium and CHX soap was performed in a surgical set-up. Sampling was performed using finger printing on agar plates. Sterillium and CHX had a similar immediate effect, although the sustained effect was significantly better for Sterillium. PVP showed a significantly lower immediate and sustained effect. Sterillium showed good efficiency in the clinical trial. This study shows that, as previously reported for human medicine, Sterillium can safely be considered as an attractive alternative method for surgical hand antisepsis in a veterinary surgical setting

Surgical hand antisepsis in veterinary practice: Evaluation of soap scrubs and alcohol based rub techniques

peer reviewedRecent evidence shows hydro-alcoholic solutions are more efficient than traditional medicinated soaps in the presurgical hand antisepsis of human surgeons. However, little veterinary literature is available on the subject. The aims of this study were to compare the efficiency of medicinated soaps and a hydro-alcoholic solution prior to surgery using an in use testing method in a veterinary setting. A preliminary trial was performed that compared the mean Log10 number of bacterial colony forming units (CFU) and the reduction factors (RF) between 2 five-minute hand-scrubbing sessions using different soaps (povidone iodine (PVP) and chlorhexidine gluconate (CHX)) and the 1.5-min application of a hydro-alcoholic rub (Sterillium). A clinical in use trial comparing mean log10 number of bacterial CFU’s and RF for Sterillium and CHX soap was performed in a surgical set-up. Sampling was performed using finger printing on agar plates. Sterillium and CHX had a similar immediate effect, although the sustained effect was significantly better for Sterillium. PVP showed a significantly lower immediate and sustained effect. Sterillium showed good efficiency in the clinical trial. This study shows that, as previously reported for human medicine, Sterillium can safely be considered as an attractive alternative method for surgical hand antisepsis in a veterinary surgical setting