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New antimicrobial polymer composite based on commercial polyurethane (PU) Laripur®LPR9020 and polymeric biocide polyhexamethylene guanidine hydrochloride (PHMG-Cl) has been prepared by solvent casting method. Modified PU films containing from 1 to 4 wt% of PHMG-Cl were characterized in terms of mechanical, thermal and surface properties, biocide release behavior, as well as antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) bacterial strains. The results of mechanical testing indicate that the introduction of PHMG-Cl did not cause noticeable changes in the tensile strength of PU films, but improved their elasticity by at least 20–30%. The surface of PU/PHMG-Cl films was found to possess significantly higher hydrophobicity than neat polymer that is manifested in sharply increased water contact angle value from 72° for neat PU to 95° for PU/PHMG-Cl (2%). According to thermogravimetric analysis data, PU/PHMG-Cl composites are thermally stable to at least 300 °C which indicate their availability for melt processing by common methods. The results of differential scanning calorimetry showed reduction of both glass transition and melting temperatures of PU by more than 7 °C when contained only 1% of PHMG-Cl. Gradual release of polymeric biocide from modified PU films into water has been detected spectrophotometrically. The total biocide release ratio was found to be in the range from 29% to 48% after 50 hours immersion, depending on its content in polymer composite. PU/PHMG-Cl films showed much lower leaching rate into physiological saline solution compared to pure water (from 10% to 21% after 50 hours), which may be caused by poor solubility of polymeric biocide in sodium chloride solutions. The study of antibacterial activity of modified PU films using both disc agar diffusion and contact methods indicate high efficacy against tested microorganisms when contained 3% of polymeric biocide. So, this approach, based on the modification of PU resin with polymeric biocide PHMG-Cl, has been discussed in terms of potential medical applications when biocide release system or contact active material are necessary.

Fouling release coatings are known to be ecofriendly and to be a good alternative to the coatings containing biocides. To improve their efficiency and lifespan the incorporation of additives seems required. Amphiphilic system as PEG-silicone coatings have a lower impact on the environment. However, PEG oxidation in seawater impacts its lifespan. In this context, the development and incorporation of new hydrophilic additives offers great potentiel. The objective of this study is to design an amphiphilic fouling release coating containing poly(oxazoline) (POx) as additives. POx have similar physical properties as PEG and have already been used in biomedical applications. POx with a trimethoxysilane end-group has been synthesized to be crosslinked in a RTV silicone coating. The impact of its incorporation in a PDMS coating has been evaluated on surface properties and on coating organization. The results have been compared with a similar PEG-silicone coating. In addition, microbiologic assays have been carried out to evaluate the bacterial adhesion and the fouling properties of the coating. Two biomedicals bacteria and a marine bacterium were used to confirm the interest of POx. POx-silicone coating showed similar fouling efficiency against bacteria as PEG-silicone coating despite a bigger surface roughness and a lower compatibility with PDMS.

Different polytypes of SiC are described and predicted in literature. Here, we report the first occurrence of an orthorhombic 6O-SiC polytype as rock-forming mineral in the nickel laterite mine of Tiebaghi (New Caledonia). This new class of SiC crystallizes in the space group Cmc21 with 12 atoms per unit cell [a = 3.0778(6) Å, b = 5.335(2) Å, c = 15.1219(6) Å, α = 90°, β = 90°, γ = 120°]. The density of 6O-SiC is about 3.22 g/cm3 and the calculated indirect bandgap at room temperature of 3.56 eV is identical to 6H-SiC. Our results suggest that 6O-SiC is the intermediate state in the wurtzite to rocksalt transformation of 6H-SiC.

International audience; Filamentous fungi are present everywhere in our environment and can grow on almost any substance in presence of moisture. Protecting the indoor environment against microbial growth remains a complex issue especially in sanitary applications or where protection against moulds is critical. Silicone samples containing 2% or 5% (w/w) of the cationic biocides polyhexamethylene guanidine dodecylbenzenesulfonate (PHMG-DBS), 1-octyl-3-me-thylimidazolium tetrafluoroborate (OMIM-BF 4) or 1-dodecyl-3-methylimidazolium tetrafluoroborate (DMIM-BF 4) were tested against a series of fungal species implicated in indoor fungal contamination. Our investigations were conducted according to the international standard ISO 16869 i.e. with a carbon-poor Nutrient-Salt-Agar (NSA) culture medium, and also with a carbon-rich Peptone-Dextrose-Agar (PDA) culture medium composed of pancreatic peptone, glucose and agar-agar as the spore suspension agar overlay. The experimental protocol using the PDA medium proved to be the most efficient procedure for discriminating, in a week only, the control analysis and those using modified silicones. Our results demonstrate that silicones containing 5% of polymeric biocide PHMG-DBS present higher antifungal activity on the filamentous fungi than longchain imidazolium ionic liquids-containing silicones. The possible mechanisms of antifungal action of cationic biocides are discussed. The efficacy of PHMG-DBS demonstrates that such modified-silicones can prevent microbial growth and silicone deterioration by microorganisms in areas with high humidity levels such as kitchens and bathrooms as well as hospitals and microbiology laboratories.

New protic ionic liquid N-butylguanidinium tetrafluoroborate (BG-BF4) has been synthesized by single-step method. The ionic liquid is thermally stable to at least 300 °C and has ionic conductivity value of 8⋅10−3 S/cm at room temperature increasing to 0.18 S/cm at 180 °C. To develop a new proton conducting membrane, the nano-fibrillar matrix of bacterial cellulose (BC) has been impregnated with BG-BF4. The composite BC/BG-BF4 membrane containing 80 wt% of ionic liquid was found to have tensile strength of 35 MPa and ionic conductivity of 4.5⋅10−4 S/cm at 180 °C. The high saturation of BC with protic ionic liquid to 95 wt% allowed obtain composite membrane with reduced tensile strength of 6 MPa but excellent ionic conductivity of 5.2⋅10−2 S/cm at 180 °C. The deposition of polyaniline (PANI, emeraldine base) into BC matrix by oxidative polymerization of aniline on the surface of cellulose nanofibrils was found to improve the ionic conductivity of BC/BG-BF4 system significantly, reaching the value of 4⋅10−3 S/cm at 180 °C for cellulose film containing 80 wt% of ionic liquid. According to results of dynamical mechanical analysis (DMA), both BC/BG-BF4 and BC/PANI/BG-BF4 composites keep excellent storage modulus values at 180 °C (1000 MPa and 835 MPa, respectively). Due to the excellent holding capacity of BC matrix to ionic liquid, as well as good thermal and mechanical properties of BC/BG-BF4 composite it can be promising material for the fabrication of proton conducting membranes for fuel cells operating at elevated temperatures in water free conditions.

Plastic pollution has become one of the most visible environmental issue. Studying the aging and the fragmentation mechanism of polymers therefore raises environmental and health issues. Since it is particularly difficult to monitor all these processes in the real environment, laboratory studies are still necessary to obtain more accurate data and to identify the pathways leading to the outcome of plastic debris in the environment. In this paper we present a new method to prepare micrometer thick LDPE films with different thicknesses and controlled crystalline morphologies (i.e. spherulite size) using dip-coating process. LDPE films presenting different spherulite dimensions were submitted to an accelerated weathering test which indicates that spherulite size has only a weak influence on the rate of photo-oxidation. However, films presenting large spherulites morphologies seem to be more sensitive to surface erosion and crack initiation. We believe that the method developed in this paper can be used to study with more control and more rapidly (i.e. thin film and accelerated weathering) the influence of crystalline morphology on a wide range of semi-crystalline polymers in different ageing conditions and thus help to better understand the fragment production of plastics in the environment.

International audience; La2-xNdxCuO3.5 (x ≤ 0.5) compounds have been synthesized by a topotactic reduction reaction with calcium hydride at 280 °C for 48 h. Structural, thermal, vibrational and magnetic properties of La2-xNdxCuO3.5 (x ≤ 0.5) were studied by X-ray powder diffraction (XRD), by differential thermal analysis (DTA) and temperature dependent powder X ray diffraction (TDXD), by Raman spectroscopy and by electronic paramagnetic resonance. The oxidation of the compounds La2-xNdxCuO3.5 (x ≤ 0.5) at 400 °C for 24 h kinetically stabilizes the compounds La2-xNdxCuO4 (x ≤ 0.5) with an I4/mmm type structure. The phase relationship between T’ and T, ensured at high temperature, was followed and discussed by thermal and structural analysis.

A new polymeric biocide polyhexamethylene guanidine (PHMG) molybdate has been synthesized. The obtained cationic polymer has limited water solubility of 0.015 g/100 mL and is insoluble in paint solvents. The results of acute toxicity studies indicate moderate toxicity of PHMG molybdate, which has a median lethal dose at 48 h of 0.7 mg/L for Daphnia magna and at 96 h of 17 mg/L for Danio rerio (zebrafish) freshwater model organisms. Commercial ship paint was then modified by the addition of a low concentration of polymeric biocide 5% (w/w). The painted steel panels were kept in Dnipro River water for the evaluation of the dynamics of fouling biomass. After 129-d exposure, Bryozoa dominated in biofouling of tested substrates, forming 86% (649 g/m2 ) of the total biomass on control panel surfaces. However, considerably lower Bryozoa fouling biomass (15 g/m2 ) was detected for coatings containing PHMG molybdate. Dreissenidae mollusks were found to form 88% (2182 g/m2 ) of the fouling biomass on the control substrates after 228 d of exposure, whereas coatings containing PHMG molybdate showed a much lower biomass value of 23.6 g/m2 . The leaching rate of PHMG molybdate in water was found to be similar to rates for conventional booster biocides ranging from 5.7 μg/cm2 /d at the initial stage to 2.2 μg/cm2 /d at steady state. Environ Toxicol Chem 2017;36:2543-2551. © 2017 SETAC.

International audience; This paper reports on the synthesis and physical properties of conducting composites based on polyaniline and polystyrene. Polyaniline composite powders are synthesized by oxidative polymerization in an acidic medium. Thermal properties are characterized by thermo gravimetric analysis and differential scanning calorimetry. UV-Visible absorption spectroscopy is also used to study the optical properties of the deposited films. The optical gap decreases from 4.6 eV to 2.7 eV with increasing polyaniline content from 0.5 to 5 wt. % confirming the improvement of the semi-conductive properties. Due to the absorption properties in near infrared of the thin composite layers they can be promising materials for optoelectronic and photovoltaic applications.

New hydrophobic protic ionic liquid, 2-butylaminoimidazolinium bis(trifluoromethylsulfonyl)imide (BAIM-TFSI), has been synthesized. The ionic liquid showed good thermal stability to at least 350 °C. The conductivity of BAIM-TFSI determined by electrochemical impedance method was found to be 5.6 × 10−2 S/cm at 140 °C. Homogeneous composite films based on commercial polyimide (PI) Matrimid and BAIM-TFSI containing 30–60 wt% of ionic liquid were prepared by casting from methylene chloride solutions. Thermogravimetric analysis data indicated an excellent thermal stability of PI/BAIM-TFSI composites and thermal degradation points in the temperature range 377 °C–397 °C. The addition of ionic liquid up to 50 wt% in PI films does not lead to any significant deterioration of the tensile strength of the polymer. The dynamic mechanical analysis results indicated both an increase of storage modulus E′ of PI/BAIM-TFSI composites at room temperature and a significant E′ decrease with temperature compared with the neat polymer. The cross-linking of the PI with polyetheramine Jeffamine D-400 allowed to prepare PI/Jeffamine/BAIM-TFSI (50%) membrane with E′ value of 300 MPa at 130 °C. The ionic conductivity of this cross-linked composite membrane reached the level of 10−2 S/cm at 130 °C, suggesting, therefore, its potential use in medium-temperature fuel cells operating in water-free conditions.

International audience; A new telechelic liquid natural rubber is used to elaborate thin coating (

International audience; Borosilicate glasses are considered for the long-term confinement of high-level nuclear wastes. External irradiations with 1 MeV He+ ions and 7 MeV Au5+ ions were performed to simulate effects produced by alpha particles and by recoil nuclei in the simulated SON68 nuclear waste glass. To better understand the structural modifications, irradiations were also carried out on a 6-oxides borosilicate glass, a simplified version of the SON68 glass (ISG glass). The mechanical and macroscopic properties of the glasses were studied as function of the deposited electronic and nuclear energies. Alpha particles and gold ions induced a volume change up to −0.7% and −2.7%, respectively, depending on the glass composition. Nano-indentations tests were used to determine the mechanical properties of the irradiated glasses. A decrease of about −22% to −38% of the hardness and a decrease of the reduced Young's modulus by −8% were measured after irradiations. The evolution of the glass structure was studied by Raman spectroscopy, and also 11B and 27Al Nuclear Magnetic Resonance (MAS-NMR) on a 20 MeV Kr irradiated ISG glass powder. A decrease of the silica network connectivity after irradiation with alpha particles and gold ions is deduced from the structural changes observations. NMR spectra revealed a partial conversion of BO4 to BO3 units but also a formation of AlO5 and AlO6 species after irradiation with Kr ions. The relationships between the mechanical and structural changes are also discussed

The choice of efficient antimicrobial additives for polyamide resins is very difficult because of their high processing temperatures of up to 300 &deg, C. In this study, a new, thermally stable polymeric biocide, polyhexamethylene guanidine 2-naphtalenesulfonate (PHMG-NS), was synthesised. According to thermogravimetric analysis, PHMG-NS has a thermal degradation point of 357 &deg, C, confirming its potential use in joint melt processing with polyamide resins. Polyamide 11 (PA-11) films containing 5, 7 and 10 wt% of PHMG-NS were prepared by compression molding and subsequently characterised by FTIR spectroscopy. The surface properties were evaluated both by contact angle, and contactless induction. The incorporation of 10 wt% of PHMG-NS into PA-11 films was found to increase the positive surface charge density by almost two orders of magnitude. PA-11/PHMG-NS composites were found to have a thermal decomposition point at about 400 &deg, C. Mechanical testing showed no change of the tensile strength of polyamide films containing PHMG-NS up to 7 wt%. Antibiofilm activity against the opportunistic bacteria Staphylococcus aureus and Escherichia coli was demonstrated for films containing 7 or 10 wt% of PHMG-NS, through a local biocide effect possibly based on an influence on the bacterial eDNA. The biocide hardly leached from the PA-11 matrix into water, at a rate of less than 1% from its total content for 21 days.

Controlling adsorption of proteins onto medical devices is a key issue for implant-related infections. As self-assembled monolayers (SAMs) on titanium oxide represent a good model to study the surface-protein interactions, TiO 2 surface properties were modified by grafting bisphosphonate molecules terminated with hydrophilic poly(ethylene glycol) groups and hydrophobic perfluoropolyether ones, respectively. Characterisation of the surface chemistry and surface topography of the modified surfaces was performed using XPS and atomic force microscopy (AFM). Quartz-crystal microbalance with dissipation (QCM-D) was used to determine the mass of adsorbed proteins as well as its kinetics. Poly(ethylene glycol)-terminated SAMs were the most effective surfaces to limit the adsorption of both BSA and fibrinogen in comparison to perfluorinated-terminated SAMs and non-modified TiO 2 surfaces, as expected. The adsorption was not reversible in the case of BSA, while a partial reversibility was observed with Fg, most probably due to multilayers of proteins. The grafted surfaces adsorbed about the same quantity of proteins in terms of molecules per surface area, most probably in monolayer or island-like groups of adsorbed proteins. The adsorption on pristine TiO 2 reveals a more important, non-specific adsorption of proteins.

The effects of laser irradiation on γ-Fe2O3 4 ± 1 nm diameter maghemite nanocrystals synthesized by co-precipitation and dispersed into an amorphous silica matrix by sol-gel methods have been investigated as function of iron oxide mass fraction. The structural properties of γ-Fe2O3 phase were carefully examined by X-ray diffraction and transmission electron microscopy. It has been shown that γ-Fe2O3 nanocrystals are isolated from each other and uniformly dispersed in silica matrix. The phase stability of maghemite nanocrystals was examined in situ under laser irradiation by Raman spectroscopy and compared with that resulting from heat treatment by X-ray diffraction. It was concluded that ε-Fe2O3 is an intermediate phase between γ-Fe2O3 and α-Fe2O3 and a series of distinct Raman vibrational bands were identified with the ε-Fe2O3 phase. The structural transformation of γ-Fe2O3 into α-Fe2O3 occurs either directly or via ε-Fe2O3, depending on the rate of nanocrystal agglomeration, the concentration of iron oxide in the nanocomposite and the properties of silica matrix. A phase diagram is established as a function of laser power density and concentration.

Water immiscible ionic liquid 1-dodecyl-3-methylimidazolium tetrafluoroborate (DMIM-BF 4 ) and its inclusion complex with β-cyclodextrin (β-CD) in molar ratio 1:1 have been synthesized. The formation of DMIM-BF 4 /β-CD complex was confirmed by FT-IR analysis, 1 H NMR analysis, and differential scanning calorimetry data. Our results indicate that the aliphatic tail of DMIM-BF 4 is included into β-CD inner cavity whereas imidazolium ring is located outside the torus. Moreover, the weak interaction between polar components of ionic liquid and hydrophilic outer surface of β-CD has also been detected. The standard agar disk diffusion method was performed to evaluate antimicrobial efficiency of the obtained compounds against Staphylococcus aureus (ATCC-25923), Escherichia coli (ATCC-25922) and Pseudomonas aeruginosa (ATCC-27853), Candida albicans (M 885 ATCC 10231) and its clinical isolate test-cultures. It has been found that both DMIM-BF 4 and DMIM-BF 4 /β-CD complex possess high antimicrobial activity as revealed by similar zone inhibition values against all tested microorganisms. The acute toxicity studies on Danio rerio (zebrafish) model organism showed that the pure ionic liquid DMIM-BF 4 is slightly toxic compound having LD 50 value of 7 mg/L, whereas DMIM-BF 4 /β-CD complex has considerably reduced toxicity (LD 50 = 100 mg/L) and therefore have potentially wider application areas.

International audience; In this work, we report on magnetic nanoparticles of CoxFe3-XO4 (x 0) gives spinel structure of space group Fd-3m for all samples. Magnetization curves, recorded by a Vibrating Sample Magnetometer (VSM), are the sign of two exchange-coupled magnetic phases (x > 0). This was in disagreement with XRD and SAED analyses which showed only one structural phase. Large (similar to 250 nm and less) rectangular and small spheroidal nanoparticles have been found by Transmission Electron Microscopy (TEM). The increase of cobalt content favors the formation of monodisperse nanoparticles. Following a subsequent heat treatment, a fraction of the as prepared samples (depending on x) has been transformed into hematite phase with a disappearance of the exchange-coupling behavior. In situ Micro-Raman analyses were necessary to investigate on the growing of the nanoparticles and the ferrite-hematite transformation. We have also deduced, that the synthesized phase with the cobalt ferrite one (till x < 1) was the magnetite Fe3O4. Then, we have pointed out the effect of performing local spectroscopy and the effect of having mixed ferrites on the structural and the physical properties. (C) 2016 Elsevier B.V. All rights reserved.

International audience; We investigated the carbon steel corrosion in carbon dioxide clay-rich environment to understand its behavior under geological conditions. The results show the formation of magnetite as the main corrosion product in the first step of the corrosion process, followed by the formation of different corrosion products with complex mixtures of iron-oxide, hydroxycarbonate, hydroxychloride and sulfide phases. These results strongly contrast with similar experiments conducted under H-2 atmosphere where the major corrosion products consisted of iron sulfides. It appears then important to consider all the geochemical parameters including gas composition to better study corrosion of steel buried in geological formations. (C) 2014 Elsevier Ltd. All rights reserved.

To elaborate a new antimicrobial bacterial cellulose (BC) based material, the porous structure of BC has been combined with polymeric biocide polyhexamethylene guanidine hydrochloride (PHMG-Cl). A sufficient saturation of the BC matrix with PHMG-Cl and the formation of hydrogen bonds between chloride ions of the polymeric biocide and the hydroxyl groups of BC was confirmed by FT-IR analysis. The formation of an interconnected network of fiber bundles within the cellulose-based composite after the introduction of PHMG-Cl was revealed by Atomic Force Microscopy (AFM). The modified PHMG-Cl biocide bacterial cellulose film specimens showed excellent efficacy against multidrug resistant strains Staphylococcus aureus and Klebsiella pneumonia IMBG233, the phytopatogenic Xanthomonas campestris pv. campestris IMBG299 and Pseudomonas syringae pv. tomato DC3000, as well as yeast. Moreover, the introduction of PHMG-Cl also prevented a biofilm formation by a model association of pro- and eukaryotic microorganisms and stopped de novo cellulose synthesis in the existed biofilm. The biocide release rate from BC matrix was shown to depend on the moisture content of the composite films. PHMG-Cl-embedded cellulose is therefore a new formulation of biocide which could be further used for wounds healing.

© 2014 by Pleiades Publishing, Ltd. In this work we assessed the performance of the density functional theory (DFT) approach through a comparison study with the experimental Raman spectrum obtained for [4-[( E)-phenylazo]phenyl]ethanol (ABOH) in the wave number range 900-1800 cm-1. The assignment of the ten most active vibrational modes is achieved using the hybrid B3LYP method with the 6-311++G(2d,2p) basis set. Two molecules of reference [N-ethyl-4-[( E)-(4-nitrophenyl)azo]anilino]ethanol (Disperse Red 1, DR1) and 4-[( E)-(4-nitrophenyl) azo]aniline (Disperse Orange 3, DO3) are also investigated in order to consider this method in the calculation of the Raman intensities. The experimental Raman spectrum of DR1 is compared with those of the three stable configurations obtained at the B3LYP/6-311++G(2 d,2p) level.

In diatoms, the main photosynthetic pigments are chlorophylls a and c, fucoxanthin, diadinoxanthin and diatoxanthin. The marine pennate diatom Haslea ostrearia has long been known for producing, in addition to these generic pigments, a water-soluble blue pigment, marennine. This pigment, responsible for the greening of oysters in western France, presents different biological activities: allelopathic, antioxidant, antibacterial, antiviral, and growth-inhibiting. A method to extract and purify marennine has been developed, but its chemical structure could hitherto not be resolved. For decades, H. ostrearia was the only organism known to produce marennine, and can be found worldwide. Our knowledge about H. ostrearia-like diatom biodiversity has recently been extended with the discovery of several new species of blue diatoms, the recently described H. karadagensis, H. silbo sp. inedit. and H. provincialis sp. inedit. These blue diatoms produce different marennine-like pigments, which belong to the same chemical family and present similar biological activities. Aside from being a potential source of natural blue pigments, H. ostrearia-like diatoms thus present a commercial potential for aquaculture, cosmetics, food and health industries.

In this paper, we studied the effect of sulfide ions on the corrosion behavior of carbon steel to simulate the geological disposal of high-level radioactive waste. In geological storage conditions, sulfidogenic environment was sustained by sulfate-reducing bacteria. Corrosion tests were conducted in systems in a controlled atmosphere of 5% H-2/N-2. Batch experiments were conducted at 30A degrees C for 1 month with steel coupons immersed in Na2S solutions. The structural characterization of the corrosion products was investigated by scanning electron microscope/energy dispersive x-ray spectroscopy, confocal micro-Raman spectrometry, and x-ray diffraction. In the absence of sulfide ion, a magnetite (Fe3O4) corrosion product layer was formed on steel surface while in the presence of sulfide ions we observed the formation of a poorly crystallized irons sulfide at low-sulfide concentration (1 mg/L) and a solid adherent pyrrhotite layer at higher sulfide concentration (5-15 mg/L). The strong drop in steel corrosion rate with sulfide concentration was revealed and related to the formation of well-crystallized pyrrhotite.

International audience; The mackinawite mineral was prepared as a carbon steel corrosion product in sulfidogenic waters at 90 degrees C after 2 months. The tetragonal crystal structure of the material was confirmed by Rietveld refinement of X-ray diffraction (XRD) data, and vibrational modes were analysed by micro-Raman spectroscopy. Despite a large number of studies on the formation and the stability of tetragonal mackinawite, the interpretation of the Raman spectra remains uncertain. In the present study, we report on the first calculation of the Raman-active vibrational modes of mackinawite using Density Functional Perturbation Theory and direct methods with BLYP + dispersion correction. Based on the comparison between calculated and experimental results, the four fundamental vibrational modes were assigned as 228 cm(-1) (B-1g), 246 cm(-1) (E-g), 373 cm(-1) (A(1g)) and 402 cm(-1) (E-g).

We have tested silicones containing 2% or 5% of the cationic biocides polyhexamethylene guanidine dodecylbenzenesulfonate (PHMG-DBS), 1-octyl-3-methylimidazolium tetrafluoroborate (OMIM-BF4) or 1-dodecyl-3-methylimidazolium tetrafluoroborate (DMIM-BF4) against the major relevant bacterial and yeast species in health care-associated infections (HCAI). Study conducted according to the international standard ISO 22196 revealed that silicones containing 2% or 5% DMIM-BF4 or 5% PHMG-DBS presented the highest antimicrobial activity, leading to a logarithmic growth reduction of 3.03 to 6.46 and 3.65 to 4.85 depending on the bacterial or fungal species. Heat-pretreated silicones containing 2% DMIM-BF4 kept a high activity, with at least a 3-log reduction in bacterial growth, except against P. aeruginosa where there was only a 1.1-log reduction. After 33days, the release ratio of cationic biocide from silicone films containing 5% of DMIM-BF4 was found to be 5.6% in pure water and 1.9% in physiological saline solution, respectively. No leaching of PHMG-DBS polymeric biocide was detected under the same conditions. These results demonstrate unambiguously that silicones containing 2% DMIM-BF4 or 5% PHMG-DBS present high antimicrobial activity, as well as high leaching resistance and therefore may be good candidates for the development of safer medical devices.

Calcium carbonate (CaCO3)/iron oxide composites were synthesized through a simple one-step impregnation procedure by mixing iron oxide nanoparticles (γ-Fe2O3 and Fe3O4) of about 6 nm in size and CaCO3 microparticles (Φ = 2 µm–8 µm, vaterite phase). The morphology and structural properties of CaCO3, iron oxide nanoparticles and CaCO3/iron oxide composites were characterized as a function of low iron content (0 %w to 3.2 %w) by scanning electron microscopy and transmission electron microscopy, X-ray diffraction and 57Fe Mossbauer spectrometry. The phase transformations induced by thermal treatment and laser irradiation were investigated in situ by X-ray thermodiffraction (XRTD) and Raman spectroscopy. We have shown that the phase transformations observed by XRTD are also observed under laser irradiation as a consequence of the absorption of the laser irradiation by iron oxide nanoparticles. Copyright © 2012 John Wiley & Sons, Ltd.

Water-resistant polymeric biocide poly(hexamethylene guanidine) dodecylbenzenesulfonate (PHMG-DBS) was synthesized by anion metathesis between poly(hexamethylene guanidine) hydrochloride and sodium dodecylbenzenesulfonate and subsequently characterized using elemental analysis, Raman spectroscopy and thermogravimetric analysis. It is found that PHMG-DBS is thermally stable to at least 350 °C, which makes it suitable for melt blending with polyamide (PA) resins. An antifungal PA-12 composition was prepared by compression moulding of PA-12 and PHMG-DBS powder mixture at 240 °C. The characteristics of the prepared films were investigated: surface roughness and hydrophobicity using atomic force microscopy and contact angle measurements, respectively. No significant change in the material characteristics is observed compared to pure PA-12 films. PA-12 films containing 2 wt% of the PHMG-DBS biocide are found to be highly resistant against Trychophyton mentagrophytes fungus. Copyright © 2012 Society of Chemical Industry

Conducting polymer composite films based on different aliphatic polyamides (PA) (PA-6, PA-11 and PA-12) have been synthesized by in situ aniline polymerization inside a surface layer of the PA host matrix. Dielectric permittivity and dielectric loss of these films are explained in terms of the interfacial polarization. The real part of permittivity is found to be higher in the PA/polyaniline (PANI) composite films than in the virgin PA polymer matrix. Such behaviour is attributed to the interaction between PA and PANI molecular chains and to the conductivity increase after the aniline polymerization. The performed confocal Raman spectrometry and X-ray diffraction studies also confirmed the presence of interactions between PA and PANI molecular chains.

Ellipsometry was used as a technique to determine glass temperature transitions of homopolymer thin films of polystyrene and poly(methyl methacrylate) ranging from 5 to 200 nm. The technique operated systematically at various energies reveals the presence of multiple transitions in these films under certain conditions of preparation. It was observed that in the case of strong polymer–substrate interactions, several Tg were measured and ascribed to a layered structure in the film. In the absence of strong interactions, a more uniform film presenting a single Tg was observed no matter the thickness. The results confirm the recent assumption of thin films organised in multilayers and emphasize the importance of using a highly sensitive multi-wavelength technique in probing such properties.

Composite polyurethane/polyaniline and polyamide-6/polyaniline films were chemically prepared by oxidative in situ polymerization of aniline inside the previously swelled matrix film. Swelling kinetic studies had shown that for polyurethane and polyamide-6 films the swelling degree of aniline was 25 wt.% and 15 wt.%, respectively. The dielectric and electrical properties of the composite films were established using dielectric relaxation spectroscopy and four-probe method. Dielectric measurements as a function of temperature and frequency revealed the presence of relaxation processes influenced by the nature of the polymer matrix, i.e. one relaxation process for the polyurethane based composite film and two relaxation processes for polyamide-6 based composite film. These relaxations were explained in terms of interfacial polarization caused by the polyaniline organisation as it was revealed by atomic force microscopy. Activation energy values obtained by dielectric and electrical measurements are close and this result confirms the conducting character of the polyaniline containing layer.

Adding elastomeric particles (Sunigum®) into a polyethylene (PE) matrix leads to an increase of both viscosity and dynamic moduli in the molten state. This suspension effect is more pronounced if the particle's dispersion is improved with a compatibilizing agent. However, under capillary flow, the blends exhibit a more complex behavior with a strong violation of a viscosity mixing rule. To elucidate the origin of this observation, an analysis of extrudates by confocal micro Raman spectrometry has been carried out. A selective migration of the lowest viscosity component (at a given shear rate) toward the wall of the capillary die has been noted. This migration is inhibited by the addition of a compatibilizer. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers

The adhesion of the biocompatible hydrophilic polymer, poly (vinyl alcohol) to a model substrate, silicon, was investigated. Contact angle measurements were used to reveal the effect of various substrate cleaning procedures including sonication and UV–ozone treatment prior to casting a 35 μm coating. Raman microspectrometry and X-ray reflectometry were used to characterise the composition and the thickness of PVA thin films. The use of mechanical abrasion of the substrate followed by a 131 nm primer layer of PVA in combination with vacuum treatment at temperatures higher than the glass transition temperature ( T g = 80 °C) provided the best resistance to delamination as demonstrated by visual observation during prolonged immersion of the coatings in water.

The preparation of the title compounds involves the introduction of the required Me 3 SiC C and trichlorosilyl groups at the termini of the alkyl chain via derivatization of easily accessible and inexpensive materials/reagents. Trichloro[ω-(trimethylsilyl)alkynyl]silanes are useful for the linkage to a hydroxylated silicon surface for multilayer formation and for further chemical modification of the tail group of the monolayer.

Since the invention of dye-sensitized nanocrystalline solar cells, research on organic/inorganic photovoltaic devices (which transform light into electric current), in which titanium dioxide (titania, TiO2) is the inorganic part, has increased. In addition to its photovoltaic sensitivity, TiO2 is also used as a photocatalyst for remediation of contaminated water and air. [1–5] The improvement of the sensitivity of TiO2 for photocatalytic applications is of social importance. This can be achieved for example by making highly structured mesoporous TiO2 thin films. [6] At the nanometer scale, photocatalytic characteristics are greatly enhanced by the increased surface area of the particles and modification of their optical properties due to size quantization. At the meso-scale, the proper spatial arrangement of layered inorganic materials can assist electron/ energy transfer. [7] Because of its chemical stability and

International audience; The homogeneity of the oxygen content of TSMTG-YBa2Cu3O7 − δ/Y2BaCuO5 composites has been investigated by micro-Raman spectrometry. The Y123 compound has been found to be very sensitive to the laser power, but a laser power of 0.04 mW has been shown to not to be harmful for the samples, even after 2 h of irradiation. Raman spectra have shown that the oxygen content of YBa2Cu3O7 − δ/Y2BaCuO5 ceramics is not homogeneous at the micrometer scale. In addition, no monotonic decrease of the oxygen content is observed from the periphery to the core of the sample, confirming that the oxygen uptake is not strictly controlled by a diffusion process.

International audience; This paper deals with the structural and optical properties of buried waveguides manufactured from mesoporous silicon films (as-formed porous silicon layers, after oxidation, after filling with active DR1 dyes). It is shown that the oxidation process only induced a weak morphology transformation. The 2D profiles of cross-sections of the waveguides by micro-Raman mapping were done in order to check the oxidation rate and to probe the DR1 filling of the layers. This latter appeared homogeneous but surprisingly is greater in the weaker porosity layer. The light propagation through these different waveguides was observed and losses were measured and analyzed. The losses decreased after oxidation but they increased after filling.

Composite polyamide‐12/polyaniline (PA‐12/PANI) films were prepared by a treatment of PA‐12 films swelled in aniline with a water solution of ammonium persulfate (APS) and HCl. The existence of a very thin (2 µm) subsurface PANI containing layer in the composite film was shown by confocal micro‐Raman resonance spectrometry. A combination of the micro‐Raman and UV–Vis measurements allowed determining the PANI concentration in this conductive layer. This approach allowed studying the kinetics of the matrix polymerization process. It is shown that this solid phase process has the strong kinetic specificity as compared with known solution based systems. It is suggested that this is due to not only the physical‐chemical interactions of aniline and formed PANI with amide groups of the matrix but also to a physical state of aniline localized in voids of the free volume of the matrix and to formation of the additional oxidant HOCl in the oxidizing solution.

By performing Atomic Force Microscopy measurements of pull-off force as a function of the temperature, we were able to probe the dynamic of supported thin polystyrene (PS) films. Thermal transitions induce modifications in the surface energy, roughness and surface modulus that are clearly detected by AFM and related to PS chain relaxation mechanisms. We demonstrated the existence of three transition temperatures that can be associated to the relaxation of polymer chains located at different depth regions within the polymer film. Independently of the film thickness, we have confirmed the presence of a region of high mobility for the polymer chains at the free interface. The thickness of this region is estimated to be above 7nm. The detection of a transition only present for film thicker than the gyration radius Rg is linked to the dynamics of polymer chains in a bulk conformation (i.e. not in contact with the free interface). We claim here that our results demonstrate, in agreement with other techniques, the stratification of thin polymer film depth profile in terms of relaxation behavior.

Density functional theory (DFT) calculations have been used to investigate the structural properties, dipole moments, polarizabilities, Gibbs energies, hardness, electronegativity, HOMO/LUMO energies, and chemical potentials of trans and cis configurations of eight para-substituted azobenzene derivatives. All properties have been obtained using the B3LYP functional and 6-31++G(d,p) basis set. The planar structures have been obtained for all optimized trans configurations. The energy difference between trans and cis configurations for considered derivatives was found to be between 64.2-73.1 kJ/mole. It has been obtained that the p-aminodiazo-benzene (ADAB) has the difference in the dipole moments between trans and cis forms higher than for trans and cis azobenzene.

Using Resonance Raman microspectrometry we identify polyenes as shell pigments in 13 gastropod, 1 cephalopod and 4 bivalve taxa. The pigments are either isolated polyenes or polyenes bound to other molecules. Polyenes are present in coloured parts of the shell of all investigated taxa. Pigments differ between taxa and there is no trivial relationship between colour, pigment and taxon. The same colour in different taxa may be due to different pigments; different colours in the same taxon are due to different pigments; different colour saturation is due to different concentration of the same pigment. The pigment polyenes are unsubstituted chains of 8 – 13 conjugated double-bonds (16 – 26 carbon atoms) in the chain, with terminals incorporating – CH3 groups. This is the first demonstration of polyenes as shell pigment in the Mollusca. We also identify a carotenoid as the external, yellow pigment in Cypraea moneta.

The synthesis of model long-chain hydrocarbons (C 13 and C 19 ) carrying a vinyl group and a trichloro- or a triethoxysilyl group at each end is reported. These compounds are suitable for linkage to a hydroxylated silicon surface and at the other end with vinyl group for further functionalization and multilayer formation.

The dielectric properties of conducting polymer composite films based on polyaniline located in a thin layer in the vicinity of the surface of different insulating polymer matrices (polyamide and poly(ethylene terephthalate)) have been studied using dielectric relaxation spectroscopy in a wide temperature and frequency range. Several relaxation processes related to the film surface conductivity and influenced by the nature of the polymer matrix have been found in these composites. The nature of the polymer matrix is found to influence the rate of aniline polymerization, the distribution of polyaniline clusters and the depth of aniline penetration as shown, respectively, by Conducting Probe AFM and Raman spectroscopy. These features are correlated to the dielectric behavior of the composite films.

A self-assembled zirconia-based film, produced at the air–water interface using sodium dodecyl sulphate (SDS) as the template, has been characterised by energy-dispersive X-ray reflectometry, X-ray diffraction, and X-ray fluorescence analysis. Long-range order due to the lamellar liquid crystalline arrangement of the surfactant micelles was significant enough to produce Bragg diffraction. X-ray fluorescence from the specimens in the electron microscope indicates that the principal component of the film contains zirconium, oxygen and sulphate, -suggesting that the film contains zirconium polyoxo ions and surfactant. Raman spectroscopy indicates the presence of a zirconium hydroxide.

Raman scattering signals recorded by microscopy from organic self-assembled monolayers (thin nanometric films of calibrated thickness) on silica substrates were found to be much stronger than those obtained from identical films assembled on bulk silicon substrates. This effect, observed in the backscattering geometry, is shown to result from interferences between the direct and reflected beams (including both the excitation and scattered radiation) in front of a smooth reflecting surface. Strong dependence of the effect on the distance between the sampled monolayer and the bulk silicon substrate allows enhancement of the Raman signals of organic monolayer films on silicon by factors up to approximately 70 by using appropriate silica spacers. The dependence of the Raman signal intensity on film thickness was also studied for thicker nanometric films comprising a series of self-assembled organosilane multilayers on bulk silicon and fused silica substrates, and the predicted deviation from linearity in the case of the silicon substrate is experimentally confirmed.

Highly ordered mesoporous organosilica thin films containing functional organic terminal groups covalently bonded to the silica matrix were synthesized by co-condensation of tetraethylorthosilicate (TEOS) and organotriethoxysilane RSi(OEt)3 (R = Cl(CH2)3, CN(CH2)3) in the presence of cetyltrimethylammonium bromide (CTAB) as structure directing agent under acidic conditions. The influence of the nature and concentration of these organic groups on the structure of the thin films is evidenced by Grazing Incidence Small Angle Scattering (GISAXS) and X-ray reflectivity. We show that the introduction of chloropropyl groups strongly affects the structure of these films while cyanopropyl groups weakly perturb it. In the case of the chloropropyl groups, the presence of trans and gauche conformers in the films is clearly evidenced by using micro-Raman spectrometry. Their effects on the phase behaviour versus the concentration are discussed.

The infrared and polarized Raman spectra of the trigonal Li 6 P 6 O 18 ·3H 2 O crystal are reported. The results are analysed using several group theory approaches, in terms of internal and external modes of the highly symmetric P 6 O 18 cyclophosphoric ring and water molecules. Equilibrium geometries and vibrational spectra of P 6 O 18 units, free and in interaction with watermolecules (P 6 O 18 ·3H 2 O) have been determined by ab initio calculations using the basis set 6-31+G(d) of Hartree Fock method. Experimental frequencies and polarisation conditions are remarkably consistent with ab initio calculations. A detailed description of the normal modes of vibration of these systems is presented.

A new route for the elaboration of the polypropylene surface directly modified by 4-amino-4‘-nitroazobenzene (Disperse Orange 3) was studied. The synthesis consists of a cold carbon dioxide-plasma treatment followed by a mixed anhydride reaction and Disperse Orange 3 fixation. The quantity of active acid introduced by the plasma treatment was estimated to be 0.7 groups/nm2 by fluorescence labeling with thionine acetate. The azo-modified surfaces were characterized by Fourier transform infrared, resonance Raman, and X-ray photoelectron spectroscopies. Confocal resonance Raman spectrometry has shown that Soxhlet extraction is effective to eliminate diffused molecules from the material. It was shown that the azo dye molecules are chemically fixed onto the polymer surface.

International audience; We investigated the influence of the coating of maghemite nanoparticles (NPs) with oleic acid and oleylamine molecules on the thermal stability of maghemite and on the gamma -> alpha-Fe2O3 phase transformation. The uncoated maghemite NPs were synthesized by coprecipitation and the coated NPs by thermal decomposition of organometallic precursors. The morphology and size of the coated NPs were characterized by transmission electron microscopy and magnetic and structural properties by Fe-57 Mossbauer and Raman spectroscopies. The phase stability of coated maghemite NPs was examined under in situ laser irradiation by Raman spectroscopy. The results indicate that coated gamma-Fe2O3 NPs are thermally more stable than the uncoated NPs: the phase transformation of maghemite into hematite was observed at 15 mW for uncoated NPs of 4 nm, whereas it occurs at 120 mW for the coated NPs of similar size. The analysis of the Raman baseline profile reveals clearly that the surface coating of maghemite NPs results both in reducing the number of surface defects of nanoparticles and in delaying this phase transition.

We investigated the role of temperature on the carbon steel corrosion under simulated geological conditions. To simulate the effect of temperature increase due to radioactive decay, we conducted batch experiments using Callovo-Oxfordian (COx) claystone and synthetic water formation with steel coupons at 30 °C and 90 °C for 6 months. The corrosion products have been studied by scanning electron microscope/energy dispersive X-ray spectroscopy, X-ray diffraction and micro-Raman spectroscopy. At 30 °C, experiments showed the formation of magnetite and iron sulphide, indicating the activation of sulphate-reducing bacteria. At 90 °C a continuous iron sulphide layer was identified on steel surface due to the reduction by hydrogen of pyrite originating from claystone into pyrrhotite and hydrogen sulphide. Thus, sulphide production may occur even in the absence of microbial activity at high temperature and must be taken into consideration regarding the near-field geochemical evolution.

The structure of a series of alcohol-terminated bifunctional long-tail organosilane films with varying numbers of superimposed monolayers (between 1 and 11), prepared on smooth, hydrophilic silicon substrates by the layer-by-layer self-assembly approach, has been investigated with the purpose of elucidating details of the molecular organization and the intra- and interlayer modes of binding in such films. To this end, experimental results obtained by synchrotron X-ray scattering, micro-Raman, and Fourier transform infrared (FTIR) spectroscopic techniques have been combined and compared. A comprehensive analysis of all data demonstrates that the studied multilayer films consist of stacks of uncorrelated discrete monolayers, the inner molecular order of which is preserved with the growing total number of superimposed layers. Similar to self-assembled films of long-tail silanes with terminal −COOH groups,1 the intermolecular binding in the present films is characterized by partial intra- and interlayer coval...

A new 2-step growth process was developed, combining both the r.f. sputtering and the pyrosol techniques, in which nucleation and growth stages could be partially separated and controlled. Using this refined deposition method, d c ¢ -oriented LiNbO 3 thin films could be successfully grown on (111) silicon and (001) sapphire substrates. Thin film structures have been determined by X-ray diffraction and pole figure analyses. Depositions performed on Si (111) templates led to fiber textures, characteristic of oriented polycrystalline samples. Al 2 O 3 (001) substrates allowed the growth of in-plane oriented layers with two distinguishable variants in the interfacial plane, namely, an aligned variant d 110 ¢ LiNbO 3 //[110]Al 2 O 3 and a 60 °-rotated one.