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In this paper, the effect of the gaseous environment on recrystallization of amorphous paracetamol was investigated. The experiments were conducted with a headspace gas consisting of dry air, dry carbon dioxide, dry nitrogen and humid air in four temperatures ranging from 5 degrees C below onset of T-g to 5 degrees C above onset of T-g. The recrystallization was monitored using Raman spectroscopy and subsequent multivariate analysis. In temperatures below onset of T-g, the presence of oxygen delayed the onset of recrystallization, with an increasing delay with lower temperature. When comparing samples exposed to dry headspace gases, the crystallization was fastest below onset of Tg when exposed to nitrogen. Being an inert gas, nitrogen did not seem to interfere with the molecules allowing them to freely find their inherent arrangement, whereas the presence of oxygen delayed the formation of stabile nuclei. Above onset of T-g, no differences in onset of crystallization was detected between dry gas atmospheres. Amorphous paracetamol crystallized to form II in all measurements and the samples did not reach full crystallinity within the duration of the experiments. The results show that the headspace gas has an effect on nucleation in the amorphous sample.

Poly(lactic acid) or PLA is currently considered as one of the most promising substitutes of conventional plastics, with low environmental impact, especially for food packaging applications. Nevertheless, some drawbacks, such as high permeability to oxygen, are still limiting its industrial applications. The objective of this study was to highly increase the oxygen barrier performance of PLA without compromising its sustainable nature and following the principles of circular economy perspective. Coproducts coming from mill industries, such as wheat gluten proteins (WG), were used to produce PLA-WG-PLA multilayer complexes with improved barrier performance. Different technologies of industrial interest were considered: high-pressure homogenization of WG film forming dispersions, corona treatment of industrial PLA films, wet casting and spin coating for tailoring the WG coating thickness, and hot-pressing for shaping the multilayers. The impact of all these strategies on the properties (surface and bulk) and performances (barrier and adhesion) were investigated on the single constituent layers as well as on the final laminate. The most efficient complex increased more than 20 times (or 2000%) the barrier properties to oxygen and ∼20% the barrier properties to water vapor, considering application conditions (50% relative humidity and 25 °C). The low thickness (∼60 μm) of this complex also matched the requirement for flexible packaging applications. High-pressure homogenization, WG coating thickness, and hot-pressing positively and highly impacted the final properties of the multilayer, while the contribution of corona treatment was limited. This study unambiguously evidenced the potential of PLA-WG-PLA complexes as a valid sustainable substitute for high performing conventional plastics, and it could open an unexplored PLA market opportunity. In addition, it could motivate further investigations on PLA-based laminates for industrial interest, using other biopolymers from agro-industrial waste or byproducts.

Soft polymer colloidal water suspensions are extremely important formulations for industrial applications such as water-based environmental-friendly coatings, paints, and adhesives. Homogeneity of the final coating at the micrometer and nanoscale is a crucial factor for optimal coating performance, such as barrier properties against solvent permeation. Here, we investigated the remnant nanostructure in slot-die-coated micrometer-sized thick clear coating films (clearcoats) of three different waterborne polymer colloids (pure soft, pure hard, and soft/hard multiphase), commonly utilized as primers in paint formulations [Mader et al. Prog. Org. Coat. 2011, 71, 123-135], using variable-angle grazing incidence small-angle X-ray scattering (GISAXS) complemented with cross-sectional atomic force microscopy (cs-AFM). After complete macroscopic drying, the coating films exhibit the presence of residual nanostructure with characteristic distance (d*) smaller than the original particle size and even smaller (<< d*) heterogeneity dimensions. These nanostructural heterogeneities (i) develop due to partial particle coalescence, (ii) are preferentially located close to the air-film interface and (iii) demonstrate the tendency to align perpendicular to the air-film interface, implying vertical gradient in hydroplasticization effects having occurred earlier during film formation. The extent and size of the nanostructural heterogeneities, driven by the slot-die coating application, strongly depend on the polymer chemistry (glass transition temperature, T-g) and the colloidal architecture. Last, solvent exposure has a significant impact on the nanostructure, causing the removal of these heterogeneities and leading to a more strongly coalesced film.

Vitrimers are permanently cross-linked organic polymers that can be reshaped, molded, and recycled without loss of network integrity. Herein, we report poly(thioether) networks, prepared through a straightforward thiol-ene photopolymerization, that can be turned into catalyst-free vitrimer materials by partial alkylation of the thioethers (1-10%) to the corresponding trialkylsulfonium salts. Based on a classical S(N)2-type substitution, the resulting polyionic networks can be reshaped upon heating via swift transalkylation reactions. This novel exchange reaction for the design of vitrimers was studied both on low MW model compounds as well as on a material level. In addition, we demonstrated the recycling of these networks without significant loss of mechanical properties.

Although nanostructured phase-change materials (PCMs) are considered as the building blocks of next-generation phase-change memory and other emerging optoelectronic applications, the kinetics of the crystallization, the central property in switching, remains ambiguous in the high-temperature regime. Therefore, we present here an innovative exploration, of the crystallization kinetics of Ge2Sb2Te5 (GST) nanoparticles (NPs) exploiting differential scanning calorimetry with ultrafast heating up to 40 000 K s(-1). Our results demonstrate that the non-Arrhenius thermal dependence of viscosity at high temperature becomes an Arrhenius-like behavior when the glass transition is approached, indicating a fragile-to-strong (FS) crossover in the as-deposited amorphous GST NPs. The overall crystal growth rate of the GST NPs is unraveled as well. This unique feature of the FS crossover is favorable for memory applications as it is correlated to improved data retention. Furthermore, we show that methane incorporation during NP production enhances the stability of the amorphous NP phase (and thereby data retention), while a comparable maximum crystal growth rate is still observed. These results offer deep 'insight into the crystallization kinetics of nanostructured GST, paving the way for designing nonvolatile memories with PCM dimensions smaller than 20 nm.

International audience; Poly(lactic acid) (PLA) is the most traded biodegradable and biobased material. It is largely used as ecofriendly substitute of conventional plastics. Nevertheless, one of the main limiting factors is its water sensitivity. PLA reacts with water and is hydrolyzed during time, which determines its performance. Limited information related to the hydrolysis mechanism driven by water in vapor state is available in scientific literature. Literature is mainly focused on the effects of water in liquid state. This lack of information is of significant importance, since PLA interacts with water in both phases. This work was aimed to give a full depiction of the chemical and physical changes of PLA in a large range of relative humidity environments (from 50 to 100% RH) and in contact with liquid water. This research clearly showed that the stability of PLA was influenced not only by the chemical potential of water molecules, but also by their physical state due to a different behavior of degradation products. From a practical point of view, the findings of this study can be used as strong scientific basis for giving recommendations about the use of this material in its applications as packaging or mulch films.

The influence of nanohydroxyapatite on the glass transition region and its activation energy, as well as on the tribological and mechanical properties of polyoxymethylene nanocomposites, was investigated using DMA, TOPEM DSC, nanoindentation, and nondestructive ultrasonic methods. It was found that the glass transition for unmodified POM was in the lower temperature range than in POM/HAp nanocomposites. Moreover,ΔCpand activation energy were larger for POM/HAp nanocomposites. Friction coefficient was higher for POM/HAp nanocomposites in comparison to both POM homopolymer and POM copolymer. Simultaneously, the indentation test results show that microhardness is also higher for POM/HAp nanocomposites than for POM. From ultrasonic investigations it was found that the highest values of both longitudinal and transverse propagation waves and Young’s and shear modulus for POM homopolymer (DH) and POM copolymer T2H and their nanocomposites can be attributed to their higher degree of crystallinity in comparison to UH copolymer. Moreover, for POM/HAp nanocomposites with 5% of HAp, ultrasonic longitudinal wave velocity was almost constant even after 1000000 mechanical loading cycles, evidencing an enhancement of mechanical properties by HAp nanoparticles.

International audience; Acid-driven multiphase chemistry of isoprene epoxydiols (IEPOX), key isoprene oxidation products, with inorganic sulfate aerosol yields substantial amounts of secondary organic aerosol (SOA) through the formation of organosulfur compounds. The extent and implications of inorganic-to-organic sulfate conversion, however, are unknown. In this report, we demonstrate that extensive consumption of inorganic sulfate occurs, which increases with the IEPOX-to-inorganic sulfate concentration ratio (IEPOX:Sulf inorg), as determined by laboratory measurements. Characterization of total sulfur aerosol observed at Look Rock, Tennessee, from 2007-2016 shows that organosulfur mass fractions will likely continue to increase with ongoing declines in anthropogenic Sulf inorg , consistent with our laboratory findings. We further demonstrate that organosulfur compounds greatly modifies critical aerosol properties, such as acidity, morphology, viscosity, and phase state. These new mechanistic insights demonstrate that changes in SO 2 emissions, especially in isoprene-dominated environments, will significantly alter biogenic SOA physicochemical properties. Consequently, IEPOX:Sulf inorg will play an important role in understanding historical climate and determining future impacts of biogenic SOA on global climate and air quality.

Inulin, a fructan-type polysaccharide, consists of (2 -> 1) linked beta-D-fructosyl residues (n = 2-60), usually with an (1 2) alpha-D-glucose end group. The applications of inulin and its hydrolyzed florin oligofructose (n = 2-10) are diverse. It is widely used in food industry to modify texture, replace fat or as low-calorie sweetener. Additionally, it has several applications in other fields like the pharmaceutical arena. Most notably it is used as a diagnostic agent for kidney function and as a protein stabilizer. This work reviews the physicochemical characteristics of inulin that make it such a versatile substance. Topics that are addressed include morphology (crystal morphology, crystal structure, structure in solution); solubility; rheology (viscosity, hydrodynamic shape, gelling); thermal characteristics and physical stability (glass transition temperature, vapor sorption, melting temperature) and chemical stability. When using inulin, the degree of polymerization and processing history should be taken into account, as they have a large impact on physicochemical behavior of inulin. (C) 2015 The Authors. Published by Elsevier Ltd.

Strength concept, which is based on the Williams-Landel-Ferry (WLF) model, was developed using mixed structured powders containing amorphous and crystalline components. At the present study, semi crystalline trehalose powders with various (100:0; 80:20; 60:40; 40:60; 20:80) amorphous to crystalline ratios were analyzed. Amorphous components were prepared from water solution by freeze-drying. Strength analysis, which included water sorption, differential scanning calorimetry, dynamic mechanical analysis and microscopy, was applied. The results indicated that water content significantly decreases glass transition (similar to 100 degrees C) and alpha-relaxation temperatures (similar to 90 degrees C) as well as structural strength parameter (similar to 10 degrees C), while, the effect of crystalline component is less pronounced. This study can be used in processing and characterization of various partially crystalline food products including nutritional formulations and infant formulas.

The techno-functional properties of soy, lupine and rapeseed protein concentrates (SPC, LPC and RPC, respectively) in fish feed were evaluated relative to fish meal (FM). The effects were studied using a shear cell device and an extruder with emphasis on the added moisture content. Six diets were formulated: an SPC-based diet with 300 g SPC kg −1 , diets containing 100 and 200 g LPC kg −1 or 100 and 200 g RPC kg −1 and an FM-based diet with 450 g FM kg −1 . Each diet was extruded with an added moisture content of 29%, 25% and 22% of the mash feed rate. It was found that the technological properties of LPC closely resemble FM, being high solubility, low water-holding capacity (WHC) and low paste viscosity. The LPC 100 and 200 g kg −1 diets could be extruded at 22% moisture, which gives an extrudate with reduced drying requirements. In addition, less specific mechanical energy was needed for extrusion. In contrast, both SPC and RPC have high WHC and paste viscosity. This explains the higher feed moisture required during extrusion. The properties of the feeds containing RPC could be well within the ranges acceptable for commercial fish feed use at even higher moisture content compared with SPC. The results of the extrusion trials confirmed the observations made from the shear cell device. Thus, the shear cell device can be used to study processing conditions that are close to extrusion conditions.

The mechanism of the enzymatic polymerization of amylopectin analogs with phosphorylase b and glycogen branching enzyme is very intriguing. Recently, size exclusion chromatography with multi-detection of enzymatically synthesized amylopectin analogs in combination with MALDI-ToF MS analysis of enzymatically debranched analogs was used to solve parts of the molecular mechanism of analog's enzymatic polymerization. In this work dynamic light scattering (DLS), AFM and cryo-TEM, respectively were used to determine structural characteristics of the same analogs. The results were compared with SEC analyses. The presented analyses in this work fully agreed with the recently made observations and confirmed the changes in the architecture of the synthesized polysaccharide due to the change of enzymatic polymerization mechanism. Furthermore, we showed that the synthetic amylopectin analogs are stable to retrogradation at 4 degrees C if the main side chain length is no longer than 12 glucose units and that they have mostly fluid-like behavior in the form of 20% suspensions.

Retrogradation of amorphous thermoplastic starch (TPS) films obtained by compression moulding of spray dried amorphous powder was investigated. The aim of the work was to study the influence of malto-oligosaccharide molecular weight, i.e. dextrose equivalents (DEs), on the performance of the powders and the films. Amorphous TPS films were obtained, irrespective of the additive used. At a relative humidity (RH) of 0% and 50% all samples maintained their amorphous nature while at RH100% retrogradation was suppressed for all formulated starch films. It is shown that the rate of moisture uptake, and as a consequence, the rate of retrogradation, depends on the molecular weight of the additive. FT-IR and TGA measurements proved a more effective interaction of starch with low molecular weight additives such as maltose and glucose syrup (DE 38.2) than for the higher molecular weight maltodextrine (DE 19.1). (c) 2013 Elsevier Ltd. All rights reserved.

This study investigated the influence of pre-crystallisation and water plasticization on flow properties of lactose/whey protein isolate (WPI) solids systems. Powder characteristics of lactose/WPI mixtures with different amounts of α-lactose monohydrate (1.01%, 11.18%, 29.20%, and 46.84%, w/w) were studied. Dairy powders with higher amounts of crystalline lactose showed larger tapped bulk density and particle density. Morphological characteristic study indicated that dairy solids with higher crystallinity had less rounded shape and rougher surface. Increasing protein content or crystalline lactose content could decrease the molecular mobility of dairy solids. Flow function tests indicated that dairy solid with 11.18% crystallinity was more easy-flowing than lactose/WPI mixtures with 1.01%, 29.20% and 46.84% crystallinity at 0% and 44% relative humidity (RH) storage conditions. Furthermore, dairy solids with higher amount of crystalline lactose showed better resistance to develop cohesive at high RH storage conditions. The friction angle of dairy solid with 1.01% crystallinity increased with increasing water content, while friction angles of lactose/WPI mixtures with higher crystallinity decreased with increasing water content.

International audience; By specifically labeling leucine/valine methyl groups and lysine side chains "inside" and "outside" dynamics of proteins on the nanosecond timescale are compared using neutron scattering. Surprisingly, both groups display similar dynamics as a function of temperature, and the buried hydrophobic core is sensitive to hydration and undergoes a dynamical transition.

The dynamics of the herringbone structure formation have been studied in a monobromo hexa-peri-hexabenzocoronene derivative by infrared spectroscopy and complementary techniques. Selective probing of the vibration modes corresponding to the aromatic core and the alkyl chains, allowed investigation of their role in the phase transformation dynamics over an extraordinarily broad time-window (1-10(5) s). Identical kinetics were found suggesting that both the core and the alkyl chains simultaneously drive the system from the undercooled liquid crystalline to the crystalline phase with the herringbone structure. Journal of Physical Chemistry B

We report detailed structural investigations, by synchrotron X-ray reflectivity (XRR), grazing incidence diffraction (GID), and space-resolved grazing incidence X-ray-induced fluorescence (GIXF), on the structure of molecular layers of polyaniline (PANI) that can be converted from insulating to conducting state simply by doping. We first address the simpler, but more intriguing, system, i.e., a floating monolayer of PANI on different subphases, for which we found a typical thickness of 28(1) A, not much affected by the doping process. For the doped film we also found an internal lateral structure, with in-plane spacing of 3.5 A-albeit with a small coherence of 3-4 repeat units only-compatible with face-to-face interchain stacking of phenyl rings, in agreement with the literature. By GIXF we could confirm the crucial role of Cl(-) intercalation in the doping process of the PANI film: under doping conditions (0.1 M HCl subphase) the Cl(-) intake is 8 times larger than in nondoping conditions (0.1 M KCl subphase). Multilayers transferred onto solid substrate were studied also as a function of the applied voltage, as this system constitutes the core of an electrochemically controlled device whose strongly nonlinear characteristic make it useful for applications to adaptive networks for complex information processing. By the application of an electrostatic field of 140 V/m, Cl ionic migration was observed confined to the polymeric film surface.

International audience; A series of cholinium cation-based bioionic liquids (BioILs) were synthetized with the aim of screening their performance as potential plasticizers of thermoplastic starch. To synthesize these BioILs, two easy and fast synthetic routes were selected: an ion exchange reaction, direct and economical, and a two-step acid-base reaction. Most of these BioILs allowed efficient plasticization of starch by film casting. The structure of the anion used significantly influences the thermo(hygro) mechanical and recrystallization behavior, making it possible to modulate the properties of the final material.

It is well accepted that adding nanoparticles (NPs) to polymer melts can result in significant property improvements. Here we focus on the causes of mechanical reinforcement and present rheological measurements on favourably interacting mixtures of spherical silica NPs and poly(2-vinylpyridine), complemented by several dynamic and structural probes. While the system dynamics are polymer-like with increased friction for low silica loadings, they turn network-like when the mean face-to-face separation between NPs becomes smaller than the entanglement tube diameter. Gel-like dynamics with a Williams–Landel–Ferry temperature dependence then result. This dependence turns particle dominated, that is, Arrhenius-like, when the silica loading increases to ∼31 vol%, namely, when the average nearest distance between NP faces becomes comparable to the polymer’s Kuhn length. Our results demonstrate that the flow properties of nanocomposites are complex and can be tuned via changes in filler loading, that is, the character of polymer bridges which ‘tie’ NPs together into a network., Partial support has been provided by the EU FP7 (ETN Supolen GA-607937, Infrastructure ESMI GA-262348) and the Greek General Secretariat for Research and Technology (Thalis-380238 COVISCO). M.R. acknowledges financial support from the National Science Foundation under grants DMR-1309892, DMR-1436201 and DMR-1121107, the National Institutes of Health under grants P01-HL108808 and 1UH2HL123645 and the Cystic Fibrosis Foundation. D.Z., S.G., R.H.C. and S.K.K. gratefully acknowledge the National Science Foundation grant DMR-1408323 for financial support.

The production of bioplastics directly from wheat flour has been demonstrated to be reliable, but scarce knowledge is available on how flour characteristics may affect the performance of thermoplastic films. In this work, we first established the most suitable recipe and process for the production of extruded films and then we used eight single-cultivar wheat flours with different baking technological properties to assess how they affect the mechanical properties of thermoplastic films. The results have shown that flours from soft grain cultivars offered more rigid and deformable films than flours from hard grain cultivars. For similar hardness, the alveographic P/L ratio of the dough was inversely related to rigidity and directly related to deformability of plastic films, while the deformation energy of the dough (W) played a role only for great differences of it. The subsequent fabrication of blends between each of the flours that yielded the best film properties and polycaprolactone (PCL) at different proportions indicated that a wheat flour/PCL ratio (TWF/PCL) of 75/25 offered the most suitable films for further application. Our results are likely to be useful for improving the plasticization of flour, in that selection of wheat flours could be tailored on the properties desired for the bioplastic films.

International audience; Poly (butyl methacrylate-co-methacrylic acid) copolymers/calcium carbonate (CaCO3) composites were synthesized by radical polymerization. Ca2+ cationic sites, present at the CaCO3 surface, in interaction with carboxylate groups from polymer chains structured the material, particularly above the glass transition temperature. The composites were studied by transmission electron microscopy, X-ray diffraction, and dynamic mechanical analysis. Multiplets and clusters were detected. The material's behavior is principally controlled by the methacrylic acid (MA) content in the copolymer chain and CaCO3/MA ratio. Under well-defined conditions, ionic cross-linked materials were obtained.

Electrostatic separation based on different tribo-electric charging behaviours of components has emerged as a novel, sustainable dry fractionation process. This study aims to characterise charging behaviour of single-component particles in nitrogen gas flowing through aluminium tubes. Experiments were carried out with polystyrene (PS) particles and wheat gluten as model particles. Results indicated that specific charge increased linearly with gas velocity up to 28 m/s for both materials. It was found that surface charge densities of different-sized PS particles overlapped for laminar gas flow, whereas for higher stronger gas flow rates, surface charge density of the smallest particles deviated from that of larger particles. Specific charge of PS particles increased linearly with increasing tube length from 125 to 225 mm. Additionally, charging of PS particles was unaffected by relative humidity (RH) of gas; however, specific charge of wheat gluten decreased for RH > 80%. Concluding, these results provide insight in critical parameters affecting charging behaviour, thus facilitating the development of electrostatic separation processes to fractionate food ingredients.

To develop n-type processable polymeric materials for photovoltaic applications, a series of polymers was synthe- sized by grafting fullerene C60 onto polystyrene (PS). Grafted polymers were studied and compared with PS:fullerene blends. Electronical and electrical properties were first measured to define the minimal amount of C60 required for solar cells applica- tion. Then, thermal properties and rheological behavior of grafted polymers were analyzed to determine whether they could be processed from the melt. A throughout experimental study revealed that C60-grafted polymers exhibit two thresholds. The first threshold at 3-4 vol % (detected by electrical conductiv- ity, electron mobility, and melt viscosity measurements) is asso- ciated to the percolation of C60 molecules. The second threshold (evidenced by glass transition and melt viscosity measurements and confirmed by optical and atomic force micrograph observa- tions) at about 12-13 vol % is assumed to be related to the for- mation of C60 aggregates. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 000: 000-000, 2012

Although many polymer nanocomposites have been described, the impact of colloidal nanoparticles (NPs) used as fillers on the thermal behavior of the matrix has been described only in a few cases. Here we apply thermal methods to inquire the effect of organically capped Ag and Au particles on poly(tert-butyl acrylate) (PtBA) based composites. The nanocomposites have been prepared by ex situ and in situ methods; in the former method the metal NPs were isolated from the respective colloids and then blended into cast films obtained from tetrahydrofuran solutions of the polymer; while in the latter the in situ polymerization of tert-butyl acrylate using miniemulsions was carried out in the presence of homogeneously dispersed colloidal NPs. The nanocomposite materials were then characterized by differential scanning calorimetry (DSC) to assess the effect of colloidal metal NPs on the glass transition temperature of the polymer (T-g) namely by considering their chemical nature, average particle size, and metal load. Although similar effects have been observed when Au or Ag NPs were employed as nanofillers, it was also found that the T-g depends on the NPs morphological characteristics and on the preparative method employed to obtain the nanocomposite. This research also highlights the relevance of the surface chemistry of colloidal nanofillers on the thermal behavior of the respective composites. (C) 2013 Elsevier B.V. All rights reserved.

Experimental results by Fisher et al. [Faraday Discuss. Chem. Soc. 1979, 68, 26] showed the existence of local orientational correlations of segments of the n-alkane molecules in the liquid state. Since the estimated correlation volume is below 10(3) angstrom(3), molecular dynamics simulations appear to be a suitable method for their identification and characterization. We used molecular dynamics to fully characterize short-range order in polyethylene melts. The characterization started by identifying sequences of aligned segments in chains, each one having at least one Kuhn monomer in length. Afterward, a search was made for interactions of a tagged aligned chain segment with others fulfilling the same condition, laying within a limiting separation distance (18 angstrom) and making a limiting orientation angle (40 degrees). When, at least, four interactions are counted, a short-range ordered region is defined. Chain placement in these regions has similarities to that of the unit cell at the solid phase, although with different separation distances and angle. Overall, short-range order resembles a dynamic uniaxial nematic phase, the local order parameter increasing with the chain length in agreement with experimental results. Segments at the ordered regions persist over time, for times longer than the Rouse relaxation time of the chain. Those in random conformational sequences between the ordered regions have a mass distribution in agreement with the Flory distribution, with a number-average value comparable to experimental results for the molecular mass between entanglements.

The properties and morphologies of blends of poly(butylene succinate) (PBS) and glycerol-plasticized thermoplastic starch (TPS) were investigated. Bis-pyrrolidone-type monomers (obtained from itaconic acid) with various sizes of alkylidene spacers were synthesized and polycondensed with various diamines. The resultant polycondensates were used as compatibilizers to improve interfacial adhesion in PBS/starch blends. The presence of long hydrophobic -CH2- sequences in the compatibilizers improved the elongation-at-break during tensile tests. The enhanced compatibilization induced by these copolymers is presumably because of the hydrophobic interaction with PBS and the hydrophilic hydrogen bonding with starch. The uncompatibilized TPS/PBS exhibited a dispersed morphology with blends of low- and high-starch content, whereas the compatibilized blends presented a co-continuous phase. Bis-pyrrolidone-type monomers (obtained from itaconic acid, which is a renewable chemical identified in the top 12 value-added chemicals from biomass) with alkylidene spacers of variable size were synthesized and polycondensed with various diamines. The resulting polycondensates were used as compatibilizers to improve interfacial adhesion in poly (butylene succinate) (PBS)/plasticized starch blends. The interfacial adhesion between PBS and plasticized starch was improved using these polycondensates.

Nanocomposite films were prepared by a thermo-mechanical process from wheat gluten (WG) and unmodified montmorillonite (MMT). The present work aims at predicting the relationships between the decrease in relative diffusivity of liquid water and the structure of the nanocomposite films, from in situ evaluation of the MMT size aspect ratio and volume fraction, and by using a simple tortuous path mathematical model. The modelling approach first allowed predicting and validating the tortuosity effect of MMT particles on liquid water transport properties of WG-based films. In spite of a well-exfoliated nanocomposite structure, the liquid water diffusivity in WG-based films can at best be decreased by a factor of 2 with this type of clay nanoparticle, which was in agreement with the Bharadwaj model predictions. This study underlines the necessity to achieve a totally exfoliated nanocomposite structure, and above all, to select layered silicates displaying higher size aspect ratio values in order to efficiently improve water barrier properties of WG-based nanocomposite films. Furthermore, the extremely complex structure of nanocomposite materials makes detailed morphological studies often difficult, time and cost consuming. (c) 2012 Elsevier Ltd. All rights reserved.

International audience; In this work, we aimed at studying formulation and design of powders by modified wet compression method. In order to focus only on the role of the liquid binder in the mechanical cohesion of compacts, glass beads were used as model particles because they do not deform or fragment at the compression pressure used (35kN). The three different binders studied were sugars: fructose, glucose and saccharose, used as solutions. Therefore, compacts were stored at controlled conditions until reaching water activity equilibrium at a fixed temperature of 25 degrees C. Then, the tensile strength of the compacts was determined using a Brazilian test. It was found to be dependent on the water activity. Critical values of Aw were measured (A(w) = 0.23 for the fructose, A(w) = 0.33 for the glucose, and A(w) = 0.44 for the saccharose), beyond which the glass transition phenomenon of the sugars appeared, and resulted in a sharp drop in the mechanical strength of the compacts. The classification of the sugars according to their respective glass transition temperature (Tg(fructose) < Tg(glucose), < Tg(saccharose)) permitted to confirm the role of the glass transition of the sugars as binders in the mechanical resistance of the compacts. Finally, sorption isotherms of the sugars coupled to the tensile strength results showed that the main parameter for predicting mechanical strength of the compact was the amount of sorbed water by the sugar, regardless to his nature.

International audience; The influence of kaolinite content within a plasticized starch matrix on the glass transition and decomposition temperatures, water uptake, transparency and UV-vis blocking is reported. Exfoliation of the kaolinite clay within the composite is enhanced when previously intercalated with DMSO. The DMSO-intercalated kaolinite brings in advantages for the clay dispersion within the polymer matrix, the transparency and the water uptake. The transparency of the films is better preserved when DMSO intercalated kaolinite is used and a clay load between 2% and 6%, leads to a significant reduction of the UV light transmission.

We describe the water activity of meat, being a mixture of proteins, salts and water, by the Free-Volume-Flory–Huggins (FVFH) theory augmented with the equation. Earlier, the FVFH theory is successfully applied to describe the thermodynamics to glucose homopolymers like starch, dextrans and maltodextrins. We have estimated parameter values from sorption isotherms of unsalted, lean meat products and model proteins like elastin and gelatin. These parameter values are quite similar to those found for glucose homopolymers. Moist meat products are also characterized with a water holding capacity, which we can describe with the Flory–Rehner theory. Subsequently, we have been able to predict very accurately the sorption isotherms of salted meat products and gelatin gels. Hence, the thermodynamics of foods can be described without the use of the controversial concept of bound/unfreezable water. Comparison of FVFH theory combined with Flory–Rehner theory to concentrated systems shows that the theory contains terms that are double counting for elastic effects – which makes us conclude that the validity of the Flory–Rehner theory is restricted to the (semi)-dilute regime. A complete thermodynamic description is proposed via mathematical matching of the FVFH and Flory–Rehner theory.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; The effect of water activity on anthocyanin degradation and non-enzymatic browning (NEB) indices was determined in a blackberry juice system heated to high temperature. Blackberry juice samples mixed with quartz sand at three different water activities (a(w) of 0.34, 0.76 and 0.95) and having the same concentration of anthocyanins (51 +/- 4 mg 100g(-1) WB) were heated in a hermetically sealed reactor under non-isothermal conditions (100 to 140 degrees C). Reaction kinetics were well-represented by first-order reaction models. A non-isothermal method was used for the identification of kinetic parameters, and the confidence interval for each parameter was determined via Monte-Carlo simulations. The estimated parameters revealed an increase in the anthocyanin degradation reaction rate constant (k(ref)) from 0.9 to 3.5 x 10(-3) s(-1) as the water activity decreased from 0.99 to 0.34. The corresponding activation energies (Ea) for anthocyanins and NEB index were modified to a lesser extent by variations in water activity. Hence, the reduction of water activity had a negative effect on anthocyanin stability at high temperatures. (C) 2012 Elsevier Ltd. All rights reserved.

We present a detailed comparison of the segmental and chain dynamics of an atactic monodisperse polystyrene (molecular weight 1800 g/mol) (a-PS) studied by hierarchical multiscale molecular dynamics (MD) simulations, with an atactic polystyrene (M-n = 1644 g/mol, polydispersity index 1.14) investigated by dielectric spectroscopy, rheology and differential scanning calorimetry. The MD simulations, performed at three temperatures (403, 433, and 463 K), can capture the temperature dependence of the segmental and terminal relaxations in good quantitative agreement with experiment, taking into account the uncertainties in the development of the atomistic force field. In addition, ring and backbone segmental dynamics are studied by analyzing time-correlation functions for various bond vectors in the monomer level. MD simulations at elevated pressures (40 and 60 MPa) were also in good agreement with experiments probing the pressure-dependent glass temperature. Macromolecules

The low-frequency vibrational dynamics of chicken hen egg-white lysozyme were investigated using Raman spectroscopy and low-temperature calorimetry. An amorphous-like behaviour of low-frequency dynamics was observed in this protein. By using inelastic light scattering data and resorting to a fitting procedure, the low-temperature specific heat trend was theoretically reproduced, confirming that, as in disordered systems, the same low-energy excitations give rise to the observed anomalies in low-frequency vibrational and low-temperature thermal properties. A further study of polarised and depolarised Raman spectra has allowed us to infer information about the symmetry of these modes. The frequency dependence of the light–vibrational coupling constant has also been analysed.

Water sorption of gluten and wheat starch films as a function of water activity was studied using gravimetric step-change sorption experiments. Films of different thicknesses were used with the aim to vary the characteristic diffusion time and to get insights in the contribution of the polymer-chain rearrangement in the sorption behaviour. It is shown that both starch and gluten are in the glassy state for a water activity aw below 0.9. From comparison of the dynamical sorption curves with a Fickian diffusion model, it is shown that water diffusion in gluten films seems Fickian for aw 0.7, while for starch films, non-Fickian sorption behaviour is observed for aw > 0.1. The results show that polymer-chain rearrangement and the stress built up in the matrix play an important role in the sorption dynamics of these films. Even when the material is in the glassy state matrix relaxation phenomena play a role in the sorption behaviour of starch and gluten.

The doping-induced conductivity transitions in molecular layers of polyaniline have been studied by monitoring the correlated optical and spectroscopic changes using spectroscopic and single wavelength extinction ellipsometry, also in total internal reflection mode (TIRE), together with reflection spectrometry. The measurements were performed on deposited multilayers as well as on a Langmuir monolayer at the air-water interface, as a function of acidic doping. We found that the characteristic spectroscopic features of conducting and insulating polyaniline persisted down to the single layer, both in the solid state and at the air-water interface. We also investigated in real time the modulation of conductivity induced by the intercalation of Li ions in the polyaniline film, by a combination of time-resolved ellipsometry and reflectivity spectra measurements. In this case, the enhanced sensitivity provided by the TIRE geometry, combined with the relatively fast time scale accessible by the single wavelength ellipsometry, allowed us to follow in detail in real time the doping/dedoping process.

We report Small Angle X-ray Scattering (SAXS) measurements performed on samples of carboxy-myoglobin (MbCO) embedded in low-water trehalose glasses. Results showed that, in such samples, "low-protein" trehalose-water domains are present, surrounded by a protein-trehalose-water background; such finding is supported by Infrared Spectroscopy (FTIR) measurements. These domains, which do not appear in the absence of the protein and in analogous sucrose systems, preferentially incorporate the incoming water at the onset of rehydration, and disappear following large hydration. This observation suggests that, in organisms under anhydrobiosis, analogous domains could play a buffering role against the daily variations of the atmospheric moisture. The reported results are rationalized by assuming sizably different protein-matrix coupling in trehalose with respect to sucrose, analogous to the one suggested for the photosynthetic reaction centre from Rhodobacter sphaeroides (F. Francia et al., J. Am. Chem. Soc., 2008, 130, 10240-10246).

Nanocomposites based on attapulgite clay and shape-memory polyurethane were fabricated by mechanical mixing. The mechanical properties of samples were evaluated using a micro-indentation tester. The untreated commercial attapulgite clay resulted in a significant decrease in glass transition temperature and hardness of the nanocomposite due to the presence of moisture as well as the clay's amorphous structure and surface hydroxyl groups. The attapulgite nanoparticles were heat-treated at 850 degrees C, which resulted in crystallization of the particles and formation of layered attapulgite structure. The hardness of the nanocomposites composed of the heat treated clay powder dramatically increased as a function of clay content, which is attributed to the homogeneous dispersion of the nanofillers in the polymer matrix and strong filler-polymer interactions. Shape recovery of indentations has been demonstrated upon heating. (C) 2009 Elsevier Ltd. All rights reserved.

Isothermal physical ageing experiments were performed by differential scanning calorimetry to probe the enthalpy relaxation in a methacrylate copolymer carrying azobenzene mesogenic side groups. Further evidence of the ability of the configurational entropy model developed by Gomez Ribelles in describing the structural relaxation mechanism of polymers is provided. The trend of the equilibrium structural relaxation time was also determined as a function of the reduced temperature T-g/T. The comparison of the aging dynamics of the copolymer with those of previous analogous copolymers containing different amounts of azobenzene counits allowed us to highlight effects of the liquid-crystalline nematic order on the properties of structural relaxation.

In order to clarify the role of hard confinement on protein dynamics, elastic and quasi-elastic neutron scattering experiments have been performed on ferric horse myoglobin in two different systems: the protein embedded in a porous silica matrix, and the corresponding hydrated protein powder. Elastic data have been analysed using two different models (dynamical heterogeneity and anharmonic double-well potential) that take into account deviations of elastic intensity from Gaussian behaviour. The profile of quasi-elastic spectra has been approximated by a combination of Lorentzian and Gaussian components. Comparison between the data relative to the two different samples indicates that geometrical confinement within the matrix plays a crucial role in protein dynamics and conformational stability, the effect of sol-gel encapsulation being essentially a reduction of large scale protein motions (alpha-relaxation) likely related to the slowing down of solvent confined diffusion. (C) 2007 Elsevier B.V. All rights reserved.

The poly(methyl methacrylate) (PMMA) segmental dynamics in miscible blends of PMMA with poly(ethylene oxide) (PEO) were studied as a function of pressure by means of dielectric spectroscopy (DS). This facilitates a test of the predictions of the self-concentration model proposed by Lodge and McLeish, at elevated pressures. We find that pressure increases the glass temperature and slows down the segmental dynamics but does not affect the length scale or the self-concentration associated with the dynamic glass transition. This is in agreement with the expectations borne out from the model. Macromolecules

The real and imaginary components of the complex heat capacity, C(p) (') and C(p) ("), and C(p,app) have been measured in real time during the linear chain polymerization on 12 K/h heating of six different (partially) polymerized states of a stoichiometric mixture of cyclohexylamine and diglycidyl ether of bisphenol A. Their C(p,app) shows a sigmoid shape rise with different onset temperatures T(onset), which is followed by a deep exotherm as the viscosity decreases and further polymerization occurs at different rates. The rates of their enthalpy decrease on polymerization determined by subtracting C(p) (') from C(p,app) differ but C(p) (') and C(p,app) of their final states are the same. The relaxation time increases with polymerization and decreases with an increase in T. C(p) (') rises in a sigmoid shape manner, and C(p) (") shows a peak when the relaxation time of the polymerized state is equal to the inverse of the temperature modulation frequency, whether polymerization occurs or not. The unrelaxed or vibrational heat capacity C(p,vib) of the polymers at T>T(onset) is close to C(p) of their glassy state at T

Using elastic neutron scattering measurements we have investigated the picosecond dynamics of dry and hydrated powders of DNA in the double-stranded (dsDNA) and single-stranded (ssDNA) state in the temperature range from 20 to 300 K. The extracted mean square displacements of DNA hydrogen atoms exhibit an onset of anharmonicity at around 100 K. The dynamics of the hydrated samples shows a further anharmonic contribution appearing at a temperature T-d=230-240K. Such dynamical behaviour is similar to the well-studied dynamical transition found in hydrated protein powders. The mean square displacements of dsDNA and ssDNA are practically superimposed in tile whole temperature range for both dry and hydrated samples. This suggests that the DNA local mobility in the picosecond timescale does not depend on the single- or double-stranded conformation.

The steady state fluorescence (SSF) technique was used to study the sol-gel transition for the solution free radical crosslinking copolymerization of N-isopropyl acrylamide (NIPA), with N,N'-methylenebis (acrylamide) (BIS) as crosslinker in the presence of ammonium persulfate (APS) as an initiator. Pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt, HPTS) was used as a floroprobe for monitoring the polymerization. Pyranine molecules start to bind to NIPA polymer chains upon the initiation of the polymerization, thus the spectra of the bonded pyranines shift to the shorter wavelengths. The get fraction exponent beta and the weight average degree of polymerization exponent gamma' agree best with the mean-field (Flory-Stockmayer) results near the gel point for various crosslinker contents. Publisher's Version Q3 WOS:000243586600006

Electron spin resonance spectroscopy has been employed to analyze the probe rotational dynamics in a narrow distribution poly(methyl acrylate) melt. Dynamic regions have been found in the investigated temperature range and the coupling of the probe dynamics to the main and secondary polymer relaxations has been studied. The temperature dependence of the shear viscosity has been also measured, and, in the supercooled state of the host, it has been used to reveal the effects on the probe dynamics of both the local stiffness of the polymer and the occurrence of cooperativtity and dynamic heterogeneities in the matrix. Below T, the rotational dynamics follows activated regimes. (c) 2006 Elsevier B.V. All rights reserved.

The dynamics of lysozyme in the picosecond timescale has been studied when it is in dry and hydrated powder form and when it is embedded in glycerol, glycerol–water, glucose and glucose–water matrices. The investigation has been undertaken through elastic neutron scattering technique on the backscattering spectrometer IN13. The dynamics of dry powder and embedded-in-glucose lysozyme can be considered purely vibrational up to 100 K, where the onset of an anharmonic contribution takes place. This contribution can be attributed to the activation of methyl group reorientations and is described with an Arrhenius trend. An additional source of anharmonic dynamics appears at higher temperatures for lysozyme in hydrated powders and embedded in glycerol, glycerol–water and glucose–water matrices. This second process, also represented with an Arrhenius trend, corresponds to the so-called protein dynamical transition. Both the temperature where such a transition takes place and the magnitude of the protein mean square displacements depend on the environment. The dynamical response of the protein to temperature is put in relationship with its thermal stability.

We present a study of photoinduced transitions occurring in a low ${T}_{G}$ liquid crystalline polymer containing the azobenzene group in the side chain. The structural phase of this material can be optically switched between the glassy, nematic and isotropic states. We show the equivalence of light and temperature in causing these effects, promoting this material as a tool in the investigation of structural relaxation at transitions in confined geometry and fast temperature variation as in the case of the optically induced quenching that we report. The results allow us to propose also alternative writing methods for the application of these materials to high density optical memories.

The rotational dynamics of the spin probe cholestane dissolved in a narrow distribution poly(n-butyl acrylate) sample has been investigated via electron spin resonance (ESR) spectroscopy. The measurements were carried out in a wide temperature range: different dynamic regions have been recognized, and the coupling of the probe dynamics to the α and secondary relaxations has been revealed. In particular, the coupling with the structural relaxation is ruled by two fractionary Vogel-Fulcher laws (VF). The crossover from one VF region to the other occurs at the temperature T(C) = 1.17T(g), signalling the onset of the cooperativity in the dynamics and confirming a behaviour previously observed in ESR studies carried out on polymeric glass-formers. Furthermore, in this work we discuss the activated regime at the highest temperatures and show that the activation energy does not depend on the length of the polymer main- and side-chains, while its onset temperature linearly depends on the chain length.

We will consider the use of the bond model in characterizing, by the direct calculation route, the full excitation profile. The present work sets the temperature behaviour of the excessive value of some thermodynamic quantities, such as configurational entropy and heat capacity of two homologous disaccharide aqueous solutions. The findings represent important data for understanding the better lyoprotectant effectiveness of trehalose in comparison with sucrose.

Glass transition during bulk polymerization was studied in free-radical cross-linking copolymerization (FCC) of methyl methacrylate (MMA) using the steady-state fluorescence (SSF) technique. Naphthalene (N) was used as a monomer and excimer forming probe. Changes in the viscosity of the pregel solutions due to gel formation dramatically enhance both monomer and excimer fluorescent yield of N molecules. The reaction time at which the monomer and excimer intensities exhibit a sudden increase corresponds to the reaction time at which the rate of polymerization becomes maximum resulting from the gel effect. This effect was used to study the gelation of MMA, as a function of time, in various N concentrations. The results were interpreted in the view of percolation theory. The gel fraction, beta, and weight average degree of polymerization, gamma, exponents beta=0.40 +/- 0.02 and gamma=1.70 +/- 0.07 were found in agreement with percolation results for both monomer and excimer measurements, respectively. Publisher's Version Q3 WOS:000230649700003

The static structure factor and associated dynamics have been investigated in a series of block copolymers of poly(methyl vinyl ether) (PMVE) and poly(isobutyl vinyl ether) (PiBVE) using x-ray scattering and dielectric spectroscopy (DS). The origin of the dynamic arrest at the glass temperature $({T}_{g})$ of PiBVE has been explored by temperature- and pressure-dependent DS and pressure-volume-temperature measurements. Both temperature and volume are responsible for the segmental dynamics but temperature has a stronger effect. The copolymers display a minimal dynamic asymmetry $(\ensuremath{\Delta}{T}_{g}\ensuremath{\sim}7\phantom{\rule{0.3em}{0ex}}\mathrm{K})$, nevertheless, are spatially and dynamically heterogeneous. Increasing pressure, unlike temperature, enhances the dynamic heterogeneity. This effect originates from the distinctly different pressure sensitivities of the homopolymers and can be traced back to differences in local packing.