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"Organosilanes bearing alkoxysilane are widely used in sol-gel process. In this process, the hydrolysis reaction is usually carried out in aqueous or hydroalcoholic solutions and the condensation reaction requires high temperatures. The hydrolysis of the alkoxysilanes in the presence of water is fast and can be considered as complete. The obtained silanols can then condensate into oligomers by a much slower reaction that depends on temperature. Our objective is to devise a simple synthesis way for grafting such coupling agent onto the mineral fillers surface without using solvent and heating. Mineral fillers are used as reinforcement in dental composites based on Bis-GMA/TEGDMA. The way developed in this work involves a photoinitiated sol-gel process. It consists in using a photoacid generator to activate the hydrolysis and condensation reactions under atmospheric humidity. Mineral oxides usually used in dental materials were chosen as inorganic filler: the zirconia (ZrO2) which is a radiopacifiant agent and the alumina (Al2O3) which allows improving the mechanical properties of the composite. A kinetic study of the self-condensation of the 3-MPS used as coupling agent in the presence of Irgacure 250 ® as photoacid generator was carried out and the operating conditions (irradiation intensity and time) of the functionalization reaction were optimized. Grafted fillers were characterized by FTIR spectroscopy and thermogravimetic analysis. FTIR and TGA analyses of the particles after treatment allow confirming the grafting. Compared to the conventional way, the photoinitiated process proves to be faster, easier, less expensive in energy, and much more efficient in terms of 3-MPS grafted quantity. "

In this work, the design and characterization of new supported ionic liquid membranes, as medium-temperature polymer electrolyte membranes for fuel-cell application, are described. These membranes were elaborated by the impregnation of porous polyimide Matrimid® with different synthesized protic ionic liquids containing polymerizable vinyl, allyl, or methacrylate groups. The ionic liquid polymerization was optimized in terms of the nature of the used (photo)initiator, its quantity, and reaction duration. The mechanical and thermal properties, as well as the proton conductivities of the supported ionic liquid membranes were analyzed in dynamic and static modes, as a function of the chemical structure of the protic ionic liquid. The obtained membranes were found to be flexible with Young’s modulus and elongation at break values were equal to 1371 MPa and 271%, respectively. Besides, these membranes exhibited high thermal stability with initial decomposition temperatures &gt, 300 °C. In addition, the resulting supported membranes possessed good proton conductivity over a wide temperature range (from 30 to 150 °C). For example, the three-component Matrimid®/vinylimidazolium/polyvinylimidazolium trifluoromethane sulfonate membrane showed the highest proton conductivity—~5 × 10−2 mS/cm and ~0.1 mS/cm at 100 °C and 150 °C, respectively. This result makes the obtained membranes attractive for medium-temperature fuel-cell application.

A biobased photo-healable thermoset coating has been developed from 4 components in only 2 steps via a solvent-free process involving an epoxy/amine reaction. Its composition includes epoxidized linseed oil and a dynamic molecule (4,4′-diaminodiphenyl disulfide) which, under UV irradiation, can be photolyzed reversibly. Compared to an analogous material without disulfide bond, this coating exhibits a lower crosslinking density and a higher elongation at break. Importantly, a 100 μm depth scratch has been significantly repaired under UV light: a photo-healable coating having both thermoplastic and thermosetting properties has thus been elaborated.

Thick epoxy composite materials (>1 mm) have been elaborated by a room temperature process involving photopolymerization through a cationic pathway. Two epoxy resins (glycidyl ether and cycloaliphatic) were chosen as model organic matrix whereas microspherical silica particles (until 50 wt-%) were used as reinforcement. The monitoring of the photopolymerization kinetics by FTIR spectroscopy has first shown the existence of a conversion gradient in the material thickness, which resulted either from light absorption by the matrix and/or from light scattering induced by the presence of filler. More especially, the light scattering was found to be all the more important as the refractive index gap between filler and matrix was high. However, this conversion heterogeneity has then been able to be compensated by ageing involving a postpolymerization reaction at room temperature. The analysis of the mechanical properties of the obtained materials has confirmed that it was possible to obtain thick photocomposite materials homogeneously crosslinked. This homogeneity was even enhanced by using a radiation in the 300−440 nm wavelength range.

International audience; Herein, a model study of the photoinitiated thiol–ene reaction was carried out on unsaturated fatty methyl esters at room temperature and without photoinitiator. Reaction kinetics were monitored by FTIR spectroscopy and reaction products were identified by high resolution mass spectrometry coupled to ion mobility spectrometry. This set of analytical tools enabled us to highlight the concomitance of fatty double bond oxidation and thiol–ene addition when such a formulation was exposed to UV radiation. Indeed, thiol–ene adducts were identified on fatty moieties oxidized or not, without prevalence of one reaction over the other: photoinitiated thiol–ene addition could occur on preoxidized products, and photooxidation could occur on thiol–ene adducts. However, the presence of oxidized fatty products such as peroxides and zwitterionic species was proved to be favourable to the photocrosslinking of fatty coatings by thiol–ene addition.

In the quest for green and friendly processes in polymer chemistry, we report herein a new process for bio-based coatings as an attractive alternative to the common drying of oils. This process involves the photoinitiated thiol-ene chemistry under air for the preparation of linseed oil-based biocoatings. Several parameters were investigated to determine the optimal formulation composition and irradiation conditions. Native or stand linseed oil triglycerides were then crosslinked in the presence of 0.5 equivalent of various thiols (SH/ene) under 20 min UV exposure, without photoinitiator nor solvent. 10–20 μm thick coatings constituted of about 80 wt% of linseed oil were obtained. They exhibited at least equal physico-chemical properties compared to coatings dried by simple oxidation. It was found that oxidation of fatty moieties occurred during and after irradiation and has a beneficial effect on the properties of the final coatings.

Photopolymerization of composite materials is not trivial. Indeed, the main drawback of this process is the light energy attenuation within the material, resulting in limited photopolymerized thicknesses. This light attenuation with depth relates to light absorption and scattering within the reaction mixture. Furthermore, the light scattering is influenced by the gap between filler and polymer refractive indices. In order to understand the influence of these parameters on both process and homogeneity of the resulting photocomposites, we present here a numerical model that provides access to data that are not experimentally accessible as the evolution of scattering coefficient or conversion gradient inside thick composite material during and after photocuring. To exemplify the model, three different cases representative in terms of optical properties will be discussed.

International audience; Solvent-free microwave-assisted synthesis was carried out to prepare 2,3-dihydroxypropyl decanoate, by esterification of decanoic acid in the presence of two distinct glycerol derivatives, glycidol, and glycerol carbonate, respectively. The process described is based on microwaves heating source with electrical power in the range of 200–400 W, involving stoichiometric proportions of decanoic acid and glycerol derivatives, and using catalytic amounts of TBAI used as organocatalyst. Conversion and selectivity rates of esterification reactions were monitored by 1H and 13C{1H} NMR spectroscopy. The predominantly formed ester, 2,3-dihydroxypropyl decanoate was fully characterized by infrared and NMR spectroscopy, mass spectrometry, and elemental analysis. Compared with the classical heating procedures, and whatever the glycerol derivatives used, total conversions were obtained with considerably reduced reaction times. Thus, under 300 W, esterification requires only 1 min exposure from glycidol and 5 min from glycerol carbonate. The use of heating with conventional oil bath conditions needs residence times of more than 1 h (even 24 h in the case of glycerol carbonate). The microwave-assisted synthesis also notably enhances the selectivity in 2,3-dihydroxypropyl decanoate (at 300 W, 90, and 50%, respectively), reinforcing the efficiency and the interest of the method.Practical applications: The results establish that microwave heating is well suited for the solvent-free synthesis of glycerol monodecanoate from decanoic acid and two glycerol derivatives, glycidol, and glycerol carbonate. Reaction times are drastically reduced, and in both cases, marked improvements of the conversion and selectivity are recorded. The target α-monoglyceride, 2,3-dihydroxypropyl decanoate, has various potential applications such as antimicrobial properties, bacterial inhibitory activity, or denture disinfectant.Solvent-free microwave heating conditions are applied to the synthesis of 2,3-dihydroxypropyl decanoate by esterification of decanoic acid in the presence of two glycerol derivatives, glycidol, and glycerol carbonate. In both cases, conversion and selectivity gains, as well as notable reductions of reaction times are record.

Herein the synthesis of core cross-linked (CCL) mixed micelles through a UV-promoted thiol–ene addition onto lipid core unsaturations and the subsequent release of an encapsulated drug depending on the external conditions (pH/temperature) are reported. The thiol–ene addition proceeds even in the absence of a photoinitiator to reach a complete conversion in a few minutes in bulk. The cross-linking reaction is applied in aqueous media onto lipid-b-poly(acrylic acid) (lipid-b-PAA) only and then a mixture of pH-sensitive lipid-b-PAA and thermo-sensitive lipid-block-poly(2-isopropyl-2-oxazoline) copolymers. Structurally CCL micelles, preserved in any conditions, with a stimuli-sensitive corona whose swelling depends on the external pH or/and temperature, are successfully prepared. The release of vitamin K1 (VK1) is then investigated from all the previous systems and demonstrates a strong dependency to the external conditions. Indeed, the dual-sensitive CCL micelles release VK1 only when two triggers (pH 10 and T = 38 °C) are simultaneously activated.

The photoinitiated polymerization of a dental formulation is composed of Mixture of monomers 75%Bis-GMA/25%TEGDMA and CQ/DMAEMA as radical photoinitiator was studied by using isothermal photocalorimetry. The effect of temperature, light intensity and photoinitiating system concentration on reaction was investigated. A maximum conversion was obtained for a photoinitiator system concentration of 1% (w/w) and for the highest light intensity studied. It should be noted that a correlation between the glass transition temperature of the final polymer and the conversion has been studied.Keywords: dental composite; photopolymerization; dimethacrylate resin; photoinitiator system

RATIONALE Polyamides (PA) are among the most used classes of polymers because of their attractive properties. Depending on the nature and proportion of the co-monomers used for their synthesis, they can exhibit a very large range of melting temperatures (Tm). This study aims at the correlation of data from mass spectrometry (MS) with differential scanning calorimetry (DSC) and X-ray diffraction analyses to relate molecular structure to physical properties such as melting temperature, enthalpy change and crystallinity rate. METHODS Six different PA copolymers with molecular weights around 3500 g mol–1 were synthesized with varying proportions of different co-monomers (amino-acid AB/di-amine AA/di-acid BB). Their melting temperature, enthalpy change and crystallinity rate were measured by DSC and X-ray diffraction. Their structural characterization was carried out by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Because of the poor solubility of PA, a solvent-free sample preparation strategy was used with 2,5-dihydroxybenzoic acid (2,5-DHB) as the matrix and sodium iodide as the cationizing agent. RESULTS The different proportions of the repeating unit types led to the formation of PA with melting temperatures ranging from 115°C to 185°C. The structural characterization of these samples by MALDI-TOF-MS revealed a collection of different ion distributions with different sequences of repeating units (AA, BB; AB/AA, BB and AB) in different proportions according to the mixture of monomers used in the synthesis. The relative intensities of these ion distributions were related to sample complexity and structure. They were correlated to DSC and X-ray results, to explain the observed physical properties. CONCLUSIONS The structural information obtained by MALDI-TOF-MS provided a better understanding of the variation of the PA melting temperature and established a structure-properties relationship. This work will allow future PA designs to be monitored. Copyright © 2014 John Wiley & Sons, Ltd.

In dental composites, the presence of inorganic fillers in the organic matrix leads to a light-scattering phenomenon that modifies the light intensity and, consequently, the ultimate polymerization yield. In this study, we aimed to characterize the impact of light scattering on the photopolymerization profiles inside thick materials. First, the photopolymerization kinetics of dental composites containing alumina or zirconia nanofillers were studied. An optimal formulation based on 75 wt% Bis-GMA, 25 wt% triethyleneglycoldimethacrylate and 1 wt% camphorquinone/dimethylaminoethylmethacrylate (1/1) was determined. The compatibility between the organic matrix and the fillers was enhanced by grafting a silane coupling agent onto the surfaces of the nanoparticles. This grafting improved the mechanical properties of the final composites without modifying the photopolymerization kinetics. The presence of nanofillers leads to a light-scattering phenomenon that influences the photoinitiated polymerization yield inside the composite. Thus, to characterize this phenomenon, a four-flux radiative transfer theory was applied to calculate the decrease in the light intensity crossing the dental composite. The conversion profiles were then calculated and compared with experimental ones. Photopolymerization of thin layers of a 75/25 (w/w) Bis-GMA/TEGDMA mixture exposed to a 465-nm monochromatic light radiation was first investigated. The final methacrylate conversion was measured by FTIR spectroscopy for different light intensities I0. Then, the variation of the light flux intensity φ inside thick samples of the previous mixture containing mineral nanofillers (Al2O3 or ZrO2) was calculated by means of a numerical model by taking into account the light scattering induced by the fillers. The obtained results permit the determination of the conversion profiles inside the loaded material and the maximal thickness that can be photopolymerized without consequent alteration of the polymerization yield and of the mechanical properties.

Allyl terminated renewable non-isocyanate polyurethanes (NIPUs) and polyureas (NIPUreas) were synthesized using the transurethanization approach. Dimethyl dicarbamate monomers were prepared by the reaction of a diamine with an excess of dimethyl carbonate (DMC). These monomers were reacted with an excess of a diamine to afford amine terminated polyureas. The amine end-groups were converted into allyl groups by reaction with 10-undecenoic acid. NIPUs were prepared by reaction of an excess of dimethyl dicarbamate monomers with a diol, affording methyl carbamate chain-ends, which were converted into ally groups by reaction with 9-decen-1-ol. All the chemical reactions were conducted under neat conditions, in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst. The obtained materials exhibited Tg values varying from −44 to −35 °C, Tm values varying from 29 to 201 °C, and thermal stabilities above 200 °C. The optimal conditions of photo-curing of the prepared materials were determined through a kinetic study of the reaction of the allyl end-groups, in the presence of benzophenone as photoinitiator.

International audience

Light scattering by filler particles is the main cause of the decrease in light intensity inside a photocurable composite material. This scattering phenomenon depends on the matrix and filler refractive index gap. This work aims to elaborate a non scattering photocured composite by minimizing this gap. Relationships between refractive index and conversion of unloaded acrylic formulations were first studied by real time infrared spectroscopy and refractometry. Refractive index of the final polymer was especially related to its monomers composition. These results allowed matching the matrix and silica refractive indexes, i.e., determining the suitable composite formulation which led to a non scattering material.

The photoinitiated polymerization of epoxidized hydroxytelechelic cis-1,4-polyisoprene and of a dual system (epoxidized/ acrylated) telechelic cis-1,4-polyisoprene in the presence of 2,2-dimethyl-1,2-hydroxyacetophenone or/and hexafluoro-phosphate triar- ylsulfonium salt has been studied by real-time infrared spectroscopy. The synthesis of photosensitives oligoisoprenes was achieved by chemical modifications of hydroxytelechelic cis-1,4-polyisoprene obtained by controlled degradation of high molecular weight cis-1,4- polyisoprene. Then, the effect of light intensity, photoinitiator concentration, addition of reactive diluent and concentration of func- tional groups on the photopolymerization process was evaluated. Concerning the cationic process, the results showed that the kinetic profile improves when photoinitiator concentration and light intensity increase. The optimum concentration of triarylsulfonium salt used as photoinitiator was determined as 5% (w/w) and the optimum light intensity was 50 mW cm � 2 . Reactive diluent (3-ethyl-3- hydroxymethyl oxetane) addition greatly improves the ultimate conversion and the polymerization rate. Subsequently, the photopoly- merization kinetic of a dual epoxidized/acrylated system was studied. The results obtained using different photoinitiator mixtures and different intensity of irradiation showed that the crosslinking of acrylate functions at the chain-end prevents the progression of the cationic process at the oxirane groups along the chain. Thus, the mobility of the cationic reactive centers was restricted by the cross- linking at the high conversion of the acrylate double bonds. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 000: 000-000, 2012

International audience; UV laser stereolithography is a rather new shaping technique that makes it possible the fabrication of complex 3D ceramic structures with a high dimensional accuracy. The green part is built through layer by layer photopolymerization of a light sensitive suspension. Polymerization is thus a critical step to control in this shaping technique. Photopolymerization, with the initiation, propagation and termination reactions, involves the mobility of reactive species and is then sensible to the rheology of the media. This study investigated the influence of the rheology of suspensions of silica particles in an acrylate oligomer and of the intergranular curable organic phase on the UV polymerization. In this respect, the effects of the powder concentration, the state of dispersion and of the dilution of the reactive oligomer on polymerization, are measured. In addition, the influence of the powder loading on the cure depth and cure width, which are respectively pertinent indicators of the reactivity of the suspension and of the dimensional accuracy of the green part, is evaluated.

Monodispersed spherical silver nanoparticles with 35±5 nm diameter were prepared by microwave irradiation of an AgNO3 aqueous solution in poly(ethylene glycol) (PEG). Thanks to the hydroxyl groups at the chain-ends of the PEG, the matrix of the Ag nanoparticles suspension was well incorporated into a polyurethane backbone, allowing a good distribution of the metal particles inside the final nanocomposite without aggregation. An optimal antibacterial activity was observed for a 35 p.p.m. Ag concentration against P. aeruginosa and E. faecalis without significant variation of the intrinsic physicochemical properties of polyurethane material.

New photosensitive oligoisoprenes were synthesized by controlled degradation of high molecular weight cis-1,4-polyiso- prene and successive chemical modification of the chain-ends. Oligomers with diacrylate extremities were synthesized, characterized, and used in photocrosslinking reactions in different conditions. The photoinitiated polymerization of the diacrylate oligoisoprenes was carried out using 2,2-dimethyl-2-hydroxyacetophenone (Darocur 1173) as initiator and the reaction was monitored by photoca- lorimetry-DSC and real time FTIR spectroscopy. The influence of oxygen, photoinitiator concentration, light intensity, diluting agent, and oligomers molecular weight on the reaction rate was investigated. It was found that the presence of oxygen does not influence the photopolymerization kinetics of the diacrylate oligoisoprenes. Maximum conversion was obtained for a photoinitiator concentra- tion of 5% (w/w) and for a light intensity of 13.5 mW/cm 2 . Decreasing the formulation viscosity by addition of a diluent (1,6-hexa- nediol diacrylate) raised the photopolymerization rate, by increasing the reactive species mobility. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 000: 000-000, 2012

Rationale The grafting of maleic anhydride onto fatty C=C double bonds is a well-known and used method to functionalize triglyceride molecules. Nevertheless, grafted products are not actually structurally well defined. In this work, the thermal grafting of maleic anhydride onto (un)saturated fatty acid esters without the use of an initiator was characterized in order to determine the nature of the products formed during this reaction. Methods Complementary spectrometric techniques, ESI-MS(n) (ion-trap mass spectrometer), IMS-MS(n) (Q-IMS-TOFMS) and GC/MS, were used to identify the grafted products which were prepared using either ethyl oleate (EtO) or methyl linoleate (MeL) as model molecules and maleic anhydride (MA). Lithiated adducts were investigated since they yield useful structural information when subjected to collision-induced dissociation (CID) in tandem mass spectrometry. Results A high number of products are formed during MA grafting and various reaction types could occur. Radical addition of maleic anhydride followed by combination or elimination reactions led to succinic and maleic anhydride grafting, respectively. The addition occurred with or without double-bond shift; the resulting derivatives showed succinic and maleic anhydride branching in the α-position relative to the double bond or onto the carbon atom of the initial double bond. Some structures obtained by radical addition and combination were also consistent with the Alder ene functionalization reaction. The Diels-Alder addition between di-unsaturated fatty acid chains and maleic anhydride could yield cyclic forms of MA-grafted derivatives. Conclusions We have shown that ESI-MS(n) and IMS-MS(n) allow the identification of grafted products providing relevant structural information concerning isomers. These methods permit the rapid and direct analyses of 'crude reaction mixtures'.

RATIONALE: Polyamides (PA) belong to the most used classes of polymers because of their attractive chemical and mechanical properties. In order to monitor original PA design, it is essential to develop analytical methods for the characterization of these compounds that are mostly insoluble in usual solvents. METHODS: A low molecular weight polyamide (PA11), synthesized with a chain limiter, has been used as a model compound and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). In the solvent-based approach, specific solvents for PA, i.e. trifluoroacetic acid (TFA) and hexafluoroisopropanol (HFIP), were tested. Solvent-based sample preparation methods, dried-droplet and thin layer, were optimized through the choice of matrix and salt. Solvent-based (thin layer) and solvent-free methods were then compared for this low solubility polymer. Ultra-high-performance liquid chromatography/electrospray ionization (UHPLC/ESI)-TOF-MS analyses were then used to confirm elemental compositions through accurate mass measurement. RESULTS: Sodium iodide (NaI) and 2,5-dihydroxybenzoic acid (2,5-DHB) are, respectively, the best cationizing agent and matrix. The dried-droplet sample preparation method led to inhomogeneous deposits, but the thin-layer method could overcome this problem. Moreover, the solvent-free approach was the easiest and safest sample preparation method giving equivalent results to solvent-based methods. Linear as well as cyclic oligomers were observed. Although the PA molecular weights obtained by MALDI-TOF-MS were lower than those obtained by (1)H NMR and acido-basic titration, this technique allowed us to determine the presence of cyclic and linear species, not differentiated by the other techniques. TFA was shown to induce modification of linear oligomers that permitted cyclic and linear oligomers to be clearly highlighted in spectra. CONCLUSIONS: Optimal sample preparation conditions were determined for the MALDI-TOF-MS analysis of PA11, a model of polyamide analogues. The advantages of the solvent-free and solvent-based approaches were shown. Molecular weight determination using MALDI was discussed.

Several theories have been proposed concerning the stand oil reaction but no precise reaction scheme has been described. In this work, the stand reaction of linseed oil was characterized in order to determine the nature of the products formed during this reaction. Using complementary analytical techniques (more especially NMR and mass spectrometry), the existence of two different reactions was demonstrated: the Diels-Alder addition between fatty acid chains and the addition of a methylene radical on double bonds, followed by combination or elimination reactions.

A detailed characterization of triacylglycerols (TAGs) present in linseed oil samples from a local producer was performed using electrospray ionization and two mass spectrometric approaches; direct infusion multi-stage mass spectrometry (MSn) experiments and liquid chromatography/tandem mass spectrometry (LC/MS/MS) using non-aqueous reversed-phase chromatographic conditions. The combination of both approaches permitted the identification of 26 TAGs. Comparison of the two analytical approaches showed that discrimination of regioisomers was achieved from MS3 data while other isobaric species were separated and identified by LC/MS/MS analysis. The results we obtained were also compared with those previously reported. The TAG composition of the studied linseed oil is qualitatively identical to that of linseed oils from various sources in Europe, Canada, Argentina or India. However, a few differences were observed with regard to the proportions of some TAGs; these can be explained by variations in the culture conditions, climate, and variety of the seeds. Copyright © 2009 John Wiley & Sons, Ltd.

The aim of this work was to understand the reactions involved in the photocrosslinking processes of a alpha,omega-unsaturated copolyamide foreseen as a new UV-curable powder coating. The crosslinking reaction was photoinitiated with benzophenone. In this paper, the photochemical reaction between benzophenone and several model compounds was investigated. The model compounds contained functional groups which could be present in copolyamide. The products resulting from UV curing were identified using a combination of high-resolution mass spectrometry and MS(n) experiments. The characterization of the products allowed localization of the hydrogen abstraction by the type II photoinitiator during UV curing and, consequently, the determination of the reactive sites of the unsaturated polyamide chain which were involved in the photochemical reaction.

This work deals with the elaboration of a new UV-curable powder coating for heat sensitive substrates. This powder contains a α,ω-unsaturated copolyamide 6/11/12 having a melting point of 107 °C and 4% (w/w) of photoinitiator. After description of the copolyamide synthesis, the photochemical reaction was investigated in the presence of two Norrish II photoinitiators (benzophenone and 4-phenylbenzophenone). The influence of the photocrosslinking on the crystallinity of the ultimate materials was studied. It was shown that the photochemical reaction can take place even when the sample is at the solid state and that its yield increases with the temperature and the time of irradiation. Lastly, the influence of the crystallinity/crosslinking ratio was characterized by measuring the swelling of the UV-cured materials into different solvents.

International audience; An undecylenic acid-based monoglyceride prepared from glycidol and undecylenic acid is used as suitable and tunable synthon for polymerization applications. Epoxidation and acrylation reactions lead to photopolymerizable monomers while transesterification with dimethyl carbonate, metathesis and aminolysis reactions provide access to polyhydroxyurethane-based materials. The successive intermediates were synthesized according to a green chemistry approach implicating solvent-less and catalyzed reactions, and were at each step fully characterized by infrared, 1H and 13C{1H} NMR spectroscopy, elemental analysis and mass spectrometry. Analyses of the resulting polymer materials were performed by infrared, 1H and 13C{1H} NMR, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC).

Herein, we report the use of the photoinitiated thiol–epoxy chemistry for the preparation of a new biosourced self-healing coating. Epoxidized cottonseed oil is used as the main reagent (>80 wt%) and photocrosslinked in the presence of 0.25 equivalents of 7-mercapto-4-methyl coumarin, used as a photodimerizable and healable reactant. The reaction is initiated with 2 wt% of a photobase generator (PBG). The stability of the thiol–epoxy mixture under storage and the oxygen-promoted photoinitiating system are some of the advantages illustrated in this study. The physicochemical properties of the resulting coatings as well as the photoreversibility of the coumarin derivative once grafted on the vegetable oil are studied. The photoinitiation step is demonstrated to be efficient for the grafting of the healing reagent as well as for epoxy homopolymerization.

The aim of the present paper is to report the reduction of the water uptake of sunflower pith, sustainable raw by-product without current added-value in oilseed crops production. The water-sensitivity is ascribed to its structure, because mainly constituted of carbohydrates, due to the formation of additional hydrogen bondings with water molecules. Two environmentally-friendly approaches were applied to provide a modified layer presenting water resistance in surface of sunflower pith in order to keep its low-density property. The first approach based on vegetable oil corresponds to thermal and photochemical treatments. A thin layer of virgin or acrylated epoxidized soybean oil was sprayed on the pith surface, and thereafter was thermally cured or photocured, respectively. The second approach consisted in a solventless chemical modification of the pith surface by a cold plasma treatment. Both approaches were successfully performed: water resistance of sunflower pith was clearly enhanced, especially with oil-based treatments; while maintaining its integrity. Developing new and promising ecological water-resistant products of low density from sunflower pith is thought of increasing interest with potential practical applications.

International audience; Partially or fully biosourced (co)polyamides have been prepared from commercial (11-aminoundecanoic acid, octadec-9-en-1,18-dioic acid, dodecan-1,12-diamine) and/or an original branched and unsaturated ((9Z)-octadecene-1,12-diamine) monomer. Undec-11-enoic acid was used as chain limiter in order to obtain controlled average number molecular weights around 7000 g mol−1. By varying the relative composition of monomers and/or the amount of side chains and/or the amount of unsaturated repeating units, copolyamides exhibiting low glass transition temperatures ranging from −31 to 3 °C and low melting temperatures ranging from 60 to 143 °C have been obtained. The branched monomer was found to act as internal plasticizer. Coatings have been prepared from these polymer materials at their melting temperatures. The presence of carbon–carbon double bonds on the polymer backbone allowed their photocrosslinking in the presence of benzophenone. This UV curing enhanced the hardness of the obtained coatings. These polymers are therefore expected to be used as bio-based UV powder coatings for heat sensitive substrates.

The existence of entirely biobased AA–BB polyamides is very limited because of the low availability of biosourced diamines. In this work, saturated and unsaturated diamines, with dangling hexyl chain, were successfully synthesized from methyl ricinoleate. These new monomers were reacted with several diacids to prepare novel partially to totally biobased AA–BB polyamides. Linear polyamide analogues were also prepared from commercial monomers. The physico-chemical properties of the obtained polymers were assessed by DSC and TGA analysis. An auto-plasticizing effect owing to the dangling chains was evidenced. The new branched monomers and polymers are expected to be used when modification of the properties of existing polyamides are required. Practical applications: The new branched monomers and polymers are expected to be used as green and renewable plasticizers for modification of the properties of existing polyamides. Furthermore, the presence of the carbon–carbon double bonds in the main chains would be beneficial to perform polyamide chemical modifications at the molten state or to achieve cross-linking reactions suitable for coating applications. Elaboration of new branched renewable polyamides

The photoinitiated thiol–ene cross-linking of a dimethacrylate polyether of Bisphenol A and pentaerythritol tetrakis 2-mercaptopropionate was studied in the presence of 2,2-dimethyl-2-hydroxy acetophenone (Darocur 1173). Two complementary techniques were used: photocalorimetry and real-time infrared spectroscopy. In the first part, the kinetic reaction was characterized by a stoichiometric mixture in reactive functions. The influence of temperature, photoinitiator concentration and ultraviolet (UV) light intensity was investigated. The results mainly show that the methacrylate homopolymerization is faster than the thiol–ene addition so that the reaction is usually stopped because of the complete consumption of the methacrylate double bonds. A theoretical approach has allowed us to determine a transfer constant of 0.26. Moreover, an increase in the autoacceleration rate was observed in the presence of the thiol monomer. In the second part, the molar fraction of methacrylate double bonds and thiol functions was changed to determine the effect on the kinetic reaction and the glass transition temperature of the final material.

Photo-initiated polymerisation of dimethacrylate oligomers provide an easy method for producing highly crosslinked polymer networks. The physical properties of the material are dependent on the polymerisation conversion value. The determination of this conversion value is quite difficult on the final product. The first step is to measure a characteristic temperature of the glass transition. The weakness of the DSC glass transition signal makes this measure unrealisable while the DMA tan peak is broad and weak. At the difference of these two thermal analysis techniques, TSDC gives an observable signal and a Tα temperature close to the glass transition temperature region. The bad sample preparation reproducibility observed was attributed to the high conversion rate.

The effects of the presence of trapped radicals after UV irradiation were studied on a dimethacrylate oligomer. The postpolymerization reaction was characterized by differential scanning calorimetry and dynamic mechanical analysis. The photopolymerization was realized with 2,2-dimethyl-2-hydroxyacetophenone (Darocur 1173) as radical photoinitiator by using isothermal photocalorimetry. The postpolymerization was clearly shown in the isothermal mode and under N 2 atmosphere by following the variation of the glass transition temperature of the samples. The influence of crosslinking density, O 2 and thermal postcure were investigated.

In this work, we described the synthesis of silanes and polysiloxanes bearing cationic photopolymerizable groups. Two new methods were used. The first one is the reaction between 3-mercapto-propyl-1-triethoxysilane (1) and chloromethylated olefins by a phase transfer catalysis. The second one is the radical addition of (1) or poly(dimethylsiloxane-co-methylmercaptopropylsiloxane) (9) to allyl or vinyl substituted heterocyclic monomers. These methods led to the expected adducts with an excellent yield. The polysiloxanes bearing heterocyclic functional groups linked through thioether bonds were photocurable by cationic route. Under UV light intensity of 17.5 mW/cm2 , these polymers harden after 15 or 20 s.

The kinetics of photoinitiated polymerization of a dimethacrylate oligomer with 2,2-dimethyl-2-hydroxyacetophenone (Darocur 1173) was studied by using isothermal photocalorimetry. First, an autocatalytic model was used and the influence of the reaction temperature on the m and n orders of the reaction and on the phenomenological rate constant k was investigated. Then, a mechanistic model was applied to calculate the k p and k t rate constants. Their evolution with conversion was studied at 50°C.

The synthesis of new polysiloxanes bearing thioether and heterocyclic functions (epoxy or oxetane) was performed. The reaction is a radical addition between a poly(dimethyl - co-methyl mercaptopropyl) siloxane and allyl or vinyl heterocyclic compounds. The corresponding sulfones were obtained by oxidation of thioether functions by using m -chloroperbenzoic acid. All the products were characterized by 1 H NMR, SEC and viscosimetry. The cross-linking of these products with isophorone diamine was studied at different temperatures. Thermal and mechanical properties were examined by dynamical mechanical and thermogravimetric analysis.

Polyamides (PA) are among the most used classes of polymers because of their attractive properties. Depending on the nature and proportion of the co-monomers used for their synthesis, they can exhibit a very large range of melting temperatures (Tm ). This study aims at the correlation of data from mass spectrometry (MS) with differential scanning calorimetry (DSC) and X-ray diffraction analyses to relate molecular structure to physical properties such as melting temperature, enthalpy change and crystallinity rate.Six different PA copolymers with molecular weights around 3500 g mol(-1) were synthesized with varying proportions of different co-monomers (amino-acid AB/di-amine AA/di-acid BB). Their melting temperature, enthalpy change and crystallinity rate were measured by DSC and X-ray diffraction. Their structural characterization was carried out by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Because of the poor solubility of PA, a solvent-free sample preparation strategy was used with 2,5-dihydroxybenzoic acid (2,5-DHB) as the matrix and sodium iodide as the cationizing agent.The different proportions of the repeating unit types led to the formation of PA with melting temperatures ranging from 115°C to 185°C. The structural characterization of these samples by MALDI-TOF-MS revealed a collection of different ion distributions with different sequences of repeating units (AA, BB; AB/AA, BB and AB) in different proportions according to the mixture of monomers used in the synthesis. The relative intensities of these ion distributions were related to sample complexity and structure. They were correlated to DSC and X-ray results, to explain the observed physical properties.The structural information obtained by MALDI-TOF-MS provided a better understanding of the variation of the PA melting temperature and established a structure-properties relationship. This work will allow future PA designs to be monitored.

Photopolymerizable monomers based on monoglycerides were prepared by a convenient two-step procedure. The first one consists of the synthesis of highly pure monoglycerides by an organocatalyzed solvent-free route. This process was carried out by condensation of bio-sourced carboxylic acids (i.e. butyric, decanoic, undecylenic or stearic acids) with glycerol carbonate or glycidol in the presence of a quaternary ammonium salt as a catalyst. The obtained bio-based monoglycerides were modified in the second step by reaction with acryloyl and methacryloyl chloride leading to a series of new diacrylated and dimethacrylated monomers. The structures of the monoglycerides, diacrylated and dimethacrylated monomers were fully characterized by spectroscopic methods. Photopolymerization investigations monitored by infrared spectroscopy were achieved under ultraviolet radiation in the presence of a photoinitiator. The resulting cross-linked materials were analyzed by thermal gravimetric analysis, gel content determination and tests of swelling in water, ethanol and methylene chloride. Data relative to the pendulum hardness of these materials are also included.

International audience; The structural characterization of Polyamides (PA) was achieved by tandem mass spectrometry (MS/MS) with a Laser Induced Dissociation (LID) strategy. Because of interferences for precursor ions selection, two chemical modifications of the polymer end groups were proposed as derivatization strategies. The first approach, based on the addition of a trifluoroacetic acid (TFA) molecule, yields principally to complementary bn and yn product ions. This fragmentation types, analogous to those obtained with peptides or other PA, give only poor characterization of polymer end-groups.[1] A second approach, based on the addition of a basic diethylamine (DEA), permits to fix the charge and favourably direct the fragmentation. In this case, bn ions were not observed. The full characterization of ω end group structure was obtained, in addition to the expected yn and consecutive fragment ions.

Resume Les travaux presentes concernent la synthese de polysiloxanes photoreticulables porteurs de greffons epoxy norbornene. A partir du 5-vinyl-2-norbornene, deux voies de synthese ont ete utilisees. La premiere met en oeuvre une suite de trois reactions: une hydrosilylation, une condensation avec un dihydroxy α,ω-polydimethyl siloxane suivi d'une epoxydation. La seconde consiste a synthetiser le 2,3-epoxy-5-vinyl norbornene puis a le greffer par hydrosilylation sur un polydimethyl siloxane porteur de fonctions SiH. Apres caracterisation par RMN 2D (1H1H et 1H13C), IRTF, etc. nous avons etudie la photoreticulation cationique d'un de ces produits en presence de triaryl sulfonium hexafluoroantimoine. En fonction de la temperature, le taux de conversion passe par un maximum vers 50–60 °C.

Resume La synthese de silanes porteurs de groupes photopolymerisables par voie cationique aete realisee par deux methodes: la premiere est l'addition radicalaire d'un thiol silicie, le mercaptopropyl triethoxysilane (1), sur des monomeres allyliques ou vinyliques ayant diverses fonctions heterocycliques, la seconde est la catalyse par transfert de phase du compose 1 avec des olefines chloromethylees. Cetteetude montre que les thiols silicies reagissent selectivement, dans nos conditions experimentales, sur les doubles liaisons dans le cas de l'addition radicalaire et sur les fonctions CH2—Cl dans le cas de la catalyse par transfert de phase. Tous les produits obtenus sont identifies par RMN 1H et 13C. Ces nouvelles methodes d'obtention de silanes monomeres par reaction de monoaddition de thiol silicie donnent les composes attendus avec un excellent rendement.

This paper reports the synthesis of an amphiphilic copolymer from linseed oils and its successive auto-association in water into pH-sensitive micelles. An original ATRP lipoinitiator is first designed from linseed oil in two steps. tert -butyl acrylate ( t BA) polymerization is consequently initiated from this original initiator and amphiphilic copolymers are obtained after subsequent acidolysis of the P t BA block into poly(acrylic acid) (PAA). The ability of a lipid- b -PAA copolymer to auto-associate in water is finally investigated through different techniques (Fluorescence, Surface Tension, QELS). This copolymer forms well-defined micelles in acidic media with a low critical micellar concentration (cmc) of 7.6 mg L −1 and dissociates when the pH is raised above 7.

The grafting of maleic anhydride onto fatty C=C double bonds is a well-known and used method to functionalize triglyceride molecules. Nevertheless, grafted products are not actually structurally well defined. In this work, the thermal grafting of maleic anhydride onto (un)saturated fatty acid esters without the use of an initiator was characterized in order to determine the nature of the products formed during this reaction.Complementary spectrometric techniques, ESI-MS(n) (ion-trap mass spectrometer), IMS-MS(n) (Q-IMS-TOFMS) and GC/MS, were used to identify the grafted products which were prepared using either ethyl oleate (EtO) or methyl linoleate (MeL) as model molecules and maleic anhydride (MA). Lithiated adducts were investigated since they yield useful structural information when subjected to collision-induced dissociation (CID) in tandem mass spectrometry.A high number of products are formed during MA grafting and various reaction types could occur. Radical addition of maleic anhydride followed by combination or elimination reactions led to succinic and maleic anhydride grafting, respectively. The addition occurred with or without double-bond shift; the resulting derivatives showed succinic and maleic anhydride branching in the α-position relative to the double bond or onto the carbon atom of the initial double bond. Some structures obtained by radical addition and combination were also consistent with the Alder ene functionalization reaction. The Diels-Alder addition between di-unsaturated fatty acid chains and maleic anhydride could yield cyclic forms of MA-grafted derivatives.We have shown that ESI-MS(n) and IMS-MS(n) allow the identification of grafted products providing relevant structural information concerning isomers. These methods permit the rapid and direct analyses of 'crude reaction mixtures'.

International audience; A new synthesis process of polymer materials based on vegetable oil has been developed. First, linseed oil was thermally polymerized in bulk at 300 °C under an inert atmosphere. Next, the obtained stand oil was functionalized in a two-step one-shot process without solvent in order to graft on some photopolymerizable groups. The first step consisted of a bulk reaction with maleic anhydride at 220 °C under an inert atmosphere. The grafted anhydride groups were then used in the second step as an anchor for grafting 2-hydroxyethylmethacrylate at room temperature. Finally, the materials were prepared by UV-curing of the modified linseed oil and then characterized. The obtained materials are flexible, hydrophobic and not biodegradable, and may have potential applications in flexible coatings.

UV polymerizations in the presence of a photobleachable initiator are studied. The photoinitiator concentration vs time and the UV radiation intensity evolution within the sample are calculated according to rate equations. Polymerization and temperature profiles inside the sample are calculated assuming steady-state conditions. Thermal boundary conditions are chosen for orthopedic applications. The polymerization is then investigated under a range of photoinitiation conditions to access the ability to form thick materials. Theoretical results indicate that both cure depth and temperature rise can be controlled through the use of a photobleachable initiator and variation of the initiating UV radiation intensity during the polymerization.

The aim of this work was to understand the reactions involved in the photocrosslinking processes of a alpha,omega-unsaturated copolyamide foreseen as a new UV-curable powder coating. The crosslinking reaction was photoinitiated with benzophenone. In this paper, the photochemical reaction between benzophenone and several model compounds was investigated. The model compounds contained functional groups which could be present in copolyamide. The products resulting from UV curing were identified using a combination of high-resolution mass spectrometry and MS(n) experiments. The characterization of the products allowed localization of the hydrogen abstraction by the type II photoinitiator during UV curing and, consequently, the determination of the reactive sites of the unsaturated polyamide chain which were involved in the photochemical reaction.

The UV light behavior crossing a thick scattering and absorbing paint film has been modelled by a four-flux radiative transfer theory. For all that, the scattering characteristics of the coating as well as the calculation of the UV intensity decay through the coating thickness were measured versus TiO2 pigment concentration. Thanks to these results, the conversion profiles in the coating thickness were obtained by numerical modeling and the influence of TiO2 pigment concentration on these conversion profiles was discussed.