Proteins have an indispensable role in the cell. They carry out a wide variety of structural, catalytic and signaling functions in all known biological systems. To perform their biological functions, proteins establish interactions with other bioorganic molecules including other proteins. Therefore, protein-protein interactions is one of the central topics in molecular biology. My thesis is devoted to three different topics in the field of protein-protein interactions. The first one focuses on solvent contribution to protein interfaces as it is an important component of protein complexes. The second topic discloses the structural and functional potential of fluorine's unique properties, which are attractive for protein design and engineering not feasible within the scope of canonical amino acids. The last part of this thesis is a study of the impact of charged amino acid residues within the hydrophobic interface of a coiled-coil system, which is one of the well-established model systems for protein-protein interactions studies. I. The majority of proteins interact in vivo in solution, thus studies of solvent impact on protein-protein interactions could be crucial for understanding many processes in the cell. However, though solvent is known to be very important for protein-protein interactions in terms of structure, dynamics and energetics, its effects are often disregarded in computational studies because a detailed solvent description requires complex and computationally demanding approaches. As a consequence, many protein residues, which establish water-mediated interactions, are neither considered in an interface definition. In the previous work carried out in our group the protein interfaces database (SCOWLP) has been developed. This database takes into account interfacial solvent and based on this classifies all interfacial protein residues of the PDB into three classes based on their interacting properties: dry (direct interaction), dual (direct and water-mediated interactions), and wet spots (residues interacting only through one water molecule). To define an interaction SCOWLP considers a donor–acceptor distance for hydrogen bonds of 3.2 Å, for salt bridges of 4 Å, and for van der Waals contacts the sum of the van der Waals radii of the interacting atoms. In previous studies of the group, statistical analysis of a non-redundant protein structure dataset showed that 40.1% of the interfacial residues participate in water-mediated interactions, and that 14.5% of the total residues in interfaces are wet spots. Moreover, wet spots have been shown to display similar characteristics to residues contacting water molecules in cores or cavities of proteins. The goals of this part of the thesis were: 1. to characterize the impact of solvent in protein-protein interactions 2. to elucidate possible effects of solvent inclusion into the correlated mutations approach for protein contacts prediction To study solvent impact on protein interfaces a molecular dynamics (MD) approach has been used. This part of the work is elaborated in section 2.1 of this thesis. We have characterized properties of water-mediated protein interactions at residue and solvent level. For this purpose, an MD analysis of 17 representative complexes from SH3 and immunoglobulin protein families has been performed. We have shown that the interfacial residues interacting through a single water molecule (wet spots) are energetically and dynamically very similar to other interfacial residues. At the same time, water molecules mediating protein interactions have been found to be significantly less mobile than surface solvent in terms of residence time. Calculated free energies indicate that these water molecules should significantly affect formation and stability of a protein-protein complex. The results obtained in this part of the work also suggest that water molecules in protein interfaces contribute to the conservation of protein interactions by allowing more sequence variability in the interacting partners, which has important implications for the use of the correlated mutations concept in protein interactions studies. This concept is based on the assumption that interacting protein residues co-evolve, so that a mutation in one of the interacting counterparts is compensated by a mutation in the other. The study presented in section 2.2 has been carried out to prove that an explicit introduction of solvent into the correlated mutations concept indeed yields qualitative improvement of existing approaches. For this, we have used the data on interfacial solvent obtained from the SCOWLP database (the whole PDB) to construct a “wet” similarity matrix. This matrix has been used for prediction of protein contacts together with a well-established “dry” matrix. We have analyzed two datasets containing 50 domains and 10 domain pairs, and have compared the results obtained by using several combinations of both “dry” and “wet” matrices. We have found that for predictions for both intra- and interdomain contacts the introduction of a combination of a “dry” and a “wet” similarity matrix improves the predictions in comparison to the “dry” one alone. Our analysis opens up the idea that the consideration of water may have an impact on the improvement of the contact predictions obtained by correlated mutations approaches. There are two principally novel aspects in this study in the context of the used correlated mutations methodology : i) the first introduction of solvent explicitly into the correlated mutations approach; ii) the use of the definition of protein-protein interfaces, which is essentially different from many other works in the field because of taking into account physico-chemical properties of amino acids and not being exclusively based on distance cut-offs. II. The second part of the thesis is focused on properties of fluorinated amino acids in protein environments. In general, non-canonical amino acids with newly designed side-chain functionalities are powerful tools that can be used to improve structural, catalytic, kinetic and thermodynamic properties of peptides and proteins, which otherwise are not feasible within the use of canonical amino acids. In this context fluorinated amino acids have increasingly gained in importance in protein chemistry because of fluorine's unique properties: high electronegativity and a small atomic size. Despite the wide use of fluorine in drug design, properties of fluorine in protein environments have not been yet extensively studied. The aims of this part of the dissertation were: 1. to analyze the basic properties of fluorinated amino acids such as electrostatic and geometric characteristics, hydrogen bonding abilities, hydration properties and conformational preferences (section 3.1) 2. to describe the behavior of fluorinated amino acids in systems emulating protein environments (section 3.2, section 3.3) First, to characterize fluorinated amino acids side chains we have used fluorinated ethane derivatives as their simplified models and applied a quantum mechanics approach. Properties such as charge distribution, dipole moments, volumes and size of the fluoromethylated groups within the model have been characterized. Hydrogen bonding properties of these groups have been compared with the groups typically presented in natural protein environments. We have shown that hydrogen and fluorine atoms within these fluoromethylated groups are weak hydrogen bond donors and acceptors. Nevertheless they should not be disregarded for applications in protein engineering. Then, we have implemented four fluorinated L-amino acids for the AMBER force field and characterized their conformational and hydration properties at the MD level. We have found that hydrophobicity of fluorinated side chains grows with the number of fluorine atoms and could be explained in terms of high electronegativity of fluorine atoms and spacial demand of fluorinated side-chains. These data on hydration agrees with the results obtained in the experimental work performed by our collaborators. We have rationally engineered systems that allow us to study fluorine properties and extract results that could be extrapolated to proteins. For this, we have emulated protein environments by introducing fluorinated amino acids into a parallel coiled-coil and enzyme-ligand chymotrypsin systems. The results on fluorination effect on coiled-coil dimerization and substrate affinities in the chymotrypsin active site obtained by MD, molecular docking and free energy calculations are in strong agreement with experimental data obtained by our collaborators. In particular, we have shown that fluorine content and position of fluorination can considerably change the polarity and steric properties of an amino acid side chain and, thus, can influence the properties that a fluorinated amino acid reveals within a native protein environment. III. Coiled-coils typically consist of two to five right-handed α-helices that wrap around each other to form a left-handed superhelix. The interface of two α-helices is usually represented by hydrophobic residues. However, the analysis of protein databases revealed that in natural occurring proteins up to 20% of these positions are populated by polar and charged residues. The impact of these residues on stability of coiled-coil system is not clear. MD simulations together with free energy calculations have been utilized to estimate favourable interaction partners for uncommon amino acids within the hydrophobic core of coiled-coils (Chapter 4). Based on these data, the best hits among binding partners for one strand of a coiled-coil bearing a charged amino acid in a central hydrophobic core position have been selected. Computational data have been in agreement with the results obtained by our collaborators, who applied phage display technology and CD spectroscopy. This combination of theoretical and experimental approaches allowed to get a deeper insight into the stability of the coiled-coil system. To conclude, this thesis widens existing concepts of protein structural biology in three areas of its current importance. We expand on the role of solvent in protein interfaces, which contributes to the knowledge of physico-chemical properties underlying protein-protein interactions. We develop a deeper insight into the understanding of the fluorine's impact upon its introduction into protein environments, which may assist in exploiting the full potential of fluorine's unique properties for applications in the field of protein engineering and drug design. Finally we investigate the mechanisms underlying coiled-coil system folding. The results presented in the thesis are of definite importance for possible applications (e.g. introduction of solvent explicitly into the scoring function) into protein folding, docking and rational design methods. The dissertation consists of four chapters: ● Chapter 1 contains an introduction to the topic of protein-protein interactions including basic concepts and an overview of the present state of research in the field. ● Chapter 2 focuses on the studies of the role of solvent in protein interfaces. ● Chapter 3 is devoted to the work on fluorinated amino acids in protein environments. ● Chapter 4 describes the study of coiled-coils folding properties. The experimental parts presented in Chapters 3 and 4 of this thesis have been performed by our collaborators at FU Berlin. Sections 2.1, 2.2, 3.1, 3.2 and Chapter 4 have been submitted/published in peer-reviewed international journals. Their organization follows a standard research article structure: Abstract, Introduction, Methodology, Results and discussion, and Conclusions. Section 3.3, though not published yet, is also organized in the same way. The literature references are summed up together at the end of the thesis to avoid redundancy within different chapters.

Ce travail s’inscrit dans le cadre du projet Saveurs Vapeurs du Groupe SEB qui vise à développer une nouvelle gamme de cuiseurs vapeur. Cette thèse porte ainsi sur l’analyse des propriétés fonctionnelles de matériaux polymères soumis à deux types de vieillissement rencontrés lors de la cuisson à la vapeur. D’une part, la résistance à la coloration de ces derniers en présence de substances alimentaires colorantes a été évaluée, à 60°C et 100°C. Un colorimètre a été utilisé pour l’analyse de la couleur des échantillons, dans l’espace Lab. Les résultats montrent que seuls les polymères totalement fluorés résistent à la coloration après 1000 heures passées à 100°C. D’autres polymères, comme le polycarbonate, le PET et les polymères partiellement fluorés, ne présentent pas de coloration après 1000 heures à 60°C. La théorie de la solubilité a été utilisée pour la prévision des résultats, et semble fiable dans de nombreux cas. Son application nécessite cependant un approfondissement, car d’autres molécules présentes dans les substances peuvent interférer avec la sorption des molécules colorantes. D’autre part, la résistance de ces polymères au vieillissement hydrothermique a été étudiée, à des températures de 100°C, 120°C et 140°C. Les températures caractéristiques (par DSC, TGA et DMA) et les propriétés mécaniques par DMA ont été mesurées. La reprise d’eau des polymères a également été évaluée. La plupart des polymères, excepté le PE, le PET et les polyamides, ne présentent pas de modifications de leurs propriétés après un vieillissement de 1000 heures à 100°C. Après un vieillissement de 1000 heures à 140°C, seuls les polymères totalement fluorés, le polysulfone et l’ETFE ne montrent aucun signe de changement de propriétés. Ces premiers résultats nécessitent cependant une analyse plus poussée. Une étude des molécules éventuellement libérées durant le vieillissement permettrait de vérifier l’innocuité de ces matériaux / This work is incorporated within the framework of the project Saveurs Vapeurs (Steam Flavors) from the SEB Group, aimed at developing a new assortment of steam cooking devices. This PhD thus deals with the analysis of the functional properties of polymer materials subjected to two types of ageing found during steam cooking. First, coloration resistance of the latter in presence of coloring alimentary substances was evaluated, at 60°C and 100°C. A chromameter was used for the analysis of samples color, in the Lab color space. Results show that only fully fluorinated polymers resist to coloration after 1000 hours spent at 100°C. Some other polymers, like polycarbonate, PET and partially fluorinated polymers, do not show any coloration after 1000 hours at 60°C. The solubility theory was used for anticipation of the results, and seems to be reliable in many cases. However its use needs an in-depth study, because some other molecules found in the substances can interfere with the sorption of colored molecules. Second, hydrothermal ageing resistance of these polymers was studied, at temperatures of 100°C, 120°C, and 140°C. Parameters measured were the characteristic temperatures (by DSC, TGA and DMA) and mechanical properties by DMA. Water mass uptake was also evaluated. Most of the polymers, excepted PE, PET and polyamids, do not show any modification of their properties after 1000 hours ageing at 100°C. After ageing 1000 hours at 140°C, only fully fluorinated polymers, polysulfone and ETFE do not show any sign of properties change. These first results need however a further analysis. A study of possibly liberated molecules during ageing could allow to verify the inoffensiveness of these materials

Proteins have an indispensable role in the cell. They carry out a wide variety of structural, catalytic and signaling functions in all known biological systems. To perform their biological functions, proteins establish interactions with other bioorganic molecules including other proteins. Therefore, protein-protein interactions is one of the central topics in molecular biology. My thesis is devoted to three different topics in the field of protein-protein interactions. The first one focuses on solvent contribution to protein interfaces as it is an important component of protein complexes. The second topic discloses the structural and functional potential of fluorine's unique properties, which are attractive for protein design and engineering not feasible within the scope of canonical amino acids. The last part of this thesis is a study of the impact of charged amino acid residues within the hydrophobic interface of a coiled-coil system, which is one of the well-established model systems for protein-protein interactions studies. I. The majority of proteins interact in vivo in solution, thus studies of solvent impact on protein-protein interactions could be crucial for understanding many processes in the cell. However, though solvent is known to be very important for protein-protein interactions in terms of structure, dynamics and energetics, its effects are often disregarded in computational studies because a detailed solvent description requires complex and computationally demanding approaches. As a consequence, many protein residues, which establish water-mediated interactions, are neither considered in an interface definition. In the previous work carried out in our group the protein interfaces database (SCOWLP) has been developed. This database takes into account interfacial solvent and based on this classifies all interfacial protein residues of the PDB into three classes based on their interacting properties: dry (direct interaction), dual (direct and water-mediated interactions), and wet spots (residues interacting only through one water molecule). To define an interaction SCOWLP considers a donor–acceptor distance for hydrogen bonds of 3.2 Å, for salt bridges of 4 Å, and for van der Waals contacts the sum of the van der Waals radii of the interacting atoms. In previous studies of the group, statistical analysis of a non-redundant protein structure dataset showed that 40.1% of the interfacial residues participate in water-mediated interactions, and that 14.5% of the total residues in interfaces are wet spots. Moreover, wet spots have been shown to display similar characteristics to residues contacting water molecules in cores or cavities of proteins. The goals of this part of the thesis were: 1. to characterize the impact of solvent in protein-protein interactions 2. to elucidate possible effects of solvent inclusion into the correlated mutations approach for protein contacts prediction To study solvent impact on protein interfaces a molecular dynamics (MD) approach has been used. This part of the work is elaborated in section 2.1 of this thesis. We have characterized properties of water-mediated protein interactions at residue and solvent level. For this purpose, an MD analysis of 17 representative complexes from SH3 and immunoglobulin protein families has been performed. We have shown that the interfacial residues interacting through a single water molecule (wet spots) are energetically and dynamically very similar to other interfacial residues. At the same time, water molecules mediating protein interactions have been found to be significantly less mobile than surface solvent in terms of residence time. Calculated free energies indicate that these water molecules should significantly affect formation and stability of a protein-protein complex. The results obtained in this part of the work also suggest that water molecules in protein interfaces contribute to the conservation of protein interactions by allowing more sequence variability in the interacting partners, which has important implications for the use of the correlated mutations concept in protein interactions studies. This concept is based on the assumption that interacting protein residues co-evolve, so that a mutation in one of the interacting counterparts is compensated by a mutation in the other. The study presented in section 2.2 has been carried out to prove that an explicit introduction of solvent into the correlated mutations concept indeed yields qualitative improvement of existing approaches. For this, we have used the data on interfacial solvent obtained from the SCOWLP database (the whole PDB) to construct a “wet” similarity matrix. This matrix has been used for prediction of protein contacts together with a well-established “dry” matrix. We have analyzed two datasets containing 50 domains and 10 domain pairs, and have compared the results obtained by using several combinations of both “dry” and “wet” matrices. We have found that for predictions for both intra- and interdomain contacts the introduction of a combination of a “dry” and a “wet” similarity matrix improves the predictions in comparison to the “dry” one alone. Our analysis opens up the idea that the consideration of water may have an impact on the improvement of the contact predictions obtained by correlated mutations approaches. There are two principally novel aspects in this study in the context of the used correlated mutations methodology : i) the first introduction of solvent explicitly into the correlated mutations approach; ii) the use of the definition of protein-protein interfaces, which is essentially different from many other works in the field because of taking into account physico-chemical properties of amino acids and not being exclusively based on distance cut-offs. II. The second part of the thesis is focused on properties of fluorinated amino acids in protein environments. In general, non-canonical amino acids with newly designed side-chain functionalities are powerful tools that can be used to improve structural, catalytic, kinetic and thermodynamic properties of peptides and proteins, which otherwise are not feasible within the use of canonical amino acids. In this context fluorinated amino acids have increasingly gained in importance in protein chemistry because of fluorine's unique properties: high electronegativity and a small atomic size. Despite the wide use of fluorine in drug design, properties of fluorine in protein environments have not been yet extensively studied. The aims of this part of the dissertation were: 1. to analyze the basic properties of fluorinated amino acids such as electrostatic and geometric characteristics, hydrogen bonding abilities, hydration properties and conformational preferences (section 3.1) 2. to describe the behavior of fluorinated amino acids in systems emulating protein environments (section 3.2, section 3.3) First, to characterize fluorinated amino acids side chains we have used fluorinated ethane derivatives as their simplified models and applied a quantum mechanics approach. Properties such as charge distribution, dipole moments, volumes and size of the fluoromethylated groups within the model have been characterized. Hydrogen bonding properties of these groups have been compared with the groups typically presented in natural protein environments. We have shown that hydrogen and fluorine atoms within these fluoromethylated groups are weak hydrogen bond donors and acceptors. Nevertheless they should not be disregarded for applications in protein engineering. Then, we have implemented four fluorinated L-amino acids for the AMBER force field and characterized their conformational and hydration properties at the MD level. We have found that hydrophobicity of fluorinated side chains grows with the number of fluorine atoms and could be explained in terms of high electronegativity of fluorine atoms and spacial demand of fluorinated side-chains. These data on hydration agrees with the results obtained in the experimental work performed by our collaborators. We have rationally engineered systems that allow us to study fluorine properties and extract results that could be extrapolated to proteins. For this, we have emulated protein environments by introducing fluorinated amino acids into a parallel coiled-coil and enzyme-ligand chymotrypsin systems. The results on fluorination effect on coiled-coil dimerization and substrate affinities in the chymotrypsin active site obtained by MD, molecular docking and free energy calculations are in strong agreement with experimental data obtained by our collaborators. In particular, we have shown that fluorine content and position of fluorination can considerably change the polarity and steric properties of an amino acid side chain and, thus, can influence the properties that a fluorinated amino acid reveals within a native protein environment. III. Coiled-coils typically consist of two to five right-handed α-helices that wrap around each other to form a left-handed superhelix. The interface of two α-helices is usually represented by hydrophobic residues. However, the analysis of protein databases revealed that in natural occurring proteins up to 20% of these positions are populated by polar and charged residues. The impact of these residues on stability of coiled-coil system is not clear. MD simulations together with free energy calculations have been utilized to estimate favourable interaction partners for uncommon amino acids within the hydrophobic core of coiled-coils (Chapter 4). Based on these data, the best hits among binding partners for one strand of a coiled-coil bearing a charged amino acid in a central hydrophobic core position have been selected. Computational data have been in agreement with the results obtained by our collaborators, who applied phage display technology and CD spectroscopy. This combination of theoretical and experimental approaches allowed to get a deeper insight into the stability of the coiled-coil system. To conclude, this thesis widens existing concepts of protein structural biology in three areas of its current importance. We expand on the role of solvent in protein interfaces, which contributes to the knowledge of physico-chemical properties underlying protein-protein interactions. We develop a deeper insight into the understanding of the fluorine's impact upon its introduction into protein environments, which may assist in exploiting the full potential of fluorine's unique properties for applications in the field of protein engineering and drug design. Finally we investigate the mechanisms underlying coiled-coil system folding. The results presented in the thesis are of definite importance for possible applications (e.g. introduction of solvent explicitly into the scoring function) into protein folding, docking and rational design methods. The dissertation consists of four chapters: ● Chapter 1 contains an introduction to the topic of protein-protein interactions including basic concepts and an overview of the present state of research in the field. ● Chapter 2 focuses on the studies of the role of solvent in protein interfaces. ● Chapter 3 is devoted to the work on fluorinated amino acids in protein environments. ● Chapter 4 describes the study of coiled-coils folding properties. The experimental parts presented in Chapters 3 and 4 of this thesis have been performed by our collaborators at FU Berlin. Sections 2.1, 2.2, 3.1, 3.2 and Chapter 4 have been submitted/published in peer-reviewed international journals. Their organization follows a standard research article structure: Abstract, Introduction, Methodology, Results and discussion, and Conclusions. Section 3.3, though not published yet, is also organized in the same way. The literature references are summed up together at the end of the thesis to avoid redundancy within different chapters.

Le domaine du refroidissement est en constante expansion, le système actuel est basé sur la compression/décompression des fluides. Face aux problèmes environnementaux et économiques que ce système présente (natures des fluides frigorigènes et leurs recyclages, nuisances sonores et vibratoires, réglementations contraignantes), de nouvelles solutions techniques alternatives émergent. Ainsi ce travail de thèse porte sur de nouveaux systèmes de refroidissement basés sur les effets électrocalorique et magnétocalorique, respectivement présents dans des films minces de polymère fluoré et dans des composites à matrice polymère et à charges magnétocaloriques. A travers des caractérisations physico-chimiques, électriques, électrocaloriques et magnétocaloriques ces travaux se proposent d’identifier l’origine de l’effet électrocalorique dans des films minces de terpolymère P(VDF-TrFE-CTFE) ferroélectrique relaxeur, mais également d’étudier l’influence de la dispersion des particules magnétocaloriques La(Fe,Si)H dans une matrice polymère de poly(propylène) sur le phénomène magnétocalorique. De plus, dans le cadre de cette thèse, un appareil de mesure directe de l’effet électrocalorique a été développé avec le Dr. Basso de l’INRIM de Turin. La comparaison avec la méthode de mesure indirecte permet d’aborder ce phénomène d’un point de vue thermodynamique afin de faire le point sur la validité des hypothèses thermodynamiques utilisées dans le cas d’un polymère ferroélectrique relaxeur. / The cooling sector is in constant expansion, the current system is based on the compression/decompression of fluids. In front of environmental and economic problems of this system (nature of frigorigen fluids and their recycling, noise and vibration issues, restrictive regulations), new alternative technological solutions emerge. Thus this thesis provides new cooling systems based on the magnetocaloric and electrocaloric effects respectively present in thin films of fluoropolymer and composites with polymer matrix and magnetocaloric loads. Through physicochemical, electrical, electrocaloric and magnetocaloric characterizations, this work intends to identify the origin of electrocaloric effect in thin terpolymer films P(VDF-TrFE-CTFE) which is a ferroelectric relaxor, but also to study the influence of the magnetocaloric particles La(Fe,Si)H dispersion in a polymer matrix of poly(propylene) on the magnetocaloric phenomenon. In addition, as part of this thesis, a direct measurement device of the electrocaloric effect was developed with Dr. Basso from the INRIM of Turin. The comparison with the indirect measurement method comes up with this phenomenon from a thermodynamic point of view to take stock of the validity of thermodynamic assumptions used in the case of a ferroelectric polymer relaxor.

Lors de la polymérisation en suspension du chlorure de vinyle, il se forme sur les parois un dépôt de polychlorure de vinyle (PVC). Ce phénomène, nommé encroûtement, génère des problèmes car il limite la production de PVC et affecte la qualité du produit final. Dans ce contexte, un projet FUI (Fond Unique Interministériel) intitulé «Ecoating», a été financé dans le cadre d’une collaboration entre plusieurs partenaires industriels et universitaires (INEOS ChlorVinyls, Mäder Research, Avenir Group, LPIM, ESPCI-ParisTech). Deux thèses ont vu le jour au LPIM, avec pour but de développer un revêtement (photo)polymère aux propriétés anti-encroûtement durables qui permettrait d’améliorer la qualité du PVC produit, d’augmenter les quantités produites et ainsi d’améliorer la compétitivité des usines de PVC. Cette thèse s’inscrit dans le développement d’un vernis photopolymère répondant au cahier des charges. Pour éviter l’encroûtement des réacteurs, il est nécessaire de stopper une étape du mécanisme d’encroûtement comme l'adsorption sur les parois du réacteur d’un copolymère nommé Acvagen Graft Copolymer (AGC). Ce copolymère est très actif dans le phénomène d’encroûtement (site de nucléation) et se trouve principalement dans la phase aqueuse du milieu réactionnel. La stratégie de recherche élaborée dans ce projet a été basée sur le développement d'un revêtement photopolymère présentant une faible affinité pour l'eau et devant adhérer à la surface des réacteurs pour éviter la formation de croûte. Les polymères à base de fluoroacrylates ont été les premiers candidats choisis dans cette étude du fait que leurs propriétés exceptionnelles (faible énergie de surface, stabilité chimique et haute hydrophobicité...) pouvaient éviter l'adsorption de l'AGC sur les parois du réacteur, et par conséquent le développement de la croûte. Une recherche bibliographique a été réalisée pour comprendre le comportement particulier de ces molécules qui migrent vers la surface du film et s’organisent en surface pour donner des surfaces hydrophobes. Des mélanges de résines fluoroacryliques modèles ont été testés pour évaluer le caractère hydrophobe du revêtement, comprendre la migration des molécules de fluor vers l’interface en fonction de la nature de substrat et aussi déterminer l’influence de l’ajout d’additifs fluorés au mélange sur les propriétés globales du film. Cette étude nous a permis de comprendre l’influence de l’additif fluoré sur les propriétés chimiques et physiques du film. À l’échelle du laboratoire des tests d’immersion de ces revêtements déposés sur l’acier inoxydable ont étés réalisés dans l’eau chaude (80°C) afin de caractériser leur caractère hydrophobe en fonction du vieillissement dans l’eau chaude ainsi que l’adhésion du film au substrat. Nous avons observé une diminution de l'hydrophobicité de la surface du film au cours du temps lors d’une immersion. [...] / Our scientific approach has explored different strategies to develop a durable UV-cured coating with antifouling properties to prevent the crust formation. Firstly, the potential of fluoroacrylate photocurable coatings was exhaustively investigated. Indeed, their outstanding properties (low surface energy, chemical stability and high hydrophobicity...) could limit the adsorption of the AGC on the reactor walls and further encrusting. A bibliographic research highlighted the behavior of fluorinated monomers on film surface and the parameters affecting the hydrophobic properties. Different fluorinated monomers were selected. At low concentration, they provide hydrophobic surfaces on 316L stainless steel, the reference substrate. However, a decrease of the films surface hydrophobicity in hot water was observed with time, and was attributed to a disorganization of the fluorinated chains on the coating surface. An optimization of the amount of fluoroacrylate monomer was performed by confocal Raman microscopy (CRM) to promote the fluorinated chains stability on the surface before and after immersion in hot water at 80°C. The beneficial effect was found maximal at a concentration ranging from 1 to 1.8 wt%. However, even after this optimization, a decrease of the film surface hydrophobicity was observed for increased immersion time in hot water. Therefore, optimized fluoroacrylate monomer concentration was combined with alternated thermal/immersion post-treatment and has conducted to more stable photocured films. This result was attributed to a rigidification of the fluorinated chains on the film surface limiting thus, the extent of their disorganization. After this study realized at a laboratory scale, we tested the photocured coating in the VCM pilot reactor. A surface cleaning, an increase of the stainless steel roughness by shot blasting and the use of alkoxysilanes as coupling agents were implemented in order to enhance the adhesion properties of the photopolymer film on stainless steel. In addition, the use of a fluorinated monomer containing a heteroatom improved the rigidification when associated with the alternated thermal/immersion post-treatment. The crust formation was limited during four successive polymerizations in the VCM pilot reactor. A durable anti-fouling UV-coating could be not obtained due to some swelling phenomena resulting from the lack of coating adhesion or some abrasion occurring from small PVC pellets during the PVC polymerization.A second part of this project was dedicated to superhydrophobic coatings. Indeed, reducing interaction with water should lead to a better protection of the substrate. A literature review on the superhydrophobic surfaces has shown that the contact with hot water generally strongly affects their antiwetting properties and induces a large contact angle decrease. [...]