The aim of this research work was to improve the compatibility of polymer blends made from poly(lactic acid) and natural rubber (PLA/NR blends) by using modified natural rubber as a compatibilizer. Natural rubber was chemically modified into two categories: natural rubber grafted poly(vinyl acetate) copolymer (NR-g-PVAc) and block copolymers (PLA-NR diblock copolymer and PLA-NR-PLA triblock copolymer). PLA/NR blends were prepared by melting blending in a twin screw extruder and compression molded to obtain a 2-mm thick sheet. The blends contained 10-20 wt% of NR and modified NR, and the impact strength and tensile properties were investigated. The compatibilization effect was determined by DMTA, DSC and SEM. NR-g-PVAc was synthesized by emulsion polymerization to obtain different PVAc graft contents (1%, 5% and 12%). Characterization by DMTA showed an enhancement in miscibility of the PLA/NR-g-PVAc blends. NR-g-PVAc could be used as a toughening agent of PLA and as a compatibilizer of the PLA/NR blend. The block copolymers were synthesized following two routes: (1) hydroxyl telechelic natural rubber (HTNR) and lactide and (2) HTNR and PLA prepolymer. In the former route, lactide was in situ polymerized via a ring opening polymerization to be a PLA block segment during block copolymerization. In the latter route PLA prepolymer was synthesized by a condensation polymerization of L-lactic acid prior to block copolymerization. Both block copolymers acted as good compatibilizers for the PLA/NR blend by increasing the impact strength and decreasing the NR particle size. Triblock copolymers provided higher impact strength than diblock copolymers, and they were a less effective compatibilizer than NR-g-PVAc. In contrast to NR and NR-g-PVAc, the block copolymer was not a good toughening agent for PLA.

L’objectif de ce travail de thèse était l’amélioration de la compatibilité de mélanges d’acide polylactique et de caoutchouc naturel (mélanges PLA/NR) par l’ajout de dérivés du caoutchouc naturel comme agents compatibilisants. Le caoutchouc naturel a été modifié selon deux approches : synthèse d’un copolymère greffé caoutchouc- poly(vinyl acétate) (NR-g-PVAc) et synthèse de polymères à blocks PLA-NR et PLA-NR-PLA. Les mélanges PLA/NR ont été préparés par extrusion dans une extrudeuse à double vis et moulées par compression pour obtenir des feuilles de 2 mm d’épaisseur. Les mélanges contenaient 10-20% en poids de NR et NR modifiée. La résistance au choc et les propriétés en traction ont été étudiées. L’effet de compatibilisation a été déterminé par DMTA, DSC et MEB. NR-g-PVAc a été synthétisé par polymérisation en émulsion pour obtenir de copolymères avec différents contenus en PVAc greffé (1%, 5% and 12%). La caractérisation des matériaux par DMTA a montré une augmentation de la miscibilité des mélanges PLA/NR-g-PVAc.NR-g-PVAc a résulté être un agent durcissant pour le PLA et un agent compatibilisant pour les mélanges PLA/NR. Les polymères à bloc ont été synthétisés selon deux routes : (1) NR hydroxy téléquelique (HTNR) et lactide et (2) NR hydroxy téléquelique et pré-polymère PLA. Dans la première approche, le lactide a été polymérisé in situ à travers la polymérisation par ouverture de cycle pour donner un bloc. Dans la deuxième approche, le pré-polymère PLA a été synthétisé par polymérisation directe de l’acide L-lactique avant copolymérisation à blocs. Les deux types de copolymères se sont révélés de bons agents compatibilisants pour les mélanges PLA/NR, car ils ont augmenté la résistance au choc et ils ont diminué la taille des particules de caoutchouc. / The aim of this research work was to improve the compatibility of polymer blends made from poly(lactic acid) and natural rubber (PLA/NR blends) by using modified natural rubber as a compatibilizer. Natural rubber was chemically modified into two categories: natural rubber grafted poly(vinyl acetate) copolymer (NR-g-PVAc) and block copolymers (PLA-NR diblock copolymer and PLA-NR-PLA triblock copolymer). PLA/NR blends were prepared by melting blending in a twin screw extruder and compression molded to obtain a 2-mm thick sheet. The blends contained 10-20 wt% of NR and modified NR, and the impact strength and tensile properties were investigated. The compatibilization effect was determined by DMTA, DSC and SEM. NR-g-PVAc was synthesized by emulsion polymerization to obtain different PVAc graft contents (1%, 5% and 12%). Characterization by DMTA showed an enhancement in miscibility of the PLA/NR-g-PVAc blends. NR-g-PVAc could be used as a toughening agent of PLA and as a compatibilizer of the PLA/NR blend. The block copolymers were synthesized following two routes: (1) hydroxyl telechelic natural rubber (HTNR) and lactide and (2) HTNR and PLA prepolymer. In the former route, lactide was in situ polymerized via a ring opening polymerization to be a PLA block segment during block copolymerization. In the latter route PLA prepolymer was synthesized by a condensation polymerization of L-lactic acid prior to block copolymerization. Both block copolymers acted as good compatibilizers for the PLA/NR blend by increasing the impact strength and decreasing the NR particle size. Triblock copolymers provided higher impact strength than diblock copolymers, and they were a less effective compatibilizer than NR-g-PVAc. In contrast to NR and NR-g-PVAc, the block copolymer was not a good toughening agent for PLA.

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Natural compounds have been the primary resource used to produce polymeric materials by humankind since the mid-1900s. Yet, progress in bio-based polymers from renewable feedstock has encountered some obstacles, mainly due to the low prices of petroleum-based monomers, compared to natural and sustainable materials. However, most commodity plastics are non-degradable materials, and solid plastic waste accumulation adversely affects the environment. As the world population is growing and demanding chemicals, energy, and plastics materials, polymer research is focusing on synthesizing bio-based and degradable polymers. Thus, biomass, a sustainable and inexpensive feedstock, is highly appropriate for designing alternative thermoplastics that are degradable to reduce the current environmental issues. In this dissertation, three different approaches were used to afford alternative thermoplastics to petroleum‐based commodities: bio-based poly(ether-amide)s, random aromatic copolyesters, and copoly(acetal triazole)s. In our first approach, two new lignin‐derived poly(ether‐amide)s (PEA)s were prepared. Their thermal properties showed high degradation temperature (Td) ranging from 330 °C to 380 °C, and glass transition temperature (Tg) between 100 °C and 120 °C. The chemical degradation studies revealed that the PEAs were degradable in 4 M H2SO4, HNO3, and TFA in 3 days. The second polymer group synthesized were semicrystalline bio-based aromatic copolyesters with tunable thermal properties. The thermal analysis of these copolyesters revealed high Td (413 °C to 446 °C) and Tg and Tm ranging from –36 °C to 67 °C and 60 °C to 267 °C, respectively. Their crystallization behavior showed a dependence on the comonomer composition, exhibiting a pseudo-eutectic region. Finally, furfural- and benzaldehyde-based copoly(acetal triazole)s (Td range 280–340 °C) were prepared by click polymerization at room temperature. Preliminary results showed that furfural-based copoly(acetal triazole)s were susceptible to hydrolytic degradation under neutral conditions after only 8 days at 40 °C. Overall, degradable and bio-based polymers were successfully synthesized as a potential thermoplastic alternative for packaging applications.

Cette thèse propose de valoriser l’isosorbide (IS) dans le domaine des matériaux polymères biosourcés en proposant des voies originales. Après la présentation de cette molécule, nous avons détaillé les différentes voies de synthèse et d'application des composés organiques et des polymères déjà développés par la communauté scientifique. Ces derniers sont obtenus au travers de multiples étapes de fonctionnalisation ou de synthèse longues au travers de procédés peu économes en énergie ou en atomes ou même toxiques. Nous avons alors expliqué notre première stratégie visant à développer des polyacétals à base d'isosorbide (PAIS) jusqu'alors inédit. Un schéma de polymérisation reposant sur la réaction de l’isosorbide avec un halogénure de méthylène dans un solvant non toxique (DMSO) a été retenu. L’influence de différents paramètres expérimentaux (mode d'agitation, durée de réaction et stœchiométrie) a été analysée avec soin. Les meilleurs résultats ont été observés avec l’agitation mécanique à très haute vitesse (milieu réactionnel plus homogène et rendement quantitatif). Les concentrations les plus élevées d'isosorbide ont permis de produire exclusivement des polyacétals linéaires (L-PAIS) alors qu'une faible concentration et l’agitation magnétique ont également induit la formation d'oligomères cycliques. D'autres macrocycles (C-PAIS) de haute masse molaire ont pu être produits. Ces différentes classes de PAIS ont été caractérisés par de nombreuses techniques (RMN, MALDI-TOF IRTF, CES). Leurs performances physicochimiques ont également été étudiées (ATG, DSC, rhéologie..). L'allongement des chaines de L-PAIS étant concurrencé par la cyclisation, nous avons exploré l'intérêt du lactide (lévogyre et racémique) comme extenseur de chaine tout d'abord en réaction avec l'IS puis avec le L-PAIS. La catalyse organométallique a été plus efficace que la voie enzymatique (lipase PS). Les analyses chimiques et physiques menées sur les quatre grades de polymères à base d'IS et de lactide ont souligné la plus value offerte par la présence de la molécule d’isosorbide Des relations "structure-propriétés" précises et fiables incluant l'étude de la durabilité ont été menées avec soin. Enfin la même approche a pu être étendue à la production de copolymères linéaires de type PLLA-b-PAIS-b-PLLA et de PRLA-b-PAIS-b-PRLA. / This research work aims to valorise isosorbide (IS) for biobased polymeric materials using original methods. After a short introduction of this molecule, we presented the different synthesis pathways and application fields of chemical and polymers already developed in scientific community. These compounds are classically obtained through many functionalization/synthesis steps with processes far away from green chemistry. Our first strategy based on the development of polyacetals derived from isosorbide (PAIS) was explained. A reaction scheme involving isosorbide with methylene halogenate in a non-toxic solvent (DMSO) was retained. The influence of different experimental parameters (stirring mode, reaction period and stoichiometry) was carefully analysed. Best results were achieved with high-speed mechanical stirring (more homogenous reactive solution, quantitative yield). The highest isosorbide concentrations led to the exclusive production of linear polyacetals (L-PAIS) whereas a low concentration under magnetic stirring conditions induced the formation of cyclic oligomers. Other macro-cycles (C-PAIS) with high molar weight were also produced. These different kinds of PAIS were characterised by various techniques (NMR, MALDI-TOF FTIR, SEC). Their physicochemical performances were also studied (TGA, DSC, rheology…) The length increase of polymer L-PAIS chains being challenged by cyclisation, we also explored lactide use (L- and racemic) as chain extender first by the reaction with IS then with L-PAIS. The La organometallic catalysis was more efficient than enzymatic pathway (PS lipase). Both chemical and physical analyses carried out with four polymeric grades derived from IS et lactide showed the added value of isosorbide molecule. Precise and reliable "structure-properties" relations including durability study were also led. Finally, similar approach could be applied for producing linear copolymers (PLLA-b-PAIS-b-PLLA and PRLA-b-PAIS-b-PRLA)

In this paper, biochemicals with the potential to substitute fossil reference chemicals in Germany were identified using technological readiness and substitution potential criteria. Their greenhouse gas (GHG) emissions were quantified by using life cycle assessments (LCA) and their economic viabilities were determined by comparing their minimum selling prices with fossil references’ market prices. A bottom up mathematical optimization model, BioENergy OPTimization (BENOPT) was used to investigate the GHG abatement potential and the corresponding abatement costs for the biochemicals up to 2050. BENOPT determines the optimal biomass allocation pathways based on maximizing GHG abatement under resource, capacity, and demand constraints. The identified biochemicals were bioethylene, succinic acid, polylactic acid (PLA), and polyhydroxyalkanoates (PHA). Results show that only succinic acid is economically competitive. Bioethylene which is the least performing in terms of economics breaks even at a carbon price of 420 euros per ton carbon dioxide equivalent (€/tCO2eq). With full tax waivers, a carbon price of 134 €/tCO2eq is necessary. This would result in positive margins for PHA and PLA of 12% and 16%, respectively. From the available agricultural land, modeling results show high sensitivity to assumptions of carbon dioxide (CO2) sequestration in biochemicals and integrated biochemicals production. GHG abatement for scenarios where these assumptions were disregarded and where they were collectively taken into account increased by 370% resulting in a 75% reduction in the corresponding GHG abatement costs.

Cette thèse présente l’élaboration de thermodurcissables et de composites biosourcés synthétisés à partir d’huiles végétales époxydées (lin et soja) et d’alcool furfurylique (FA). La première partie de ce travail concerne l’étude de la polymérisation du FA en polyalcool furfurylique (PFA) (i) en solvants protiques polaires, (ii) en combinaison avec le bois et (iii) suivant l’ajout de nouveaux amorceurs. En solvant, les changements de structures observés ont été reliés aux propriétés thermomécaniques. Une autre modification de structure du PFA a été obtenue grâce au 2,5 diméthylfurane. Ce travail a permis d’obtenir une meilleure compréhension de la réactivité du FA au sein du bois et montre que les composites bois/PFA ont une densité et une résistance plus élevées que leurs homologues non modifiés. Enfin, l’amorçage des réactions du FA par l’acide lévulinique ou par le p-toluène sulfonylhydrazine permet de proposer deux nouveaux amorceurs, respectivement biosourcé et « latent ». La seconde partie de ce travail concerne l’élaboration d’une résine époxyde totalement biosourcée et synthétisée à partir d’huiles végétales époxydées. L’huile de lin et de soja ont été chacune copolymérisées avec un acide dicarboxylique. Un premier travail fondamental a consisté à corréler la réactivité de copolymérisation avec les structures des polymères obtenus puis à établir le lien avec les propriétés thermomécaniques. Ensuite, des nanocomposites ont été synthétisés à partir de ces résines époxydes et de sépiolite. Les différentes voies de dispersion et de modification de la sépiolite mises en œuvre conduisent à des niveaux de dispersion différents de la nanocharge au sein de la matrice. / The work presents the elaboration of biobased thermosets and composites synthesized from epoxidized vegetable oils (linseed and soybean) and furfuryl alcohol (FA). A first area of research focused on the study of the polymerisation of FA into polyfurfuryl alcohol (PFA) (i) in protic polar solvents, (ii) in combination with wood and (iii) in the presence of new reaction initiators. In presence of solvents, the observed structural changes have been linked to the thermomechanical properties. Another PFA structure modification was obtained with 2,5 dimethylfuran. This work allowed a better understanding of the reactivity of FA within the wood and shows that the obtained wood/PFA composites have higher density and resistance than their non-modified equivalents. Finally, the initiation of FA polymerization by levulinic acid and p-toluene sulfonylhydrazine, respectively biobased and « latent » initiators has been studied. The second topic of thesis concerns a new type of fully bio-based epoxy resin synthesized from epoxidized vegetable oils. Linseed and soybean oils have both been copolymerized with a dicarboxylic acid as curing agent. A first fundamental work was to correlate the reactivity of copolymerization with the polymer structure and to link them with thermomechanical properties. The obtained thermosets have been used to prepare nanocomposites with sepiolite. Different methods of dispersion and/or modification of sepiolite conduct to diverse morphologies of nanofiller dispersions into the matrix.