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Blends based on polylactic acid (PLA), chitosan, and grape seed extract (GE) were prepared by extrusion and injection molding. The effect of chitosan (5% and 15% on PLA basis) and natural extract (1% on PLA basis) incorporated into the PLA host matrix was explored regarding the thermal and mechanical properties. GE showed antioxidant activity, as determined by the DPPH assay method. Chitosan and GE affect the degree of crystallinity up to 30% as the polysaccharide acts as a nucleating agent, while the extract reduces the mobility of PLA chains. The decomposition temperature was mainly affected by adding chitosan, with a reduction of up to 25 °C. The color of the blends was specially modified after the incorporation of both components, obtaining high values of b* and L* after the addition of chitosan, while GE switched to high values of a*. The elongation at break (EB) exhibited that the polysaccharide is mainly responsible for its reduction of around 50%. Slight differences were accessed in tensile strength and Young’s modulus, which were not statistically significant. Blends showed increased irregularities in their surface appearance, as observed by SEM analysis, corresponding to the partial miscibility of both polymers.

Der Ersatz fossiler Chemikalien durch Biomasse spielt eine wesentliche Rolle bei der Substitution konventioneller Kunststoffe und ebnet so den Weg für eine nachhaltigere Verpackungsindustrie. 2,5-Furandicarbonsäure (FDCA), dient als Ausgangsstoff für die Herstellung biobasierter Polymere und stellt eine vielversprechende Alternative dar, um die verschiedenen Nachhaltigkeitsprobleme zu lösen, die im Zusammenhang mit ihren fossilen Gegenstücken stehen. Um zu bestimmen, inwiefern Furan-basierte Polymere für den Einsatz als Lebensmittelverpackungen geeignet sind, wurde eine Importance-Performance-Analyse durchgeführt, um die wahrgenommene Wichtigkeit und tatsächliche Performance der Eigenschaften solcher Polymere zu bewerten, welche die Substitution von fossilen Verpackungsmaterialien unterstützen. Zusätzlich wurde eine Untersuchung potenzieller Diffusionslücken und Informationsasymmetrien zwischen Forschung und Industrie durchgeführt. Die Analyse wurde für drei Hauptkategorien durchgeführt, darunter ökologische, ökonomische und technische Eigenschaften. Die Ergebnisse zeigen, dass die meisten Eigenschaften als sehr wichtig erachtet werden, während ihre Performance in einigen Bereichen noch verbessert werden muss. Insbesondere ökonomische Faktoren erwiesen sich als großes Hindernis für den Diffusionsprozess Furan-basierter Polymere. Andere Hindernisse stehen im Zusammenhang mit ihrer ökonomischen Performance. Informationsasymmetrien wurden hauptsächlich im Zusammenhang mit den technischen Eigenschaften festgestellt. ExpertInnen aus Forschung und Industrie sind sich primär in Bezug auf die Leistung der thermomechanischen und Barriere-Eigenschaften uneinig. Dies führt zu der Schlussfolgerung, dass neben der Verbesserung der technische und ökologische Eigenschaften auch die ökonomische Attraktivität gesteigert werden muss, um die Lücke zwischen Theorie und Praxis zu schließen. Replacing fossil-based chemicals with biomass plays a crucial role regarding the substitution of conventional plastics, thus paving the way for a more sustainable packaging industry. 2,5-furandicarboxylic acid (FDCA) used as a feedstock for the production of fully bio-based polymers represents a promising alternative for tackling the various sustainability related issues associated with its petrochemical counterparts. To determine the applicability of furanic polymers as food packaging material, an importance performance analysis was carried out. The aim was to assess the perceived importance and actual performance of FDCA-based polymer properties potentially promoting the substitution of fossil-based polymeric materials. Additionally, an investigation on potential diffusion gaps and information asymmetries between the field of research and industry was conducted. The analysis was performed for three categorical main areas, including environmental, economic, and technical properties. The findings demonstrate that most of the properties are considered highly important, while their performance still needs to be improved in some areas. Especially properties related to the economic feasibility appeared to be major bottlenecks in the diffusion process of furanic polymers. Other identified barriers are linked to their environmental performance. Information asymmetries could mainly be identified in the context of the technical properties. Researchers and industry representatives seem to strongly disagree on the performance of the thermomechanical and barrier properties. This leads to the conclusion that, FDCA-based polymers require further improvements in terms of their technical property performance in order to be considered as an appropriate food packaging alternative. Also, their environmental performance needs to be revised and steps must be taken to enhance the economic attractiveness of furanic materials to bridge the existing gap between lab and market. Arbeit an der Bibliothek noch nicht eingelangt - Daten nicht geprüft Abweichender Titel laut Übersetzung des Verfassers/der Verfasserin Masterarbeit Universität Graz 2023

Dynamic-covalent nanosystems are applied as an approach to controllable self-organizing units. The robust but reversible nature of the dynamic-covalent bond imparts molecular recognition units for controlled self-assembly and stimulus-induced disassembly. In contrast to supramolecular interactions showing fast dynamics in the assembly and disassembly events the self-organizing features, dynamic-covalent systems are more challenging to control and there is much less information available. However, by exploiting the delicate balance between weak binding with high dynamics, and strong binding providing high stability of the formed bonds, the dynamic covalent materials reported herein provide many attractive features for i.e. drug delivery applications. In the first system of my thesis, dynamic covalent tags were prepared and optimized for the multivalent binding of boronic acid (BA) with catechols (CA). BA or CA residues are arranged by “coding” sequence recognition and controlled defect engineering with different dynamic-covalent binding oligomers. The pH was applied as an external stimulus inducing binding and release. In addition, the sequence recognition was demonstrated at the macromolecular level by conjugating the cytochrome c protein to a polyethylene glycol chain in a site-directed approach by dynamic covalent sequence recognition. Besides macromolecular conjugation, dynamic-covalent chemistry was also applied for the generation of stimulus-responsive materials. In this thesis, the reversible iron(III)-catechol interaction allowed pH-responsive binding and intramolecular folding of a polymer chain based on denatured human serum albumin. In this way, nanoparticles were formed by single chain folding, inspired by nature’s protein folding events. By rising the iron(III) concentration, intermolecular crosslinking dominates, resulting in stimuli-responsive and self-healing, rapid-gelating macroscopic hydrogels with a wide range of controllable mechanics. In combination with high adaptability, such characteristics provide attractive opportunities for tissue engineering. Based on the controlled interaction of stimuli-responsive dynamic covalent linkages, foldable macromolecular nanoparticles and smart macroscopic materials have been developed. The third dynamic system presented in my PhD thesis is based on a supramolecular tweezer-like molecule, which influences the macromolecular aggregation of peptide fibers and the nanoscopic structure of lipid membranes. In the investigation of the underlying mechanism, optimized tweezer molecules could serve as antiviral compounds against enveloped viruses. In these three systems, molecular design of dynamic covalent or supramolecular interactions allowed to control binding and disassembly events at the molecular level, which determines the resulting materials properties from the molecular to the macroscopic scale.

Eine Alternative, um von der Abhängigkeit von fossilen Rohstoffen wegzukommen, den CO2-Fußabdruck zu verringern und verschiedene End-of-Life-Szenarien zu ermöglichen, sind Biokunststoffe. Biokunststoffe sind entweder biobasiert, biologisch abbaubar oder beides, und es wurden bereits mehrere Arten mit vielversprechenden Eigenschaften entdeckt. Eine Sorge im Zusammenhang mit Biokunststoffen ist die Frage, ob sie für Lebensmittelverpackungen geeignet sind und wie wirksam sie Lebensmittel und Getränke schützen und eine angemessene Haltbarkeit gewährleisten. In dieser Literaturstudie wurde festgestellt, dass es nicht genügend Daten über die Auswirkungen von Biokunststoffen auf die Haltbarkeit von Lebensmitteln und damit mögliche Abfälle gibt. Bestimmte Materialien bieten eine hervorragende Lösung für bestimmte Produkte, wie z. B. Polymilchsäure (PLA) für atmungsaktive Produkte, aber dies kann nicht für alle Lebensmittel verallgemeinert werden. Es wurde eine Befragung von 12 schwedischen Unternehmen durchgeführt, um Informationen über die Wahrnehmung von Biokunststoffen zu erhalten und zu erfahren, unter welchen Bedingungen der Einsatz von Biokunststoffen wahrscheinlicher ist. Es nahmen drei verschiedene industrielle Stakeholder teil, Verpackungsunternehmen, Lebensmittelhersteller und Lebensmitteleinzelhändler. Als Limitationen wurden der Preis, die Verfügbarkeit, die Verarbeitbarkeit, die unterschiedliche chemische Struktur, die Recyclingfähigkeit und Kreislaufwirtschaft sowie die verfügbaren Informationen genannt. Die Unternehmen geben an, dass Haltbarkeit und Lebensmittelabfälle oft nicht in ihre Ökobilanzen einbezogen werde, da das sehr komplex ist. Jedoch sind sie sich einig, dass der Schutz von Lebensmitteln hohe Priorität hat. Die befragten Unternehmen verwenden derzeit nur so genannte Drop-in-Polymere, da diese die gleiche chemische Struktur wie die konventionellen Äquivalente haben. Es besteht kein Interesse an biologisch abbaubaren Materialien, da es noch kein Abfallmanagementsystem gibt und sie letztendlich verbrannt werden. Im Allgemeinen haben die Wiederverwertbarkeit und die Kreislaufwirtschaft im Moment eine höhere Priorität als Biokunststoffe. As environmental concerns are rising about fossil-based plastics, the urge to find solutions has increased and one possible solution to get away from the fossil dependency, decrease the carbon footprint and offer various End-of-Life scenarios are bioplastics. Bioplastics are either biobased, biodegradable, or both and several types with promising properties have been discovered already. One worry about bioplastics and if their application is feasible for food packaging applications, is how effectively they protect food and beverages and provide a decent shelf-life. Through a literature study, it was discovered that there is not enough data about the effect on shelf-life of bioplastics and thus potential food waste. Certain materials offer a great solution for specific products, such as polylactic acid (PLA) for respiring products, but this cannot be generalized. An interview with 12 Swedish companies was conducted to get information about the perception of bioplastics and under which conditions the implementation of bioplastics would be more likely. Three different industrial stakeholders took part, namely packaging companies, food manufacturers, and food retailers. The named barriers were price, availability, processability, the different chemical structure, recyclability, and possibility for a circular economy as well as available information. Companies struggle to include shelf-life and food waste into their life cycle assessments (LCAs), even though they agree that food protection is of high priority. The interviewed companies only use the so-called drop-in polymer bio-based PE at the moment, as it has the same chemical structure as its petrol-based equivalent. There is no interest in biodegradable materials because there is no waste management system yet and they end up being burned. In general, recyclability and a circular economy are of higher priority compared to bioplastics.

While the adhesion between synthetic materials has been rather well-studied experimentally and theoretically, there is still a lack of knowledge on bioadhesion, which could be tackled with biopolymer systems which could mimic biosurfaces, biotissues and bioadhesives. However, this idea is limited by the difficulty in designing a model structure and controlling the physical chemistry properties of biopolymer-made materials. Bioadhesion mechanisms can be tackled by studying the underwater adhesion between hydrogel adhesives and solid substrates modified by hydrogel thin films. This allows to separate interfacial contribution with molecular specific interactions and bulk contribution with viscoelastic properties to adhesion. First, a model system based on gelatins has been designed and underwater adhesion promoted by electrostatic interactions was investigated. On one side, stable surface-attached gelatin films with finely adjustable thickness and swelling were achieved using Cross-Linking and Grafting (CLAG) strategy. On the other side, dual-crosslinked gelatin hydrogel adhesives were synthesized by adding chemical crosslinks to physical gelatin networks. The microscopic structure of both physical and chemical crosslinks was well-controlled, with the determination of the chain length between crosslinks from shear modulus and phantom network model. Underwater adhesion measured by probe tack tests showed that dual-crosslinked gelatin hydrogels have the same adhesive properties at all temperatures even if their strength decreases with heating. We were also able to separate the effects of physical and chemical networks on adhesion. Second, the underwater adhesion between double-networks containing carrageenan and solid substrates modified by micro-patterned hydrogels was investigated. It was shown that the smaller the micro-patterns the higher the adhesion energy. This work has provided an insight of the physico-chemical and physical parameters that control underwater adhesion of biopolymers systems such as the bulk viscoelastic properties, the charge and the topography of the surface. It would help for better understanding bioadhesion and designing underwater adhesives., Alors que l'adhésion entre matériaux synthétiques a été plutôt bien étudiée expérimentalement et théoriquement, les mécanismes de bioadhésion sont encore très peu compris. Une manière de les aborder serait d’utiliser des systèmes biopolymères qui pourraient imiter biosurfaces, biotissus et bioadhésifs. Cependant, cette idée est confrontée à la difficulté de concevoir une structure modèle et de contrôler les propriétés physico-chimiques des matériaux fabriqués à partir de biopolymères. Les mécanismes de bioadhésion peuvent être mieux compris en étudiant l'adhésion en milieu immergé entre adhésifs hydrogels et substrats solides modifiés par des films minces d'hydrogel. Cela permet de séparer la contribution interfaciale avec des interactions spécifiques moléculaires et de la contribution du volume avec les propriétés viscoélastiques à l'adhésion. Dans un premier temps, nous avons conçu un système modèle avec de la gélatine et noua avons étudié l'adhésion en milieu immergé favorisée par des interactions électrostatiques. D'une part, des films stables de gélatine attachés en surface d’épaisseur et de gonflement finement ajustables ont été réalisés en utilisant la stratégie Cross-Linking and Grafting (CLAG). D'autre part, des adhésifs hydrogels de gélatine à double réticulation ont été synthétisés en ajoutant des réticulations chimiques aux réseaux de gélatine physiques. La structure microscopique des réticulations physique et chimique a été bien contrôlée, avec la détermination de la longueur de chaîne entre les réticulations à partir du module de cisaillement et du modèle de réseau fantôme. L'adhésion en milieu immergé mesurée par des tests de probe-tack a montré que les hydrogels de gélatine à double réticulation ont les mêmes propriétés adhésives quelle que soit la température, même si leur résistance diminue avec le chauffage. Nous avons également été en mesure de séparer les effets des réseaux physiques et chimiques sur l'adhésion. Dans un deuxième temps, nous avons étudié l'adhésion en milieu immergé entre des réseaux doubles contenant du carraghénane et des substrats solides modifiés par des micro-motifs d’hydrogels. Il a été démontré que plus les micro-motifs sont petits, plus l'énergie d'adhésion est élevée. Ce travail a fourni un aperçu des paramètres physico-chimiques et physiques qui contrôlent l'adhésion en milieu immergé des systèmes biopolymères tels que les propriétés viscoélastiques en volume, la charge et la topographie de la surface. Il aidera à mieux comprendre la bioadhésion et à concevoir des adhésifs efficaces en milieux aqueux.

Cereals are subject to contamination by pathogenic fungi, which damage grains and threaten the public health with their mycotoxins. Recently, the raise of public and political awareness concerning environmental issues tend to limit the use of traditional fungicides against these pathogens in favour of eco-friendlier alternatives. In this framework, this thesis work aims to create a formulation based on renewable products in order to limit the fungal development and control the production of mycotoxins from cereal fungi. Our work exploits the remarkable properties of three compounds: the chitosan, a chitin derived biopolymer, the tetrahydrocurcumin (THC), a curcumin derivative, and plant extracts. In a first step, we studied and characterise the physicochemical properties of different chitosans. Chitosan solutions were shown to reduce the mycelial growth of a target model fungi Fusarium graminearum, and to divide by 2 the accumulation of mycotoxins. In addition, we showed that this biopolymer was able to maintain its antifungal properties as a form of a coating. In a second step, we focused on different plant extracts with antimicrobial activities. THC was able to inhibit the toxin production and a maritime pine by-product showed its potential to control the fungal growth. The combination of the THC or the wood extract with chitosan was then studied to increase the efficiency of the formulation. To this end, a significant work was made to increase the solubility of THC in water by forming an inclusion complex in cyclodextrins or by protecting it in starch or chitosan particles. In particular, we showed that the addition of pine extracts to a chitosan-based solution can double the effectiveness of the formulation.; Les cultures céréalières sont sujettes aux invasions de champignons pathogènes, ce qui altère la qualité des grains et pose un problème de santé publique, en raison de mycotoxines potentiellement contenues dans ces grains. Face à la prise de conscience publique et politique de la nécessité d’inclure la composante environnementale dans nos modes de consommation et de production, les fongicides synthétiques traditionnels se voient petit à petit remplacés par des alternatives plus « vertes ». Dans ce contexte, ce travail de thèse a pour but de créer une formulation à base de produits renouvelables, pour contrôler le développement et la production de toxines d’espèces fongiques pathogènes. Ce travail exploite les propriétés remarquables de trois composés : le biopolymère de chitosane, dérivé de la chitine, la tétrahydrocurcumine (THC), un dérivé de curcumine, et des extraits de pins et de vigne. Les propriétés physico-chimiques des chitosanes ont tout d’abord été caractérisées. Ces solutions de chitosanes présentent des effets antifongiques prometteurs réduisant la croissance mycélienne du champignon modèle cible Fusarium graminearum et divisant sa production de mycotoxines de plus moitié. Un des principaux atouts de ce biopolymère réside dans le fait qu’il conserve ses propriétés antifongiques sous forme d’enduction. Des extraits végétaux possédant des activités antimicrobiennes ont ensuite été étudiés. Premièrement, la THC inhibe la production de toxines et est donc combinée avec du chitosane. Afin d’accroître la solubilité dans l’eau et l’efficacité de la THC, des complexes d’inclusion ont été formés avec des cyclodextrines. De même, cette THC a été encapsulée dans d’autres matrices de biopolymères variés, tels que l’amidon ou le chitosane. Deuxièmement, les extraits issus de ressources locales de pins maritimes et de vignes démontrent eux aussi des effets antifongiques et anti-mycotoxigéniques. En particulier, l’addition d’un de ces extraits, celui d’écorce de pin maritime, à une formulation de chitosane double l’efficacité de ce dernier contre le développement du mycélium.

Hydrogels have sparked great interest in life sciences as they are an ideal material class for many medical applications such as drug delivery and tissue engineering. In particular, the development of hybrid hydrogel materials is a major focus of current research efforts, since the combination of natural (macro-)molecules with synthetic compounds allows for engineering of application-oriented conjugates with complementing properties. Despite extensive research, many proposed hydrogels suffer from heterogeneity regarding their chemical composition, which complicates precise adjustment of their physical and pharmacological properties. Chemically defined hydrogels that are able to serve as biocompatible and -degradable cell matrices featuring controlled and rapid gelation, excellent self-healing, a well-defined and simple introduction of functionalities, as well as general stability during cell cultivation are currently still difficult to achieve. In this Doctoral thesis, the design and preparation of novel hybrid hydrogels mainly in the context of tissue engineering is explored, with an aim to improve material properties and incorporate the above-mentioned features in a single hydrogel system. The hydrogels are tested as artificial cell matrices for regeneration of diseased or traumatized tissue, with a potential modulation of endogenous metabolic processes via the delivery of therapeutically active compounds. By creating hybrid hydrogels, this work bridges existing gels made from either fully synthetic or natural systems. Taking the architecture of the natural ECM as an inspiration, the development of novel hybrid hydrogels is explored by employing supramolecular cross-linking of covalent backbones to overcome the current limitations of conventional hydrogels. Furthermore, this thesis provides a detailed investigation of material properties such as gelation, mechanical properties, release of active ingredients degradability and compatibility with different cell types. Here, biopolymers in combination with programmable structural elements such as DNA and peptides are investigated. Nucleic acids are becoming increasingly important as versatile building blocks for next generation hydrogel materials. Within this work, a comprehensive and critical overview of the available examples of DNA-based hydrogels and their potential applications in life sciences is provided, describing how the structure of DNA materials influences their various properties. The most important synthetic concepts for the production of all-DNA hydrogels as well as various DNA-based hybrids are described and comprehensively reviewed in view of new concepts, properties, and applications. Excellent programmability and perfect sequence control are offered by DNA, making it an appealing candidate as a supramolecular cross-linker. However, to achieve a final material that is well-defined, all hydrogel components need to be produced with a high level of precision, including the covalent backbone. Denatured proteins, such as human serum albumin (HSA) represent a new class of precision polymers that have a pre-defined sequence and chain length and different functional groups for further chemical modifications. The combination of both materials for the production of highly defined hydrogels for biomedicine is investigated. In this context, the applicability of protein-DNA hydrogels for spatiotemporally controlled release of therapeutically active compounds is successfully demonstrated. To prepare the backbone of these hybrid hydrogels, HSA is transferred into a brush-like protein-derived precision copolymer. Subsequently, physical hydrogels are formed by sequence-specific DNA hybridization of backbone-grafted DNA tags with small, complementary, dendritic DNA linkers, which can simultaneously introduce therapeutically active compounds into the gel. In this way, a rapid, highly specific and stable loading as well as controlled release of DNA-tagged bioactive cargo is realized. In this context, deoxyribonuclease triggered C3 toxin release allows efficient and specific inhibition of osteoclast formation and bone resorption without affecting osteoblastic differentiation and mineralization in vitro, confirming the suitability for local treatment of bone diseases such as osteoporosis via local drug delivery on a controlled time scale. In a second example for hybrid hydrogels, self-assembling peptides (SAPs) capable of forming nanofibrous structures instead of DNA strands are implemented as supramolecular cross-linkers. While these SAP-based systems do not reach the same level of programmability as DNA, they are much easier and more cost-effective to synthesize on larger scale and still allow the preparation of highly defined 3D materials. Additionally, the formed peptide nanofibrils (PNFs) promise improved biological performance, since they resemble the fibrous morphology of natural ECM. Here, pH-responsive, amphiphilic peptide gelators, so-called depsi peptides, are created and investigated for their ability to self-assemble into various nanostructures and finally induce hydrogel cross-linking. These depsi peptides are unable to assemble into PNFs under acidic conditions, whereas upon increasing the pH to neutral, an intramolecular O–N–acyl migration reaction causes instantaneous PNF formation with β-sheet structures. Conjugating depsi peptides onto the HSA-derived backbone transfers the beneficial pH-responsive aggregation behavior onto the hybrid. At higher mass concentration, the hybrid forms a highly porous hydrogel with instantaneous gelation at neutral pH. The PNF cross-linked hybrids show thixotropic behavior with ultra-fast, near-quantitative recovery after multiple shear cycles. The gels are injectable and their mechanical properties can be adjusted by changing the number of peptide grafts or the solid content. The material is shown to support the survival and growth of various cell types. Even the active migration of endothelial cells into the material after topological seeding is demonstrated, being a distinguishing feature compared to many other types of hydrogels. In view of all these findings, the pH-responsive PNF cross-linked hydrogel offers excellent potential as a regenerative scaffold for biomedicine. To further evolve the depsi peptides as controllable nanomaterial building blocks, the responsiveness of assembly is extended to other physiologically relevant stimuli besides pH, while methionine-containing peptides provide an orthogonal “responsive unit” for controlled disassembly under oxidative conditions. To create a material that combines the scalability of peptides with the programmability of DNA, dynamic covalent interactions between boronic acids (BAs) and catechols (CAs) are developed into synthetic nucleobase analogs to encode molecular recognition in a stimuli-responsive way. Simulating DNA by creating and arranging BA or CA residues along a defined peptide backbone, their complementary binding is analyzed, and cytochrome c is functionalized with polyethylene glycol using trivalent tag-conjugated derivatives, indicating that such a synthetic code may also allow to program dynamic macromolecular architectures.

The use of membrane filtration is now widely implemented in the separation processes and is used in a large range of application sectors, such as the water treatment, the pharmaceutical or the food industries. Among the separation technologies, membrane filtration has the advantages to be energy-efficient, to not require any additional chemicals and to be easily scalable. However, the commonly phase inversion processes used to fabricate polymeric membranes can be considered as harsh for the environment. Thus, they require the use of fossil-based polymers, known to cause the depletion of non-renewable resources and environmental pollutions, and also request large amount of toxic solvents. The objective of this study is to fabricate more sustainable membranes. Herein, the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) has been used as biobased and biodegradable membrane material. Different phase inversion techniques have been studied. The membranes have been prepared either by evaporation induced phase separation or by non-solvent induced phase separation. The biopolymer-based membranes were successfully produced using a green solvent (the Cyrene™). By studying the effects of the dope solution composition and fabrication parameters, the membrane microstructure has been tailored. The membranes show interesting performances related to microfiltration and pervaporation applications., Les procédés membranaires sont aujourd'hui largement utilisés dans différents secteurs d'application, comme le traitement de l'eau ou les industries pharmaceutique et agroalimentaire. En comparaison aux autres technologies de séparation, la filtration membranaire a l'avantage d'être économe en énergie, de ne pas nécessiter l'utilisation de produits chimiques supplémentaires et d'être facilement mise à l'échelle du procédé. Cependant, les procédés d'inversion de phase, couramment utilisés pour la fabrication de membranes polymères, sont souvent nocifs pour l'environnement. En effet, ils utilisent majoritairement des polymères issus de ressources fossiles, aussi connus pour être la cause de pollutions environnementales, et requièrent des quantités importantes de solvants toxiques. Cette thèse vise à contribuer au développement de membranes plus respectueuses de l'environnement. Ici, le poly(3-hydroxybutyrate-co-3-hydroxyvalerate) a été utilisé comme matériau membranaire biosourcé et biodégradable. Les membranes ont été fabriquées au moyen de différentes techniques, l'inversion induite par évaporation du solvant et l'inversion de phase inuite par addition d'un non-solvant. Les membranes en biopolymère ont été fabriquées avec succès en utilisant un solvant vert (le Cyrène™). Grâce à l'étude de l'influence de la composition du collodion ainsi que de celle des paramètres de mise en oeuvre, la microstructure membranaire a pu être contrôlée. Les membranes montrent des performances prometteuses pour des applications en microfiltration et pervaporation.

The nanoprecipitation technique is a reliable route to synthesize oil filled nanocapsules with shells made of hydrophilic polymers such as polysaccharides and vinyl based glycopolymers in a one pot procedure. Thanks to their biocompatibility, biodegradability and tunable biological activity, proteins are another promising class of materials for encapsulation purposes. However, the generation of proteinaceous nanocapsules by nanoprecipitation has never been reported. In this context, the main objective of this PhD was to evaluate the potential of a family of proteins, the Suckerins, in nanoprecipitation processes. Suckerins are a family of proteins found in the sucker ring teeth of the giant Humboltd squid with promising biomedical applications. These proteins possess a modular, block copolymer like structure capable of forming β-sheets responsible for good mechanical properties. The suckerin proteins are not soluble at a pH range between 5 and 10, a requirement of the nanoprecipitation technique. However, they can be solubilized using aqueous buffers at pH 3 containing acetic acid. Other ways of precipitating the protein were explored in this manuscript with salt shifting using ammonium persulphate as coacervation agents being capable of generating 100 nm nanoparticles. These nanoparticles presented the β sheet secondary structure which resulted in Young modulus in the GPa range. A fusion protein that could be solubilized in aqueous solutions at pH 7, and therefore be used in the nanoprecipitration process, was recombinantly produced. The protein (suckerin silk) is formed by a central squid suckerin-derived peptide block that provides structural stability and both termini from silk fibroins that make the modular protein highly soluble at physiological pH. This molecular design allowed the fabrication of hexadecane and miglyol filled nanocapsules with suckerin silk shells and sizes in the range 190 – 250 nm. Finally, aiming to encapsulate an anti cancer drug in glycogen nanocapsules we developed a protocol where the nanoprecipitation process is used to generate glycogen coated prodrug nanoparticles., La technique de nanoprécipitation est une méthode simple et reproductible pour la synthèse de nanocapsules à coeur huileux recouvertes d’une enveloppe de polymères hydrophiles réticulés (polysaccharides, glycopolymères vinyliques…) en une seule étape. Grâce à leur biocompatibilité, leur biodégradabilité et leur activité biologique adaptables, les protéines constituent une autre grande famille de biopolymères d’intérêt pour des applications dans le domaine de l’encapsulation. Cependant, la production de nanocapsules protéiques par nanoprécipitation n’a jamais été décrite. Dans ce contexte, l’objectif principal de ce travail de thèse a été l’évaluation du potentiel d’une famille de protéines, les Suckerines, pour le procédé de nanoprécipitation. Les Suckerines sont une famille de protéines issues des dents décorant les ventouses du calamar géant Humboldt avec de prometteuses applications dans le domaine biomédical. Ces protéines possèdent une structure modulaire de type copolymère à bloc capable de former des feuillets bêta conférant de bonnes propriétés mécaniques. Les suckerines étant solubles dans une solution tampon composée d’acide acétique (pH 3) mais fortement agrégées dans les conditions de pH (valeurs comprises entre 5 et 10) classiquement utilisées pour la préparation de nanocapsules à coeur huileux par basculement de solvant, nous avons finalement choisi d’explorer la nanoprécipitation des protéines par salt shifting et donc la préparation de nanoparticules protéiques. L’utilisation du persulfate d’ammonium comme agent de coacervation et précurseur de radicaux et du tris(2,2′ bipyridyl)dichlororuthenium(II) hexahydrate a permis de produire des nanoparticules de suckerine de tailles modulables (100-185 nm de diamètre). Ces nanoparticules présentent des structures secondaires type feuillets bêta qui sont à l’origine du module de Young très élevé observé pour ces nano-objets (de l’ordre de grandeur du GPa). Une protéine de fusion, soluble en milieu aqueux à pH 7 a spécialement été conçue par voie de recombinaison dans le but de générer des nanocapsules protéiques par nanoprécipitation. Cette protéine (suckerine-soie) est formée d’un bloc central de peptide dérivé de suckerine de calamar promouvant une stabilité structurelle et deux blocs terminaux issus de fibroïnes de soie qui permettent à la protéine de fusion d’être soluble à un pH physiologique. Ce design moléculaire a permis la fabrication de nanocapsules remplies respectivement de hexadécane ou de miglyol avec une enveloppe de suckerine-soie et de tailles de l’ordre de grandeur de 190 à 250 nm. Finalement, aspirant à encapsuler un principe actif anti-cancéreux dans les nanocapsules à base de glycogène, nous avons développé un protocole où la méthode de nanoprécipitation est utilisée pour produire des nanoparticules de prodrogue entourés de glycogène.

Lignin is a polymeric constituent of vascular plants’ pectocellulosic walls. It is a by-product, poorly upgraded from pulp and paper, and biorefinery industries. To evaluate their potential in agrocomposites field, commercial lignins (sodium lignosulfonates and Kraft lignin) were processed along with corn cob, an agro-industrial residue used hereby as a natural fibre. Firstly, a compression-moulding process allowed the combination of hydrated sodium lignosulfonates and corn cob particles. The impact of three factors (particle size, fibre content, and compacting pressure) on compressive mechanical properties was measured. Although sodium lignosulfonates cross-linking by commercial laccases was highlighted in solution, addition of such enzymes to agrocomposites formulations did not improve their flexural strength (maximum value of 5.3 MPa). The acoustic insulation properties of agrocomposites (sound transmission loss of 60 dB) and their thermal conductivity of 0.143 W.m - 1.K -1 may suggest applications in the building sector. Secondly, nine formulations of bio-based materials were developed by twin-screw extrusion, and then injection moulding, combining a bio-based thermoplastic polymer matrix (polylactic acid and/or poly(butylene succinate)) with technical lignins (2.5 to 20% (m/m) Kraft lignin or sodium lignosulfonates), and corn cob particles (5 to 19% (m/m)). The addition of Kraft lignin led to increased hardness of the materials up to 50%, and more hydrophobicity compared to polylactic acid. Nevertheless, their mechanical strengths decreased (by a maximum of 40%), and materials exhibited a more brittle fracture profile. In the presence of corn cob, transfer of forces from matrix to fibres was not ideal since de-bonding was detected at the interfaces under irreversible flexural stress. However, these bio-based materials exhibited mechanical, and thermal properties that made them suitable for synthetic plastics substitution while adding value to by-products of agricultural, and forest industries.; La lignine est un polymère constitutif des parois pectocellulosiques des plantes vascularisées. Elle est un sous-produit, peu valorisé, de l’industrie papetière et du bioraffinage. En vue d’évaluer leur potentiel dans la filière des agrocomposites, des lignines commerciales (lignosulfonates de sodium et lignine Kraft) ont été mises en oeuvre en présence de rafle de maïs, une agro-ressource utilisée ici comme renfort fibreux naturel. Dans un premier temps, un procédé de compression-moulage a permis d’associer des lignosulfonates de sodium hydratés à des particules de rafles de maïs. L’impact de trois facteurs (granulométrie, taux de fibres et pression de compactage) sur les propriétés mécaniques en compression des agrocomposites a été mesuré. Bien que la réticulation des lignosulfonates de sodium par des laccases commerciales ait été mise en évidence en solution, l’ajout de ces enzymes aux formulations d’agrocomposites n’a pas amélioré leurs résistances mécaniques en flexion (valeur maximale de 5,3 MPa). Leurs propriétés d’isolation acoustique (indice d’affaiblissement acoustique de 60 dB) et leur conductivité thermique de 0,143 W.m - 1.K -1 permettent d’envisager des applications pour le secteur du bâtiment. Dans un second temps, neuf formulations de matériaux bio-sourcés ont été développées en associant par extrusion bi-vis puis injection plastique, une matrice polymère thermoplastique (acide polylactique et/ou poly(butylène succinate)), des lignines techniques (2,5 à 20 % (m/m) de lignine Kraft ou lignosulfonates de sodium) et/ou des particules de rafles de maïs (5 à 19 % (m/m)). L’ajout de lignine Kraft a permis d’augmenter la dureté des matériaux jusqu’à 50 % et de les rendre plus hydrophobes que l’acide polylactique. Néanmoins, les résistances mécaniques ont été diminuées (maximum 40 %) et les matériaux ont présenté des profils de rupture plus fragiles. En présence de rafles de maïs, le transfert des efforts de la matrice vers les fibres n’était pas optimal car des décohésions ont été détectées aux interfaces à la suite de sollicitations irréversibles en flexion. Ces matériaux bio-sourcés ont toutefois présenté des propriétés mécaniques et thermiques les rendant aptes à se substituer à des plastiques synthétiques tout en conférant une valeur ajoutée à des sous-produits d’industries agricole et forestière.

Die vorliegende Arbeit befasst sich mit der Entwicklung von Haftvermittlersystemen für eine verbesserte Faser-Matrix-Adhäsion in Holzfurnier/Biopolyethylen-Verbundwerkstoffen. Dabei wird zunächst die Charakterisierung der zu modifizierenden Rotbuchenfurnieroberfläche sowie die Herstellung von Holzfurnier/Biopolyethylen-Verbundwerkstoffen ohne Haftvermittler vorgestellt. Um die Kompatibilität der beiden Werkstoff zu erhöhen, wurden verschiedene Konzepte zur Haftförderung entwickelt und appliziert. Der Beschichtungsprozess von unterschiedlichen Formulierung wie Poly(N-vinylformamid-co-vinylamin) und strukturell verschiedenen Maleinsäureanhydridcopolymeren auf dem Holzfurnier wurde systematisch untersucht. Die Charakterisierung der beschichteten Rotbuchenfurnieroberfläche erfolgte unter anderen mit Hilfe von Kontaktwinkelmessungen, Röntgenphotoelektronenspektroskopie und elektronen-mikroskopischen Aufnahmen. Die Anwendung der haftvermittelnden Polymere auf dem Holzwerkstoff ermöglicht die Herstellung von Holzfurnier/Biopolyethylen-Verbundwerkstoffen mit erhöhten mechanischen Kennwerten wie beispielsweise dem E-Modul und der Zugfestigkeit. Das Konzept der simultanen Zwillingspolymerisation wurde ebenfalls zur Haftförderung zwischen den Ausgangsmaterialien eingesetzt. Dafür wurden verschiedene neue, funktionale Zwillingsmonomere synthetisiert und anschließend deren Polymerisationsverhalten und die resultierenden Hybridmaterialien charakterisiert. Durch Applikation von verschiedenen Zwillingsmonomermischungen auf der Holzfurnieroberflächen konnten in Kombination mit Biopolyethylen kompatible und stabile Verbundwerkstoffe mit erhöhten mechanischen Eigenschaften erzielt werden.

Maßgeschneiderte Kunststoffe sind heute extrem vielseitig einsetzbar, ihre Anwendungen reichen von Lebensmittelverpackungen, über dünne feuerfeste Dämmplatten und körperresorbierbare Nahtmaterialien bis hin zu Motorenaufhängungen im Automobil. Um diese Bandbreite an Anwendungen zu erreichen, werden Kunststoffe mit sehr unterschiedlichen, aber auch sehr spezifischen Eigenschaften benötigt. Ermöglicht wird diese Einstellung von Eigenschaften durch das Beimischen von Additiven und Füllstoffen. Im Laufe der letzten Jahrzehnte kam es seitens der Verbraucher zu einem deutlich gesteigerten Interesse an Biopolymeren, weshalb zunehmend auch natürliche und biologisch abbaubare Zuschlagstoffe in den Fokus geraten. Auch die Umweltfreundlichkeit der jeweiligen Herstellungsmethoden für Additive, sowie des gesamten Herstellungsprozesses sind zu entscheidenden Aspekten geworden. Obgleich das Thema in der Forschung teilweise bereits seit den 1990ger Jahren präsent ist, rückt die Thematik in den letzten Jahren weiter in den Vordergrund, vor allem auch durch die zunehmende Reife an Biokunststoffen. Der Überblicksartikel beleuchtet kurz den aktuellen Stand und neuere Entwicklungen.

Lignin is a polymeric constituent of vascular plants’ pectocellulosic walls. It is a by-product, poorly upgraded from pulp and paper, and biorefinery industries. To evaluate their potential in agrocomposites field, commercial lignins (sodium lignosulfonates and Kraft lignin) were processed along with corn cob, an agro-industrial residue used hereby as a natural fibre. Firstly, a compression-moulding process allowed the combination of hydrated sodium lignosulfonates and corn cob particles. The impact of three factors (particle size, fibre content, and compacting pressure) on compressive mechanical properties was measured. Although sodium lignosulfonates cross-linking by commercial laccases was highlighted in solution, addition of such enzymes to agrocomposites formulations did not improve their flexural strength (maximum value of 5.3 MPa). The acoustic insulation properties of agrocomposites (sound transmission loss of 60 dB) and their thermal conductivity of 0.143 W.m - 1.K -1 may suggest applications in the building sector. Secondly, nine formulations of bio-based materials were developed by twin-screw extrusion, and then injection moulding, combining a bio-based thermoplastic polymer matrix (polylactic acid and/or poly(butylene succinate)) with technical lignins (2.5 to 20% (m/m) Kraft lignin or sodium lignosulfonates), and corn cob particles (5 to 19% (m/m)). The addition of Kraft lignin led to increased hardness of the materials up to 50%, and more hydrophobicity compared to polylactic acid. Nevertheless, their mechanical strengths decreased (by a maximum of 40%), and materials exhibited a more brittle fracture profile. In the presence of corn cob, transfer of forces from matrix to fibres was not ideal since de-bonding was detected at the interfaces under irreversible flexural stress. However, these bio-based materials exhibited mechanical, and thermal properties that made them suitable for synthetic plastics substitution while adding value to by-products of agricultural, and forest industries., La lignine est un polymère constitutif des parois pectocellulosiques des plantes vascularisées. Elle est un sous-produit, peu valorisé, de l’industrie papetière et du bioraffinage. En vue d’évaluer leur potentiel dans la filière des agrocomposites, des lignines commerciales (lignosulfonates de sodium et lignine Kraft) ont été mises en oeuvre en présence de rafle de maïs, une agro-ressource utilisée ici comme renfort fibreux naturel. Dans un premier temps, un procédé de compression-moulage a permis d’associer des lignosulfonates de sodium hydratés à des particules de rafles de maïs. L’impact de trois facteurs (granulométrie, taux de fibres et pression de compactage) sur les propriétés mécaniques en compression des agrocomposites a été mesuré. Bien que la réticulation des lignosulfonates de sodium par des laccases commerciales ait été mise en évidence en solution, l’ajout de ces enzymes aux formulations d’agrocomposites n’a pas amélioré leurs résistances mécaniques en flexion (valeur maximale de 5,3 MPa). Leurs propriétés d’isolation acoustique (indice d’affaiblissement acoustique de 60 dB) et leur conductivité thermique de 0,143 W.m - 1.K -1 permettent d’envisager des applications pour le secteur du bâtiment. Dans un second temps, neuf formulations de matériaux bio-sourcés ont été développées en associant par extrusion bi-vis puis injection plastique, une matrice polymère thermoplastique (acide polylactique et/ou poly(butylène succinate)), des lignines techniques (2,5 à 20 % (m/m) de lignine Kraft ou lignosulfonates de sodium) et/ou des particules de rafles de maïs (5 à 19 % (m/m)). L’ajout de lignine Kraft a permis d’augmenter la dureté des matériaux jusqu’à 50 % et de les rendre plus hydrophobes que l’acide polylactique. Néanmoins, les résistances mécaniques ont été diminuées (maximum 40 %) et les matériaux ont présenté des profils de rupture plus fragiles. En présence de rafles de maïs, le transfert des efforts de la matrice vers les fibres n’était pas optimal car des décohésions ont été détectées aux interfaces à la suite de sollicitations irréversibles en flexion. Ces matériaux bio-sourcés ont toutefois présenté des propriétés mécaniques et thermiques les rendant aptes à se substituer à des plastiques synthétiques tout en conférant une valeur ajoutée à des sous-produits d’industries agricole et forestière.

Eine Welt ohne Kunststoffe ist heutzutage nahezu unvorstellbar. Ihre vielseitigen Eigenschaften tragen dazu bei, dass Kunststoffe nicht nur in der Verpackungsindustrie, sondern auch in vielen anderen Bereichen individuell eingesetzt werden können. Daraus resultierend nimmt der Bedarf an Kunststoffen jährlich zu. Auch der Biokunststoffmarkt steigt seit einigen Jahren immer weiter. Reine Biopolymere haben im Vergleich zu konventionellen Kunststoffen eher schlechte Barriereeigenschaften gegenüber Sauerstoff und Wasserdampf. Daher können diese aufgrund ihrer Eigenschaften vor allem im Lebensmittelbereich meist nicht mit anderen Polymeren mithalten. Demzufolge wird versucht Biokunststoffe mit Beschichtungen zu kombinieren, um die Einsatzmöglichkeiten auszudehnen. Diese Arbeit beschäftigt sich mit der Frage ob es möglich ist, eine Kombination aus Biopolymer und Beschichtung zu finden, welche einem sauerstoffempfindlichen Lebensmittel Schutz bieten würde. Dazu wurden zwei unterschiedliche Beschichtungsmöglichkeiten verwendet. Die Beschichtungen wurden anschließend analysiert und teilweise bezüglich ihrer Sauerstoffpermeabilität gemessen. Aus den ausgewerteten Ergebnissen und den daraus entstandenen Erkenntnissen wurden weitere Alternativen theoretisch angeführt. Abschließend wurden alle Resultate zusammengefasst und diskutiert. Today, a world without plastics is almost unimaginable. Their versatile properties contribute to the fact that plastics can be used individually not only in the packaging industry but also in many other areas. As a result, the demand for plastics is increasing every year. The bioplastics market has also been growing steadily for several years. In contrast to conventional plastics, pure biopolymers have rather poor barrier properties against oxygen and water vapour. Therefore, due to their properties, especially in the food sector, they are usually not able to compete with other polymers. Consequently, attempts are being made to combine bioplastics with coatings in order to expand the range of possible applications. The aim was to answer the question whether it is possible to find a combination of biopolymer and coating that would offer protection to an oxygen-sensitive food. Two different coating options were used for this thesis. The coatings were then analysed and partially measured with respect to their oxygen permeability. Based on the evaluated results and the resulting findings, further alternatives were presented theoretically. Concluding, all results were summarized and discussed.

Das Ziel dieser Diplomarbeit ist es, einen Überblick über Biokunststoffe als Alternative zu konventionellen Kunststoffen zu geben. Zu Beginn wird die geschichtliche Entwicklung von Biokunststoffen dargelegt. Der Schwerpunkt der Arbeit liegt auf biologisch abbaubaren und biobasierten Kunststoffen, daher wird allgemein der biologische Abbauprozess beschrieben. Nach der Abgrenzung verschiedener Begrifflichkeiten folgt ein Vergleich der Vor- und Nachteile von nachwachsenden und petrochemischen Rohstoffen.Die Biokunststoffe Polylactid, Polyhydroxyalkanoate und Stärke werden ausführlicher beschrieben in Hinblick auf deren Herstellung, chemische Strukturen und Eigenschaftsprofile. Bei den Eigenschaften liegt der Fokus auf dem Vergleich mit konventionellen Kunststoffen und möglichen Substitutionspotenzialen. Ein weiterer Schwerpunkt liegt auf der Nachhaltigkeit und der Nachhaltigkeitsanalyse der ausgewählten Biokunststoffe.Der letzte Teil beschäftigt sich mit der Umsetzung der Thematik in der Schule. Durch die Lehrpläne wird aufgezeigt, dass man mit Kunststoffen und Biokunstoffen viele Bereiche und Konzepte der Schule gut abdecken kann. Als Abschluss werden mögliche Unterrichtseinstiege und Experimente vorgestellt. The objective of this paper is to give an overview of bioplastics as an alternative for conventional plastics. At the beginning, the historical development of bioplastics is described. Because the key aspect of this paper is about biodegradable and bio-based plastics, the general organic degradation process is described. After distinguishing the terms, a comparison of the advantages and disadvantages of renewable and petrochemical resources follows.The bioplastics Polylactide, Polyhydroxyalkanoates and starch are described more precisely regarding their production, chemical structures and characteristics. The focus regarding characteristics is the comparison with conventional plastics and the substitution potential. Another key aspect is the sustainability and the sustainability analysis of the selected bioplastics.The last part is about the implementation of the subject in school. Syllabuses are used to demonstrate that plastics and bioplastics cover a wide range of topics and concepts in school. At the end a variety of potential introductions in class and experiments are presented. Arbeit an der Bibliothek noch nicht eingelangt - Daten nicht geprüft Abweichender Titel laut Übersetzung des Verfassers/der Verfasserin Karl-Franzens-Universität Graz, Diplomarbeit, 2020 (VLID)5215271

Kunststoffe sind in der Verpackungsbranche aber auch in vielen anderen Bereichen, nicht mehr weg zu denken. Aufgrund ihrer vielseitigen Eigenschaften sind sie individuell einsetzbar. Der Verbrauch an Kunststoffen steigt seit einigen Jahren kontinuierlich an, dabei haben auch Biokunststoffe vermehrte Aufmerksamkeit auf sich gezogen. Als pures Material können die Eigenschaften von Biopolymere in manchen Fällen nicht mit denen der konventionellen Polymere mithalten. Um das Potential der Biokunststoffe auszubauen ist man gezwungen, die Beschaffenheit der Materialien mit Beschichtungen zu verbessern. Diese Arbeit beschäftigt sich mit einigen aktuell vorhandenen Prozessen, um die Eigenschaften von Polymeren zu verändern. Ziel war es dabei einen Überblick an Beschichtungsmöglichkeiten für Biopolymere zu geben. Dabei wurden häufig eingesetzte Methoden aber auch potentielle Alternativen betrachtet. Analysiert wurden dabei die unterschiedlichen Prozesse der Beschichtung. Hierbei wurden die verschiedenen Rohstoffe, die zur Herstellung von Beschichtungsmitteln eingesetzt werden, betrachtet. In weiterer Folge wurden die möglichen Vorbehandlungen dargelegt. Abschließend wurden die eigentlichen Beschichtungsprozesse behandelt. Plastics have become indispensable in the packaging industry, but also in many other areas. Due to their versatile properties they can be used individually. The consumption of plastics has been increasing continuously for several years. Bioplastics have also attracted increasing attention. As a pure material, the properties of biopolymers cannot compete with those of conventional polymers sometimes. In order to develop the potential of bioplastics, it is necessary to improve the properties of materials with coatings. This thesis deals with some currently existing processes to change the properties of polymers. The aim was to give an overview of coating possibilities for biopolymers. Frequently used methods but also potential alternatives were considered. The different processes of coating were analysed. The different raw materials used for the production of coating agents were considered. In the following, the possible pre-treatments were presented. Finally, the actual coating processes were discussed.

This work presents two novel methods to investigate in situ the carbon dioxide (CO2)-induced gelation of biopolymer-based solutions. The CO2-induced gelation is performed in a viewing cell at room temperature under CO2 pressure (20 to 60 bar), whereby calcium precursors are used as cross-linkers. The novel methods allow the in situ optical observation and evaluation of the gelation process via the change in turbidity due to dissolution of dispersed calcium carbonate (CaCO3) particles and in situ pH measurements. The combination of both methods enables the determination of the gelation direction, gelation rate, and the pH value in spatial and temporal resolution. The optical gelation front and pH front both propagate equally from top to bottom through the sample solutions, indicating a direct link between a decrease in the pH value and the dissolution of the CaCO3 particles. Close-to-vertical movement of both gelation front and pH front suggests almost one dimensional diffusion of CO2 from the contact surface (gel���CO2) to the bottom of the sample. The gelation rate increases with the increase in CO2 pressure. However, the increase in solution viscosity and the formation of a gel layer result in a strong decrease in the gelation rate due to a hindrance of CO2 diffusion. Released carbonate ions from CaCO3 dissolution directly influence the reaction equilibrium between CO2 and water and therefore the change in pH value of the solution. Increasing the CaCO3 concentrations up to the solubility results in lower gelation rates.

International audience; Dehulled yellow pea flour (48.2% starch, 23.4% proteins, d.b.), was processed by a twin-screw extruder at various moisture contents MC (18-35% w.b.), product temperature T (115-165 degrees C), and specific mechanical energy SME (50-1200 kJ/kg). Structural changes of extruded pea flour were determined at different scales by measurements of density (expansion), crystallinity (X-ray diffraction), gelatinisation enthalpy (DSC), starch solubility in water and protein solubility in SDS and DTE (SE-HPLC). Foam density dropped from 820 to 85 kg/m3 with increase in SME and T (R-2 >= 0.78). DSC and XRD results showed that starch was amorphous whatever extrusion conditions. Its solubility in water augmented up to 50%. Increasing temperature from 115 to 165 degrees C decreased proteins soluble in SDS from 95 to 35% (R-2 = 0.83) of total proteins, whereas the proteins soluble in DTE increased from 5 to 45% (R-2 = 0.75) of total proteins. These trends could be described by sigmoid models, which allowed determining onset temperatures for changes of protein solubility in the interval [125, 146 degrees C], whatever moisture content. The SME impact on protein solubility followed similar trends. These results suggest the creation of protein network by S-S bonds, implicating larger SDS-insoluble protein aggregates, as a result of increasing T and SME, accompanied by creation of covalent bonds other than S-S ones. CSLM images suggested that extruded pea flour had a composite morphology that changed from dispersed small protein aggregates to a bi-continuous matrix of large protein aggregates and amorphous starch. This morphology would govern the expansion of pea flour by extrusion.

Due to its renewability, availability and high cellulose content (≈45%), Alfa fibers (Stipa tenacissima) have been identified as a sustainable source for cellulose microfibers (CMF) and cellulose nanocrystals (CNC) production. Subjecting raw Alfa fibers to alkali, bleaching and sulfuric acid hydrolysis treatments allowed producing CMF and CNC with high yields. The fluorescence microscopy confirmed that CMF, with average diameter of 10 μm, were successfully obtained after bleaching treatments. TEM and AFM showed that the CNC exhibit needle-like shape with an average diameter and length of 5 ± 3 nm and 330 ± 30 nm, respectively, giving rise to an aspect ratio of about 66. XPS measurement confirmed the presence of sulfate groups on the surface of CNC with 2.04 sulfate groups per 100 anhydroglucose units, confirming the negatively charged surface of CNC, with zeta potential value of − 47.39 mV. XRD studies showed that CMF and CNC exhibit cellulose I structure with crystallinity index of 71% and 90%, respectively. FTIR and TGA analyses were used to identify the chemical composition and thermal stability changes during different chemical treatments, suggesting that all non-cellulosic compounds were removed after alkali and bleaching treatments. The obtained CNC were dispersed into three different biopolymer matrices, e.g. chitosan, alginate, and k-carrageenan, at various CNC loadings (1, 3, 5 and 8 wt%), to evaluate their ability to enhance the tensile properties of biopolymers and, at the same time, to produce new biopolymer-based nanocomposite films. It was found that the tensile properties of the as-produced nanocomposite films were largely improved with addition of CNC, resulting in mechanically strong and flexible ecofriendly nanocomposite films.

Structure and Dynamics of Polymer Composites and Gels: A Simulation Perspective. Edible Soft Matter – a SoftComp Topical Workshop

In face of growing environmental concerns, biodegradable and bio-sourced plastic nanocomposites are emerging as a new class of materials, especially for the food packaging sector. However, their use in food contact raises new issues in term of consumer safety. The aim of this study was to determine the impact of nanoclays on the apparent diffusion coefficient (D app ) of selected additives from biopolymers into fatty food simulants. For the most part, nanoclay addition has a non-conventional impact. To understand this, the following parameters were studied: (i) the exfoliation state of nanoclay platelets in the polymer matrix, (ii) the sorption of food simulant by the polymer matrix, and (iii) the crystallinity of the materials. At first glance, solvent uptake and crystallinity agree with the results of diffusivity, however these parameters cannot explain the extreme differences between D app values.

Aroma compounds are known to be efficient active agents for a broad range of applications (antimicrobial, anti-oxidant, insect repellent…) that are highly sought when aiming at extending shelf life of food or biological products. However, they are intrinsically odorant and volatile at ambient temperature, which restricts the processing routes used to introduce them in a polymeric matrix and can affect their mode of action and limit efficiency. Indeed, due to their high sensitivity toward temperature they can be lost or transformed during processing. Acting after being released in the headspace, their concentration has to be controlled to avoid any odorant contamination of the targeted products. Hence, the ability for an aroma compound to be retained in a polymeric matrix, and then released when submitted to a triggering effect, are the two main requirements that should be satisfied. The volatile nature of the aroma compound offer the possibility when introduce in the packaging to act by direct or indirect contact with the product and thus to be used in different ways; as a coating layer directly applied on the product surface, as a self-supported film or as coated paper when associated with a paper sheet, as well as an object that could be inserted in the package. As biopolymers such as proteins and polysaccharides are able to retain aroma compounds but also to favor their release by modification of their structure when the relative humidity (RH) and temperature change, they are relevant carriers of these specific aroma compounds. Examples of how active packaging systems with limonene, eugenol and carvacrol as active agents were designed and elaborated. These examples will be presented with a special focus on the processing conditions and the way to improve their aroma compound retention and the release control (biopolymer nature, cyclodextrin clay addition…). Avrami's equation has been used to model the transfer of aroma compound and to advantageously compare it taking into account the mechanism in relation to the biopolymer structural changes.

Background The oleaginous yeast Yarrowia lipolytica is an organism of choice for the tailored production of various compounds such as biofuels or biopolymers. When properly engineered, it is capable of producing medium-chain-length polyhydroxyalkanoate (mcl-PHA), a biobased and biodegradable polymer that can be used as bioplastics or biopolymers for environmental and biomedical applications. Results This study describes the bioproduction and the main properties of two different mcl-PHA polymers. We generated by metabolic engineering, strains of Y. lipolytica capable of accumulating more than 25% (g/g) of mcl-PHA polymers. Depending of the strain genetic background and the culture conditions, we produced (i) a mcl-PHA homopolymer of 3-hydroxydodecanoic acids, with a mass-average molar mass (Mw) of 316,000 g/mol, showing soft thermoplastic properties with potential applications in packaging and (ii) a mcl-PHA copolymer made of 3-hydroxyoctanoic (3HO), decanoic (3HD), dodecanoic (3HDD) and tetradecanoic (3TD) acids with a Mw of 128,000 g/mol, behaving like a thermoplastic elastomer with potential applications in biomedical material. Conclusion The ability to engineer Y. lipolytica to produce tailored PHAs together with the range of possible applications regarding their biophysical and mechanical properties opens new perspectives in the field of PHA bioproduction. Electronic supplementary material The online version of this article (10.1186/s12934-019-1140-y) contains supplementary material, which is available to authorized users.

Understanding how polymerases catalyze the synthesis of biopolymers is a timely and important issue in generating controlled structures with well-defined properties. With this objective in mind, here we describe the 2.8 angstrom crystal structure of a truncated version of alternansucrase (ASR) from L. citreum NRRL B-1355. Indeed, ASR is a striking example of alpha-transglucosylase among GH70 glucansucrases, capable of catalyzing high and low molar mass alternan, an alpha-glucan comprising alternating alpha-1,3 and alpha-1,6 linkages in its linear chain. The 3D structure sheds light on the various features involved in enzyme stability. Moreover, docking studies and biochemical characterizations of 17 single mutants and two double mutants enable the key determinants of alpha-1,6 or alpha-1,3 linkage specificity to be located and establish the structural basis of alternance. ASR displays two different acceptor subsites in the prolongation of its subsites -1 and +1. The first one is defined by Trp675, a residue of subsite +2, and orients acceptor binding exclusively toward alpha-1,6 linkage synthesis. The second binding site comprises Asp772 and Trp543, two residues defining the +2' and +3' subsites, respectively, which are critical for alpha-1,3 linkage formation. It is proposed that the interplay between these two acceptor sites controls alternance. These results add to the toolbox of enzymes for the production of tailor-made polysaccharides with controlled structures.

International audience; Owing to their specific pyrylium nucleus (C-ring), anthocyanins express a much richerchemical reactivity than the other flavonoid classes. For instance, anthocyanins are weak diacids, hard and soft electrophiles, nucleophiles, prone to developing -stacking interactions, and bind hard metal ions. They also display the usual chemical properties of polyphenols, such as electron donation and affinity for proteins. In this review, these properties are revisited through a variety of examples and discussed in relation to their consequences in food and in nutrition with an emphasis on the transformations occurring upon storage or thermal treatment and on the catabolism of anthocyanins in humans, which is of critical importance for interpreting their effects on health.

Chitosan is a natural polymer obtained by deacetylation of chitin. This polysaccharide is well known for its exceptional biological properties: it is biocompatible and bio absorbable. Chitosan fibers can be used in surgery.The objective of this thesis is to study the physicochemical phenomena involved, to develop a process model, to optimize the filtering process in the laboratory.After a review of the literature in the first chapter, the experimental techniques for obtaining, purifying and characterizing chitosan are described in the second chapter. A study of the structure of the chitosan obtained is presented. This is one of the original results of this work.The principle of the coagulation method in solution, it is essential to determine in what condition it, and what is the determining parameter. Previous studies have shown that this is the diffusion coefficient of soda in the medium. One effect, measurements were made, in different geometries. This study constitutes the work presented in Chapter Three.In chapter four is presented a technique consisting in following by means of a microscope the advance of the coagulation front. This technique makes it possible to determine the diffusion coefficient.The last chapter consisted of developing fibers using a small scale plant existing in laboratory (IMP Lyon 1). The final element of this work consists of modelling the process, calculating the inside and outside diameters of the fibers obtained and comparing the result of the modelling with the experimental results; Le chitosane est un polymère naturel obtenu par deacétylation de la chitine. Ce polysaccharide est bien connu pour ses propriétés biologiques exceptionnelles : il est biocompatible et biorésorbable. Les fibres de chitosane peuvent être utilisées en chirurgie. L'objectif de cette thèse est d'étudier les phénomènes physico-chimiques mis en jeu, de développer un modèle du procédé, afin d'optimiser le procédé de filage mis au point au laboratoire.Après une revue de la littérature dans le premier chapitre, les techniques expérimentales d'obtention, de purification, et de caractérisation du chitosane sont décrits dans le deuxième chapitre. Une étude de la structure du chitosane obtenu est présentée. C'est l'un des résultats originaux de ce travail.Le principe du procédé étant par coagulation en solution, il est essentiel de déterminer dans quelle condition celle-ci s'effectue, et quel est le paramètre déterminant. Les études précédentes ont montré que celui-ci est le coefficient de diffusion de la soude dans le milieu. A cet effet, des mesures ont été effectuées, dans des géométries différentes. Cette étude constitue le travail présenté dans le chapitre trois.Dans le chapitre quatre est présentée une technique consistant à suivre au moyen d'un microscope l'avancée du front de coagulation. Cette technique a permis de déterminer précisément le coefficient de diffusion.Le dernier chapitre a consisté à élaborer des fibres au moyen d'un banc que possède le laboratoire (IMP Lyon 1). L'étape ultime de ce travail a été de modéliser le procédé, de prévoir les diamètres intérieur et extérieur des fibres obtenues, et de comparer le résultat de la modélisation aux résultats expérimentaux

Chitosan is a natural polymer obtained by deacetylation of chitin. This polysaccharide is well known for its exceptional biological properties: it is biocompatible and bio absorbable. Chitosan fibers can be used in surgery.The objective of this thesis is to study the physicochemical phenomena involved, to develop a process model, to optimize the filtering process in the laboratory.After a review of the literature in the first chapter, the experimental techniques for obtaining, purifying and characterizing chitosan are described in the second chapter. A study of the structure of the chitosan obtained is presented. This is one of the original results of this work.The principle of the coagulation method in solution, it is essential to determine in what condition it, and what is the determining parameter. Previous studies have shown that this is the diffusion coefficient of soda in the medium. One effect, measurements were made, in different geometries. This study constitutes the work presented in Chapter Three.In chapter four is presented a technique consisting in following by means of a microscope the advance of the coagulation front. This technique makes it possible to determine the diffusion coefficient.The last chapter consisted of developing fibers using a small scale plant existing in laboratory (IMP Lyon 1). The final element of this work consists of modelling the process, calculating the inside and outside diameters of the fibers obtained and comparing the result of the modelling with the experimental results, Le chitosane est un polymère naturel obtenu par deacétylation de la chitine. Ce polysaccharide est bien connu pour ses propriétés biologiques exceptionnelles : il est biocompatible et biorésorbable. Les fibres de chitosane peuvent être utilisées en chirurgie. L'objectif de cette thèse est d'étudier les phénomènes physico-chimiques mis en jeu, de développer un modèle du procédé, afin d'optimiser le procédé de filage mis au point au laboratoire.Après une revue de la littérature dans le premier chapitre, les techniques expérimentales d'obtention, de purification, et de caractérisation du chitosane sont décrits dans le deuxième chapitre. Une étude de la structure du chitosane obtenu est présentée. C'est l'un des résultats originaux de ce travail.Le principe du procédé étant par coagulation en solution, il est essentiel de déterminer dans quelle condition celle-ci s'effectue, et quel est le paramètre déterminant. Les études précédentes ont montré que celui-ci est le coefficient de diffusion de la soude dans le milieu. A cet effet, des mesures ont été effectuées, dans des géométries différentes. Cette étude constitue le travail présenté dans le chapitre trois.Dans le chapitre quatre est présentée une technique consistant à suivre au moyen d'un microscope l'avancée du front de coagulation. Cette technique a permis de déterminer précisément le coefficient de diffusion.Le dernier chapitre a consisté à élaborer des fibres au moyen d'un banc que possède le laboratoire (IMP Lyon 1). L'étape ultime de ce travail a été de modéliser le procédé, de prévoir les diamètres intérieur et extérieur des fibres obtenues, et de comparer le résultat de la modélisation aux résultats expérimentaux

Agricultural resources give us food but also potential sources of feedstocks for the chemical industry. As demand from the growing human population rises, the food industry and the chemical industry face similar problems of scaling operations while sourcing the largest possible amount of at least reasonable-quality raw materials. Food is composed of complex structures formed from molecular assemblies ( e.g. particles, fibres, crystals) whose properties depend in part on the molecular species present. In this context, investigations are needed to better understand raw material structure and structure transformation mechanisms in order to improve manufacturing processes and the properties of the final product ( e.g. food), which means dedicated methodologies need to be developed. This review presents case studies illustrating advanced technologies designed for characterizing biopolymers, supramolecular complexes, cell membranes, enzymatic degradation of food matrices and biopolymers, flavor release dynamics during eating, cerebral multisensory integration of food and eating behavior.

Amylose, a mostly linear homopolymer of α(1,4)-linked glucosyl units extracted from native starch, has the remarkable property to form "V-amylose" crystalline complexes with a variety of small organic molecules. We have tested the ability of 120 compounds to induce the crystallization of amylose from dilute aqueous solutions. The morphology and structure of the resulting lamellar crystals were characterized by transmission electron microscopy as well as electron and X ray diffraction. The data revealed that the structures of the complexes could be classified into 10 families, 5 of which were described for the first time. In addition, 13C solid-state nuclear magnetic resonance spectra clearly showed that the helicity of V-amylose was correlated with the resonance of carbon C1 that was shifted downfield with increasing number of glucosyl units per turn. Tentative geometrical models were proposed for all allomorphs and the structure of V1-butanol was analyzed in more details by combining conformational and packing energy calculations with classical crystalline polymer structure refinement. All allomorphs contained 6-, 7- or 8-fold amylose single helices and the guest molecules could be located inside these helices, in-between, or both. Each allomorph could be obtained with different complexing agents and the helical conformation was found to depend on the size of the complexing agent. In addition, a given ligand could induce the formation of several allomorphs, suggesting that the polymorphism of V-amylose crystals is a more general characteristic than what was previously reported. The propensity for polymorphism is not only related to the nature of the complexing agent but also to the crystallization conditions. The degree of polymerization of amylose, its concentration and that of the complexing agent, the temperature of mixing and crystallization, and the solvent composition have a significant impact on the formation and crystal structure of V-amylose. In addition, crystalline complexes prepared with ibuprofen were used as a model to evaluate the potential of V-amylose as a delivery system of bioactive molecules. Different fractions of ibuprofen, likely correlated with the different locations of the guest in the crystal, were selectively released by varying the pH of the dissolution medium. Since the release mainly occurred at high pH, these inclusion complexes appear to be potentially interesting for intestinal targeting and would thus improve the therapeutic effect of ibuprofen., L'amylose est un homopolymère quasi-linéaire d'unités glucosyles liées en α(1,4) qui, extrait de l'amidon natif, possède la propriété remarquable de former des complexes cristallins avec une grande variété de petites molécules organiques. Ces complexes sont regroupés sous le terme générique d'amylose V. Nous avons testé la capacité de 120 composés à induire la cristallisation de l'amylose à partir de solutions aqueuses diluées. La morphologie et la structure des cristaux lamellaires formés ont été caractérisés par microscopie électronique en transmission ainsi que par diffraction des électrons et des rayons X. Les données révèlent que les structures de ces complexes peuvent être classées en 10 familles dont 5 sont décrites pour la première fois. Des spectres de résonnance magnétique nucléaire du solide du 13C montrent clairement que l'hélicité de l'amylose V est corrélée à la résonnance du carbone C1 qui se déplace vers les champs faibles lorsque le nombre d'unités glucosyles par tour augmente. Des modèles géométriques préliminaires ont été proposés pour tous les allomorphes, la structure de cristaux de V1-butanol ayant été analysée en détail en combinant des calculs de conformation et d'énergie d'empilement avec un affinement de structure de polymère cristallin classique. Tous les allomorphes contiennent des simples hélices d'amylose d'ordre 6, 7 ou 8 et les molécules invitées peuvent être localisées dans ces hélices, entre elles ou les deux. Chaque type d'allomorphe peut être obtenu avec différents complexants et la conformation de l'hélice d'amylose dépend de la taille du complexant. De plus, un ligand donné est susceptible d'induire la formation de plusieurs allomorphes. Le polymorphisme cristallin de l'amylose serait donc une caractéristique plus générale que ce qui avait été rapporté auparavant. La propension au polymorphisme dépend non seulement de la nature du complexant mais aussi des conditions de cristallisation. Le degré de polymérisation de l'amylose, sa concentration et celle du complexant, la température de mélange ou de cristallisation et la composition du solvant ont un impact significatif sur la formation de cristaux et la structure de l'amylose V. Par ailleurs, nous avons utilisé des complexes avec l'ibuprofène comme modèle afin d'évaluer le potentiel de l'amylose V comme système de délivrance de principes actifs. Différentes fractions d'ibuprofène, probablement corrélées aux positions possibles de la molécule dans le cristal, sont sélectivement relarguées en variant le pH du milieu de dissolution. Puisque le relargage intervient principalement à pH élevé, ces complexes d'inclusion sont donc potentiellement intéressants pour cibler une libération intestinale et pourraient donc améliorer l'effet thérapeutiques de l'ibuprofène.