Synthese und Entwicklung von bio-basierten UV-härtenden Monomeren und hochverzweigten Polymeren aus Itaconsäure

In this work, acrylic acid-based HBP and various monomers and polymers from itaconic acid have been synthesized and evaluated to gain a deeper understanding about the structure-properties relationship of UV-curing hyperbranched polymers. The focus was placed on the use of itaconic acid as it has the potential to be a bio-based alternative to acrylic acid for a range of UV-curing applications such as additive manufacturing, coatings or printing inks. Six acrylated HBP were synthesized and evaluated to determine the impact of each building block on the final properties. A novel simple synthesis pathway was developed that did not require the use of activated reagents leading to highly substituted materials while avoiding all gelation risk. The material showed higher reactivity towards UV-curing and higher mechanical and thermal properties than materials previously described. Novel building blocks from itaconic acid were developed using a simple and scalable process. Eight monoesters of itaconic acid were synthesized using simple and more complex cyclic alcohols. These monomers were reacted with a vegetable oil and the characterization of the resulting material showed that cyclohexyl itaconate was the most promising candidate. Hyperbranched polymers from itaconic acid were synthesized through different strategies. As simple esterification reactions lead to undesired side-reaction when the difunctional itaconic acid is used, several alternative pathways were investigated and are described. The most successful strategy involved the reaction of itaconic anhydride with a (branched) core followed by an end-capping reaction with an epoxide. Applying this strategy, 13 hydroxyalkyl terminated HBP_It were developed using a variety of core, generations and end groups. These promising materials exhibited good reactivity and properties and are good candidates to be used as UV-curable material or additive tougheners. Finally, novel reactive diluents from itaconic acid were synthesized, the first of their kind due to the challenging reactivity of itaconic and the lower intrinsic reactivity towards UV-curing. These monomers were found to greatly improve the viscosity, the reactivity, and the thermal and mechanical properties when mixed with UV-curing resins derived from itaconic acid.In dieser Arbeit wurden hochverzweigte Polyester auf Acrylsäure-Basis und UV-härtende Monomere and Polymere aus Itaconsäure synthetisiert und evaluiert, um ein besseres Verständnis der Struktur-Eigenschafts-Beziehungen dieser Art der Polymere zu erhalten. Der Schwerpunkt wurde auf die Verwendung von Itaconsäure gelegt, einer bio-basierten Alternative zu Acrylsäure im Bereich der UV-härtenden Anwendungen, wie 3D-Druck, Beschichtungen oder Druckfarben. Sechs Acrylsäure-basierte HBP wurden synthetisiert und evaluiert, um den Einfluss der Bausteine auf die Eigenschaften auszuwerten. Eine neuartige and einfache Synthese wurde entwickelt, bei der keine aktivierten Reagenzien verwendet werden musste. Diese Methode erlaubte die Synthese von hochsubstituierten Materialen ohne das Risiko einer vorzeitigen Vernetzung. Die Materialen zeigten eine höhere Reaktivität gegenüber UV-Härtung und höhere mechanische und thermische Eigenschaften als bekannte Materialen. Neue Bausteine aus Itaconsäure wurden in einem einfachen und skalierbaren Verfahren entwickelt. Acht Monoester der Itaconsäure wurden mit einfachen und komplexeren zyklischen Alkoholen synthetisiert. Diese Monomere wurden mit Pflanzenöl reagiert und die Charakterisierung der Materialien zeigte, dass Cyclohexylitaconat die besten Eigenschaften aufwies. Hochverzweigte Polymere ausgehend von Itaconsäure wurden durch verschiedene Strategien synthetisiert, Da einfache Veresterungsreaktionen zu unerwünschten Nebenprodukten führen, wenn die difunktionale Itaconsäure verwendet wird, wurden mehrere alternative Synthesestrategien entwickelt und beschrieben. Die vielversprechendsten Ergebnisse wurden durch die Reaktion von Itaconsäureanhydrid mit dem (verzweigten) Kern gefolgt von einer Reaktion mit einem Epoxid erhalten. Mit dieser Methode wurden 13 hydroxyalkyl-terminierte HBP_It mit verschiedenen Kernen, Generationen und Endgruppen synthetisiert. Die erhaltenen Materialen zeigten gute Reaktivitäten und Eigenschaften und eignen sich für den Einsatz als Harze oder Additive in UV-härtenden Materialien. Darüber hinaus wurden erstmalig neuartige Reaktivverdünner aus Itaconsäure synthetisiert; ein Unterfangen, was durch die geringere Reaktivität der Itaconsäure sehr herausfordernd ist. Diese Monomere verbesserten die Viskosität, die Reaktivität und die thermischen und mechanischen Eigenschaften, wenn sie mit einem UV-härtenden Harzen auf Itaconsäure-Basis gemischt und gehärtet wurden

1,3-Propanediol and its application in bio-based polyesters for resin applications

Polyester resins are important raw materials for a myriad of applications especially in the field of coatings and radical curing polymers, such as wood and powder coatings, molding compounds, and UV-curing applications. In addition, polyols derived from polyester resins are precursors for the synthesis of polyurethanes and polycarbonates. Besides dicarboxylic acid, diols are used as monomers in these polyesters. To date most of the diols utilized are derived from petrochemical feedstock. To increase the bio-based content of polyester resins, novel diols derived from renewable resources are of special interest. In this respect, 1,3-propanediol has drawn considerable attention over the last years. It is accessible via microbial fermentation of glucose from starch at a competitive price in sufficient amounts. Therefore, 1,3-propanediol could be a valuable alternative to petrochemical diols, such as 1,6-hexanediol and neopentylglycol, which are currently used as diols in most resin applications. This article gives a brief overview over the utilization of 1,3-propanediol in high molecular weight polyesters for plastic application followed by a more detailed discussion of the most relevant work in the field of polyester resins derived from 1,3-propanediol

Optimized synthesis of highly reactive UV-curable hyperbranched polyester acrylates

Highly reactive radical polyester acrylates are widely used as UV-curing binder resins for printing inks, coatings, and materials for additive manufacturing. Especially for the latter, polyesters with low viscosities are of high interest, as they allow for UV-curing materials with reduced amounts of reactive diluents to adjust the viscosity. One possibility to obtain polyester acrylates with low viscosities is the synthesis of hyperbranched structures, as the interactions of the polymer chains are reduced in comparison to their linear counterparts. In this study, an optimized synthetic protocol is described to obtain a set of highly branched polyester acrylates with a high degree of acrylation, without the use of activated reagents like anhydrides or acid chlorides that are usually employed to synthesize these products. Different cores and number of pseudo-generations of 2,2-bis(hydroxymethyl)propionic (bisMPA) are utilized to study the structure–property relationship of this class of polyesters. Comprehensive characterization of the synthesized resins and cured materials revealed high reactivities and good mechanical properties compared to similar materials reported in the literature. The design of the structure significantly influences the properties, allowing for the synthesis of specific resins with a wide range of potential applications

Selective synthesis of monoesters of itaconic acid with broad substrate scope: Biobased alternatives to acrylic acid?

Over the last few years, there has been an increasing interest to identify biobased alternatives to acrylic acid in UV-curing materials. In this respect, itaconic acid has drawn considerable attention, due to its structural similarity. However, the second acid group in the molecule limits its use in many applications, as undesired side reactions can occur. One solution is the use of monoesters of itaconic acid to mimic the properties of acrylic acid. However, to date, no general applicable and straightforward synthetic protocol has been reported. Herein, the synthesis of a variety of monoesters of itaconic acid is presented. The methodology tolerates a broad substrate scope, is highly efficient, and does not suffer from tedious purification steps; therefore it can be applied on large scale. In the next step, the monoesters were reacted with epoxidized soybean oil to produce biobased UV-curing oligomers. The influence of the different monoesters on the properties of the functionalized vegetable oils, such as viscosity as well as the reactivity toward UV-light induced radical cross-linking, was studied. In addition, these findings were compared with those of acrylated soybean oil. Despite the lower rate of polymerization of the itaconic acid-based oligomers, the double bond conversion was higher in some cases. In addition, the viscosity was found to be lower in comparison to that of the acrylic acid-derived compound, making these novel monoesters promising alternatives to the petrochemical-based acrylic acid

First Example of Unsaturated Poly(Ester Amide)s Derived From Itaconic Acid and Their Application as Bio-Based UV-Curing Polymers

Recently, itaconic acid has drawn considerable attention as a novel radical-curing building block for polyester resins. These bio-based materials have been used in thermal, as well as ultra violet (UV) curing applications, such as printing inks or coatings. Poly(ester amide)s from itaconic acid could be very interesting, as the amide group could alter the properties of the resins as well as cured materials. However, standard polycondensation reactions with diamines are not possible with itaconic acid as the amines preferably react via an aza-Michael addition at the α,β-unsaturated double bond. Therefore, alternative and more elaborate synthetic strategies have to be developed. Herein, we present two different synthetic strategies to poly(ester amide)s from itaconic acid that circumvent the addition reaction of the amines. This is in both cases done by a pre-reaction to form stable amide building blocks that are then reacted with itaconic acid or polyesters derived thereof. The structural composition and the properties of the resin are characterized, and the UV-curing reactivity is examined. All properties are compared to corresponding polyesters from itaconic acid

Electrochemical Coupling of Biomass‐Derived Acids: New C8 Platforms for Renewable Polymers and Fuels

Electrolysis of biomass-derived carbonyl compounds is an alternative to condensation chemistry for supplying products with chain length >C6 for biofuels and renewable materials production. Kolbe coupling of biomass-derived levulinic acid is used to obtain 2,7-octanedione, a new platform molecule only two low process-intensity steps removed from raw biomass. Hydrogenation to 2,7-octanediol provides a chiral secondary diol largely unknown to polymer chemistry, whereas intramolecular aldol condensation followed by hydrogenation yields branched cycloalkanes suitable for use as high-octane, cellulosic gasoline. Analogous electrolysis of an itaconic acid-derived methylsuccinic monoester yields a chiral 2,5-dimethyladipic acid diester, another underutilized monomer owing to lack of availability

Understanding additive degradation pathways and formation of Non-Intentionally Added Substances

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