Arylindaan diolen als veilige en duurzame polymeeradditieven

Plastics are indispensable in modern society, supporting innovation in packaging, transportation, electronics, healthcare, and beyond. Their durability and performance, however, rely on the use of additives such as antioxidants, which protect polymer chains from oxidative degradation, and plasticizers, which improve flexibility and processability. Conventional additives remain almost entirely fossil-derived and include synthetic phenolic antioxidants (SPAs) such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA), as well as common phthalate plasticizers. However, these substances face increasing scrutiny due to their tendency to leach, their potential toxicity, and environmental persistence. The challenge for the next generation of polymer additives is therefore not only to reduce dependence on fossil resources but also to integrate low-hazard profiles and high functionality by design. This vision is captured in the European Union's Safe and Sustainable by Design (SSbD) framework, which promotes the integration of performance, safety, and sustainability in early-stage molecular development. Lignin, a major component of lignocellulose, offers a renewable and structurally diverse source of phenolic building blocks. Its depolymerization can provide reactive monomers that serve as precursors for value-added molecules. Importantly, the o-methoxy substitution patterns characteristic of many lignin-derived phenols have been shown to reduce estrogenic activity, further supporting their promise as safer bio-based alternatives. One such example is isoeugenol (IE), which can undergo acid-catalyzed dimerization to form diisoeugenol (DiE), a representative arylindane diol. These molecules feature two aromatic rings connected by a rigid indane backbone with two phenolic hydroxyl groups, providing both conformational stability and radical-scavenging reactivity. More broadly, arylindane diols have been linked to antioxidant, anti-inflammatory, and antiplatelet activity. In this dissertation, a selective and sustainable route to diisoeugenol (DiE) was established using a recyclable H-USY Brønsted acid catalyst, while Density Functional Theory (DFT) studies confirmed the formation of the two main diastereoisomers (α and γ). This zeolite-catalyzed approach adheres to several Green Chemistry principles, including catalysis, atom economy, waste prevention, and the avoidance of derivatization steps. Building on this foundation, the molecular scope of arylindane diols was expanded to a broader library of compounds. This included diisoallylsyringol (DiAS), a novel analogue distinguished by additional o-methoxy substituents, as well as derivatives of ferulic acid (FA) and sinapic acid (SA): diferulic acid (DFA), disinapic acid (DSA), and a homologous series of dialkyl ferulates—dimethyl ferulate (DMF), diethyl ferulate (DEF), dibutyl ferulate (DBF), and dioctyl ferulate (DOF). The latter required prior esterification of FA before dimerization. Collectively, these compounds provide a tunable set of steric, electronic, and polarity features for systematic evaluation of structure-function relationships. The antioxidant, biological, and application performance were evaluated to explore their potential as renewable polymer additives. Radical scavenging assays (ABTS and DPPH) showed strong activity for all arylindane diols, surpassing fossil-derived benchmark antioxidants such as BHT, BHA, and Irganox® 1010 (Irg1010). Biological testing confirmed a favorable safety profile. In the ERα CALUX assay, DiE showed an EC50 of 5.9 × 10-6 M, markedly lower than the well-known endocrine disruptor bisphenol A (BPA, 6.4 × 10-7 M) and 17β-estradiol (E2, 7.9 × 10--12 M). More importantly, no detectable EA was observed for DiAS, DFA, DSA, DMF, or DEF up to 10-3 M. Cytotoxicity, as measured by XTT and LDH assays, was generally low, with DFA and DSA in particular showing negligible effects within relevant concentration ranges. These results demonstrate that o-methoxy groups, particularly when combined with bulky or polar substituents, can fully suppress measurable EA in arylindane diols, strengthening structure-toxicity relationships in this compound class and supporting safe-by-design development of renewable antioxidants. Application performance was tested in polypropylene (PP) and polylactic acid (PLA). In PP, α-DiE and DiAS increased the oxidation onset temperature (OOT) by 21 °C and 29 °C, respectively, outperforming commercial antioxidants. In PLA, dialkyl ferulate-derived diols such as DOF not only stabilized the polymer against thermal oxidation but also acted as plasticizers, lowering the glass transition temperature (Tg) from 62.1 °C to 53.1 °C. This dual antioxidant-plasticizing effect is rarely achieved with single additives, positioning arylindane diols as multifunctional candidates for advanced materials. In summary, this research introduces a platform of renewable, multifunctional arylindane diols that combine high antioxidant performance with low endocrine and cytotoxic activity, derived from structurally diverse, bio-based phenolic monomers. Their synthesis under mild catalytic conditions, paired with demonstrated performance in industrially relevant polymer matrices, highlights their potential as safer alternatives to conventional phenolic additives. Importantly, this work aligns with the SSbD framework by integrating renewable sourcing, early-stage hazard screening, and functional evaluation into the molecular design process. As the chemical industry moves toward circularity and safety, such compounds represent a step forward in bridging the gap between bio-based feedstocks and high-performance, low-toxicity materials.