From Forest to Future: Synthesis of Sustainable High Molecular Weight Polyamides Using and Investigating the AROP of ß-Pinene Lactam.

Polyamides (PA) are among the most essential and versatile polymers due to their outstanding characteristics, for example, high chemical resistance and temperature stability. Furthermore, nature-derived monomers can introduce hard-to-synthesize structures into the PAs for unique polymer properties. Pinene, as one of the most abundant terpenes in nature and its presumable stability-giving bicyclic structure, is therefore highly promising. This work presents simple anionic ring-opening polymerizations of ß-pinene lactam (AROP) in-bulk and in solution. PAs with high molecular weights, suitable for further processing, are produced. Their good mechanical, thermal (Td s up to 440 °C), and transparent appearance render them promising high-performance biomaterials. In the following, the suitability of different initiators is discussed. Thereby, it is found that NaH is the most successful for in-bulk polymerization, with a degree of polymerization (DP) of about 322. For solution-AROP, iPrMgCl·LiCl is successfully used for the first time, achieving DPs up to about 163. The obtained PAs are also hot-pressed, and the dynamic mechanical properties are analyzed.

(+)-Limonene-Lactam: Synthesis of a Sustainable Monomer for Ring-Opening Polymerization to Novel, Biobased Polyamides.

In this work, the synthesis of limonene lactam starting from limonene epoxide and its subsequent ring-opening polymerization (ROP) to novel polyamides is presented. Sustainable, biobased materials are gaining interest as replacements of conventional, petroleum-based materials, and even more important, as high-performance materials for new applications. Terpenes-structurally advanced biobased compounds-are therefore of great interest. In this research, limonene lactam, a novel biobased monomer for preparing sustainable polyamides via ROP, can be synthesized. Limonene lactam possesses an isopropylene and a methyl side group, thus stereocenters posing special challenges and requirements for synthesis, analysis and polymerization. However, these difficult-to-synthesize structural elements can generate novel polymers with unique properties, e.g., functionalizability. In this work, a sustainable monomer synthesis is established, and simplified to industrial needs. For the sterically demanding in-bulk ROP to limonene polyamides, various initiators and conditions are tested. Polyamides with more than 100 monomer units are successfully synthesized and confirmed via nuclear magnetic resonance (NMR) spectroscopy and gel permeations chromatography (GPC). Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) are used to analyze its thermal properties. In summary, a sustainable monomer synthesis is established, and promising polyamides with intact double bond and interesting thermal properties are achieved.

[OSSO]-Type Chromium(III) Complexes for the Reaction of CO2 with Epoxides.

In this work, four new mononuclear Cr(III) complexes (2-5) bearing bis-thioether-diphenolate, [OSSO]-type ligands, were synthesized and characterized. These complexes in combination with bis(triphenylphosphine)iminium chloride (PPNCl) promoted the coupling of CO2 with epoxides. Depending on the type of substrate and the conditions, the reaction results in the selective formation of either polycarbonate or cyclic carbonate. For example, the reactions in the presence of complex 2 led to the exclusive formation of poly(cyclohexene carbonate, PCHC) from cyclohexene oxide (CHO) (TOF up to 39 h-1 , at T=45-100 °C, time=24 h, pCO2 =20 bar, epoxide/2 (mol/mol)=1000, and PPNCl/2=0.5-2.0 mol %). Under the same conditions and PPNCl/2=0.5-5.0 mol %, the reactions of CO2 with styrene oxide (SO), epichlorohydrin (ECH), 1,2 epoxydodecane (EDD), and allyl glycidyl ether (AGE) have shown selective conversion to the corresponding cyclic carbonates (TOF up to 41 h-1 ).

ß-Pinene-Derived Polyesteramides and Their Blends: Advances in Their Upscaling, Processing, and Characterization.

Terpene-based polyesteramides (PEAs) are sustainable and have a variety of favorable properties, making them suitable for a wide range of applications and for contribution to a much more sustainable polymer industry. This work focuses on the synthesis of the lactam from ß-pinene and its copolymerization with ε-caprolactone. An important step in synthesizing ß-pinene lactam is the oxidation of ß-pinene to nopinone. To make the established oxidative cleavage more sustainable and efficient, the required amounts of Al2 O3 and KMnO4 are significantly reduced by using H2 SO4 as a catalyst. For the Beckmann rearrangement various catalysts and co-reagents are screened. Among these, the reaction with tosyl chloride is found the most favorable. Subsequently, the chain lengths of the ß-pinene-based PEAs are remarkably increased from 6000 g mol-1 to more than 25 100 g mol-1 by fine-tuning reaction time, temperature, and decreasing catalyst and initiator concentrations. Also, different catalysts for polymerization are tested. The resulting material shows melting temperatures of ≈55 °C and decomposition temperatures of 354 °C or higher. Processing via melt pressing or casting turned out to be quite difficult due to the polymer's brittleness. Furthermore, regarding biomedical applications, blends of PEA with polyethylene glycol were successfully prepared, yielding a more hydrophilic material.

Sustainable Myrcene-Based Elastomers via a Convenient Anionic Polymerization.

Soluble heterocomplexes consisting of sodium hydride in combination with trialkylaluminum derivatives have been used as anionic initiating systems at 100 °C in toluene for convenient homo-, co- and ter-polymerization of myrcene with styrene and isoprene. In this way it has been possible to obtain elastomeric materials in a wide range of compositions with interesting thermal profiles and different polymeric architectures by simply modulating the alimentation feed and the (monomers)/(initiator systems) ratio. Especially, a complete study of the myrcene-styrene copolymers (PMS) was carried out, highlighting their tapered microstructures with high molecular weights (up to 159.8 KDa) and a single glass transition temperature. For PMS copolymer reactivity ratios, rmyr = 0.12 ± 0.003 and rsty = 3.18 ± 0.65 and rmyr = 0.10 ± 0.004 and rsty = 3.32 ± 0.68 were determined according to the Kelen-Tudos (KT) and extended Kelen-Tudos (exKT) methods, respectively. Finally, this study showed an easy accessible approach for the production of various elastomers by anionic copolymerization of renewable terpenes, such as myrcene, with commodities.