Periodic Reporting for period 1 - SUPREME (Sustainable Polyesters and Renewable Terpenoid Monomers)
Okres sprawozdawczy: 2019-07-01 do 2021-06-30
The global plastics production reached 335 million tons in 2016, absorbing about 6% of the fossil feedstock extraction. Nowadays, due to the depletion of the oil reserves and to the raising environmental concerns related with these raw materials and the end-of-life disposal (cf., “plastic soup”), many countries are now increasingly adopting strict legislation on the use of certain monomers and plastics to mitigate these effects. Therefore, the demand for more sustainable and renewable monomers and polymers is gaining huge momentum.
In this context, aliphatic polyesters (APEs) represent one of the most appealing types of plastic materials, because of their general biocompatibility and facile hydrolytic degradation. The ring opening polymerization (ROP) of cyclic esters and lactides (usually promoted by metal complexes) is one of the most effective ways toward APE production. This polymerization technique allows for excellent control over the molecular weights of the final polymer, and typically with narrow molecular weight distributions. Unfortunately, the reaction is often limited to six- and seven-membered cyclic monomers, reducing significantly the range of mechanical, thermal and post-synthetic properties of the APEs, and consequently a wider application of APEs in consumer products. The physical properties of poly(lactic acid) (PLA), a well-known commercial APE, can to some extent be modulated by copolymerization with other cyclic esters, and typically copolymerization with petrochemicals-derived ε-caprolactone (CL) is carried out to achieve this goal. However, current polymerization technologies greatly suffer from the availability of more functional monomers that can widen the scope (in particular the thermal resistance, cf. glass transitions (Tg) values) of APEs in current and new materials with an improved sustainability footprint. Therefore, the use of accessible, bio-sourced monomers for APE synthesis is highly attractive since these monomers are generally renewable, cheap and offer the structural and molecular diversity not present in the conventional monomers to explore novel and unexplored properties for APEs. A proper choice of the biobased monomer will greatly facilitate the design of new APEs with improved or unknown electronic, thermal and mechanical properties interesting from both an academic and industrial perspective.
The primary aim of the SUPREME project is the creation of new polyester formulations based on renewable and accessible terpene monomers to answer to the growing need for future generations of more functional and sustainable materials. The results of the action will have a strong impact on the society, giving the opportunity to assess circular economy concepts in industrial sector with high environmental impact, such as that of biopolymers. Therefore, this project is closely aligned with the H2020 priorities, especially within the societal challenge 5: Climate action, environment, resource efficiency and raw materials.
The specific objectives of the SUPREME project are the following:
SO1. ROP of 1,2-campholide (CAM) to afford the new APE poly(campholide), PCAM
SO2. Synthesis of new APEs through ROCOP of β-elemene monoxide (BEM) and camphoric
anhydride (CA) to produce various polyesters with tunable functionality and rigidity
SO3. Post-modification of a functional APE obtained under SO2, and the study of the thermal, chemical and mechanical properties
In this context, aliphatic polyesters (APEs) represent one of the most appealing types of plastic materials, because of their general biocompatibility and facile hydrolytic degradation. The ring opening polymerization (ROP) of cyclic esters and lactides (usually promoted by metal complexes) is one of the most effective ways toward APE production. This polymerization technique allows for excellent control over the molecular weights of the final polymer, and typically with narrow molecular weight distributions. Unfortunately, the reaction is often limited to six- and seven-membered cyclic monomers, reducing significantly the range of mechanical, thermal and post-synthetic properties of the APEs, and consequently a wider application of APEs in consumer products. The physical properties of poly(lactic acid) (PLA), a well-known commercial APE, can to some extent be modulated by copolymerization with other cyclic esters, and typically copolymerization with petrochemicals-derived ε-caprolactone (CL) is carried out to achieve this goal. However, current polymerization technologies greatly suffer from the availability of more functional monomers that can widen the scope (in particular the thermal resistance, cf. glass transitions (Tg) values) of APEs in current and new materials with an improved sustainability footprint. Therefore, the use of accessible, bio-sourced monomers for APE synthesis is highly attractive since these monomers are generally renewable, cheap and offer the structural and molecular diversity not present in the conventional monomers to explore novel and unexplored properties for APEs. A proper choice of the biobased monomer will greatly facilitate the design of new APEs with improved or unknown electronic, thermal and mechanical properties interesting from both an academic and industrial perspective.
The primary aim of the SUPREME project is the creation of new polyester formulations based on renewable and accessible terpene monomers to answer to the growing need for future generations of more functional and sustainable materials. The results of the action will have a strong impact on the society, giving the opportunity to assess circular economy concepts in industrial sector with high environmental impact, such as that of biopolymers. Therefore, this project is closely aligned with the H2020 priorities, especially within the societal challenge 5: Climate action, environment, resource efficiency and raw materials.
The specific objectives of the SUPREME project are the following:
SO1. ROP of 1,2-campholide (CAM) to afford the new APE poly(campholide), PCAM
SO2. Synthesis of new APEs through ROCOP of β-elemene monoxide (BEM) and camphoric
anhydride (CA) to produce various polyesters with tunable functionality and rigidity
SO3. Post-modification of a functional APE obtained under SO2, and the study of the thermal, chemical and mechanical properties
The formation of β-elemene monoxide (BEM) was successfully achieved via selective epoxidation with metachloroperbenzoic acid (m-CPBA). In addition, the new β-elemene dioxide (BED) and trioxide (BET) were also obtained.
The ROCOP of BEM with phthalic anhydride (PA) was investigated in the presence of iron- and aluminium-amino triphenolate catalysts activated by PPNCl. The copolymerization of BEM with PA yields the highly functional low molecular weight hydroxyl-terminated polyester poly(BEM-alt-PA). ROCOP of BED and PA, under similar conditions, produces crosslinked PE without the use of an additional crosslinking agent. Post-modification of the new functional polyester was achieved by selective epoxidation of the pendant double bonds in the poly(BEM-alt-PA) structure and, depending on the reaction conditions, the corresponding poly(BED-alt-PA) and poly(BET-alt-PA) were obtained.
Thermal analyses conducted on the pristine and the post-functionalized materials showed that the glass transition temperature can be modulated in a temperature range of more than 50 ºC. In particular, it is possible to reach values similar to the Tg of the crosslinked PE obtained from direct ROCOP of BED with PA preserving the linear structure of the terpen-based polyester.
The ROCOP of BEM with phthalic anhydride (PA) was investigated in the presence of iron- and aluminium-amino triphenolate catalysts activated by PPNCl. The copolymerization of BEM with PA yields the highly functional low molecular weight hydroxyl-terminated polyester poly(BEM-alt-PA). ROCOP of BED and PA, under similar conditions, produces crosslinked PE without the use of an additional crosslinking agent. Post-modification of the new functional polyester was achieved by selective epoxidation of the pendant double bonds in the poly(BEM-alt-PA) structure and, depending on the reaction conditions, the corresponding poly(BED-alt-PA) and poly(BET-alt-PA) were obtained.
Thermal analyses conducted on the pristine and the post-functionalized materials showed that the glass transition temperature can be modulated in a temperature range of more than 50 ºC. In particular, it is possible to reach values similar to the Tg of the crosslinked PE obtained from direct ROCOP of BED with PA preserving the linear structure of the terpen-based polyester.
Despite the current efforts in the assessment of new bio-based polyesters, their industrial production is currently dominated by few biopolymers, such as poly(3-hydroxybutyrate) (PHB) and polylactide (PLA). The properties of these semi-crystalline PEs are usually tuned by copolymerization with other (often petrol-based) comonomers. With the SUPREME project we demonstrated that the preparation of functional polyesters based on bio-derived terpene such as β-elemene is possible. The presence of double-bonds functional groups, originally embedded in the terpene structure, allowed the easy post-modification of the new polyester. Such modification resulted in the possibility to finely tune the thermal properties of the polymeric material without the use of different co-monomeric structures. These results will be of impact in the field of biopolymers, giving a new impetus on the search for other terpene-based monomers with similar properties. Also, the use of bio-derived polyesters with controllable thermal properties may help in render more sustainable those processes in which these polymeric materials are used, such as the low-molecular weight polyester-polyols based production of polyurethanes.
The SUPREME project will also have a strong impact in the researcher future career. Indeed, at the completion of the project, the researcher profile is mature enough for submitting applications for tenure track positions, setting the stage for the creation of his own research group.
The SUPREME project will also have a strong impact in the researcher future career. Indeed, at the completion of the project, the researcher profile is mature enough for submitting applications for tenure track positions, setting the stage for the creation of his own research group.