Advances in Synthesis and Applications of Polymeric Biorenewable Materials via Metal Catalyzed Polymerizations

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Chemistry".

Deadline for manuscript submissions: closed (15 January 2023) | Viewed by 9712

Special Issue Editors


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Guest Editor
Department of Biology and Geology, Inorganic Physics and Chemistry, Rey Juan Carlos University (URJC), 28032 Madrid, Spain
Interests: organometallic chemistry; polymer chemistry; biorenewable materials; catalysis

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Guest Editor
Física y Química Inorgánica, Departamento de Biología y Geología, Universidad Rey Juan Carlos, 28933 Móstoles, Spain
Interests: synthesis of organometallic complexes as catalysts. CO2 valorization, synthesis of poly(lactide)s, cyclic carbonates and poly(carbonate)s

Special Issue Information

The traditional linear-economy model based on the indiscriminate use of our natural resources for the continued production of goods and services is causing a severe impact on the economy, society, and environment. Transforming this approach into a circular economy model that provides a rational use of raw materials and limits waste production and energy consumption constitutes a real challenge for scientists in this new century. In particular, chemistry plays an important role in meeting this challenge by optimizing industrial processes, enhancing the atom economy and reducing wastes, and providing products in a more energy-efficient mode through the employment of greener techniques. In this sense, the role of a catalyst is crucial for providing more efficient and cleaner synthetic routes of new and existing polymeric products. One of the most important and ubiquitous materials in our economy are plastics, which are present in many applications in our daily lives. Unfortunately, the way in which plastics are currently produced from fossil feedstocks fails to capture the benefits of applying a circular approach model. Therefore, in recent decades, there has been an increasing awareness of the development of alternative routes for the production of these materials, based on more sustainable and renewable materials as a replacement of petrochemical sources. The present Special Issue comprises the most recent advances accomplished in the field of the production of sustainable polymers obtained from renewable carbon feedstocks (e.g., biomass, CO2). This issue aims at collecting original studies as full papers or short communications, which highlight the challenge of designing efficient catalysts capable of producing applied polymers in homogeneous or heterogeneous conditions, as well as the discussion of their physical and chemical properties. Mechanistic studies or the use of density functional theory (DFT) calculations to rationalize these processes are also welcomed.

Keywords

  • efficient catalysts
  • biodegradable polymers
  • sustainable and renewable materials
  • homogeneous and heterogeneous catalysis

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Published Papers (4 papers)

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Research

21 pages, 5180 KiB  
Article
Density Functional Theory Analysis of the Copolymerization of Cyclopropenone with Ethylene Using a Palladium Catalyst
by Chenggen Zhang, Shuyuan Yu, Fei Wang, Fuping Wang, Jian Cao, Huimin Zheng, Xiaoyu Chen and Aijin Ren
Polymers 2022, 14(23), 5273; https://doi.org/10.3390/polym14235273 - 2 Dec 2022
Cited by 4 | Viewed by 1551
Abstract
Density functional theory has been used to elucidate the mechanism of Pd copolymerization of cyclopropenone with ethylene. The results reveal that introducing ethylene and cyclopropenone to Pd catalyst is thermodynamically feasible and generates the α,β-unsaturated ketone unit (UnitA). Cis-mode insertion and Path [...] Read more.
Density functional theory has been used to elucidate the mechanism of Pd copolymerization of cyclopropenone with ethylene. The results reveal that introducing ethylene and cyclopropenone to Pd catalyst is thermodynamically feasible and generates the α,β-unsaturated ketone unit (UnitA). Cis-mode insertion and Path A1a are the most favorable reaction routes for ethylene and cyclopropenone, respectively. Moreover, cyclopropenone decomposition can generate CO in situ without a catalyst or with a Pd catalyst. The Pd-catalyzed decomposition of cyclopropenone exhibits a lower reaction barrier (22.7 kcal/mol) than its direct decomposition. Our study demonstrates that incorporating CO into the Pd catalyst can generate the isolated ketone unit (UnitB). CO is formed first; thereafter, UnitB is generated. Therefore, the total energy barrier of UnitB generation, accounting for the CO barrier, is 22.7 kcal/mol, which is slightly lower than that of UnitA generation (24.0 kcal/mol). Additionally, the possibility of copolymerizing ethylene, cyclopropenone, and allyl acetate (AAc) has been investigated. The free energy and global reactivity index analyses indicate that the cyclopropenone introduction reaction is more favorable than the AAc insertion, which is consistent with the experimental results. Investigating the copolymerization mechanism will help to develop of a functionalization strategy for polyethylene polymers. Full article
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14 pages, 3355 KiB  
Article
Ring-Opening Polymerization of L-Lactide Catalyzed by Potassium-Based Complexes: Mechanistic Studies
by Christian Rentero, Jesús Damián, Asier Medel, María Fernández-Millán, Yolanda Rusconi, Giovanni Talarico, Tomás Cuenca, Valentina Sessini and Marta E. G. Mosquera
Polymers 2022, 14(15), 2982; https://doi.org/10.3390/polym14152982 - 23 Jul 2022
Cited by 5 | Viewed by 2846
Abstract
Two non-toxic potassium compounds, 1 and 2, with a commercial oximate ligand have been prepared and fully spectroscopically characterized. Their activity as catalysts for the ring-opening polymerization (ROP) process of LLA has been studied, showing that they are extremely active and able [...] Read more.
Two non-toxic potassium compounds, 1 and 2, with a commercial oximate ligand have been prepared and fully spectroscopically characterized. Their activity as catalysts for the ring-opening polymerization (ROP) process of LLA has been studied, showing that they are extremely active and able to polymerize the monomer in a few minutes. For derivative 2, the presence of a crown ether in the potassium coordination sphere affects the nuclearity of the compound and consequently its solubility, with both aspects having an influence in the polymerization process. Detailed studies of the polymerization mechanism have been performed, and an unusual anionic mechanism was observed in absence of a co-initiator. Indeed, the monomer deprotonation generates a lactide enolate, which initiates the polymerization propagation. On the contrary, when a 1:1 ratio of cat:BnOH is used, a mixture of mechanisms is observed, the anionic mechanism and the activated monomer one, while from a cat:BnOH ratio of 1:2 and over, only the activated monomer mechanism is observed. Full article
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16 pages, 8250 KiB  
Article
Synthesis of High Molecular Weight Stereo-Di-Block Copolymers Driven by a Co-Initiator Free Catalyst
by Carmen Moya-Lopez, Ivan Bravo, José A. Castro-Osma, David Chapron, Patrice Bourson, Christelle Vagner, Marianne Cochez, Nils Leoné, Agustín Lara-Sánchez, Carlos Alonso-Moreno and Daniel Hermida-Merino
Polymers 2022, 14(2), 232; https://doi.org/10.3390/polym14020232 - 7 Jan 2022
Cited by 3 | Viewed by 2260
Abstract
Stereo-diblock copolymers of high molecular weight polylactide (PLA) were synthetized by the one pot-sequential addition method assisted by a heteroscorpionate catalyst without the need of a co-initiator. The alkyl zinc organometallic heteroscorpionate derivative (Zn(Et)(κ3-bpzteH)] (bpzteH = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-para-tolylethoxide) proved to assist in [...] Read more.
Stereo-diblock copolymers of high molecular weight polylactide (PLA) were synthetized by the one pot-sequential addition method assisted by a heteroscorpionate catalyst without the need of a co-initiator. The alkyl zinc organometallic heteroscorpionate derivative (Zn(Et)(κ3-bpzteH)] (bpzteH = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-para-tolylethoxide) proved to assist in the mechanism of reaction following a coordination-insertion process. Kinetic studies along with the linear correlation between monomer and number average molecular weight (Mn) conversion, and the narrow polydispersities supported the truly living polymerization character of the initiator, whereas matrix-assisted laser desorption/Ionization-time of flight (MALDI-TOF) studies showed a very low order of transesterification. The high stereo-control attained for the afforded high molecular weight derivatives was revealed by homonuclear decoupled 1H NMR spectra and polarimetry measurements. The nanostructure of the PLA derivatives was studied by both wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) and the stereocomplex phase of the PLA stereo-diblock copolymers was successfully identified. Full article
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13 pages, 1412 KiB  
Article
Efficient Bulky Organo-Zinc Scorpionates for the Stereoselective Production of Poly(rac-lactide)s
by Marta Navarro, Andrés Garcés, Luis F. Sánchez-Barba, Felipe de la Cruz-Martínez, Juan Fernández-Baeza and Agustín Lara-Sánchez
Polymers 2021, 13(14), 2356; https://doi.org/10.3390/polym13142356 - 19 Jul 2021
Cited by 5 | Viewed by 2165
Abstract
The direct reaction of the highly sterically demanding acetamidinate-based NNN′-scorpionate protioligand Hphbptamd [Hphbptamd = N,N′-di-p-tolylbis(3,5-di-tertbutylpyrazole-1-yl)acetamidine] with one equiv. of ZnMe2 proceeds in high yield to the mononuclear alkyl zinc complex [ZnMe(κ3-phbpt [...] Read more.
The direct reaction of the highly sterically demanding acetamidinate-based NNN′-scorpionate protioligand Hphbptamd [Hphbptamd = N,N′-di-p-tolylbis(3,5-di-tertbutylpyrazole-1-yl)acetamidine] with one equiv. of ZnMe2 proceeds in high yield to the mononuclear alkyl zinc complex [ZnMe(κ3-phbptamd)] (1). Alternatively, the treatment of the corresponding lithium precursor [Li(phbptamd)(THF)] with ZnCl2 yielded the halide complex [ZnCl(κ3-phbptamd)] (2). The X-ray crystal structure of 1 confirmed unambiguously a mononuclear entity in these complexes, with the zinc centre arranged with a pseudotetrahedral environment and the scorpionate ligand in a κ3-coordination mode. Interestingly, the inexpensive, low-toxic and easily prepared complexes 1 and 2 resulted in highly efficient catalysts for the ring-opening polymerisation of lactides, a sustainable bio-resourced process industrially demanded. Thus, complex 1 behaved as a single-component robust initiator for the living and immortal ROP of rac-lactide under very mild conditions after a few hours, reaching a TOF value up to 5520 h−1 under bulk conditions. Preliminary kinetic studies revealed apparent zero-order dependence on monomer concentration in the absence of a cocatalyst. The PLA materials produced exhibited narrow dispersity values, good agreement between the experimental Mn values and monomer/benzyl alcohol ratios, as well as enhanced levels of heteroselectivity, reaching Ps values up to 0.74. Full article
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