Polymerization Catalysts Research Articles

Toyobo GS Catalyst, an eco-friendly aluminum catalyst for polyester polymerization, receives recognition for APR Design for Recyclability

Toyobo GS Catalyst, an eco-friendly aluminum catalyst for polyester polymerization, receives recognition for APR Design for Recyclability

A high-performance liquid Ru-based metathesis catalyst for the ring-opening metathesis polymerization of dicyclopentadiene

A high-performance liquid Ru-based metathesis catalyst for the ring-opening metathesis polymerization of dicyclopentadiene

La[N(SiMe3)2]3: A highly active catalyst for the ring‐opening polymerization of trimethylene carbonate

AbstractPoly(trimethylene carbonate) (PTMC) has been extensively researched as biomaterials due to its biocompatibility and biodegradability. However, its limited mechanical strength has restricted its application in various commodity materials, necessitating an enhancement through higher molecular weight. A traditional method for synthesizing high molecular weight PTMC mainly involves SnOct2 as a polymerization catalyst, conducting trimethylene carbonate (TMC) polymerization at high temperatures over several days. This approach consumes significant time and energy, making further molecular weight enhancement challenging. In this study, we polymerized TMC using the highly active catalyst La[N(SiMe3)2]3. We have successfully synthesized high molecular weight PTMC (Mn >500,000) within minutes at room temperature. The tensile test results of PTMC molding films demonstrated strain‐induced crystallization specific to high molecular weight PTMC.

Highly Enantioselective Polymerization of β-Butyrolactone by a Bimetallic Magnesium Catalyst: An Interdependent Relationship Between Favored and Unfavored Enantiomers.

Herein, we report that (S,S)-prophenolMg2(μ-OnBu)(THF)2 ((S,S)-1, prophenol = (S,S)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol) is a highly enantioselective (kR/kS = 140) precatalyst for ring-opening polymerization of rac-β-butyrolactone (β-BL) to isotactic poly(3-hydroxybutyrate) (i-PHB), a high performance, biodegradable polyester. Precatalyst (S,S)-1 polymerizes (R)-β-BL with an inversion of stereochemistry to (S)-PHB with a m% (percentage of adjacent linkages with a meso configuration) of 98% at 41% conversion and Tm of 165 °C under a variety of conditions. Complex (S,S)-1 demonstrates unique polymerization kinetics, as it does not polymerize the preferred enantiomer, (R)-β-BL, alone. Mechanistic studies revealed that (S)-β-BL is needed to convert (S,S)-1 into the active enantioselective polymerization catalyst. To the best of our knowledge, (S,S)-1 produces i-PHB with the highest degree of isotacticity observed from a polymerization of rac-β-BL. This study informs the design and understanding of future enantioselective and earth-abundant metal catalysts for ring-opening polymerization of β-lactones.

Leveraging Triphenylphosphine-Containing Polymers to Explore Design Principles for Protein-Mimetic Catalysts.

Complex interactions between noncoordinating residues are significant yet commonly overlooked components of macromolecular catalyst function. While these interactions have been demonstrated to impact binding affinities and catalytic rates in metalloenzymes, the roles of similar structural elements in synthetic polymeric catalysts remain underexplored. Using a model Suzuki-Miyuara cross-coupling reaction, we performed a series of systematic studies to probe the interconnected effects of metal-ligand cross-links, electrostatic interactions, and local rigidity in polymer catalysts. To achieve this, a novel bifunctional triphenylphosphine acrylamide (BisTPPAm) monomer was synthesized and evaluated alongside an analogous monofunctional triphenylphosphine acrylamide (TPPAm). In model copolymer catalysts, increased initial reaction rates were observed for copolymers untethered by Pd complexation (BisTPPAm-containing) compared to Pd-cross-linked catalysts (TPPAm-containing). Further, incorporating local rigidity through secondary structure-like and electrostatic interactions revealed nonmonotonic relationships between composition and the reaction rate, demonstrating the potential for tunable behavior through secondary-sphere interactions. Finally, through rigorous cheminformatics featurization strategies and statistical modeling, we quantitated relationships between chemical descriptors of the substrate and reaction conditions on catalytic performance. Collectively, these results provide insights into relationships among the composition, structure, and function of protein-mimetic catalytic copolymers.

Particle size effects on silyl‐chromate/VOx/silica bimetallic catalyst for UHMWPE/HDPE in‐reactor blends

AbstractIn this work, four kinds of silica with similar textural properties but different particle size (PS) from 6 to 60 μm were selected as support to prepare silyl‐chromate/VOx/silica bimetallic catalysts for ethylene polymerization, thus making it possible to conduct convincing investigation on the effects of catalyst PS over catalytic behaviors and polymer properties. It is found, owing to mass‐ and heat‐transfer limitations, the catalysts with smaller PS showed higher initial activity, while the deactivation in the later stage was more remarkable. Meanwhile, catalysts with smaller PS synthesized bimodal ultrahigh molecular weight polyethylene/high‐density polyethylene in‐reactor blends (UHMWPE/HDPE IRBs) with higher molecular weight (MW) and narrower molecular weight distribution (MWD). Four PE sample couples with MW increasing from 5 × 105 to 10 × 105 g mol−1 and PS from 40 to 460 μm were selected for tensile and rheological tests. For each couple with similar MW and MWD, the sample with smaller PS always had larger tensile strength and breaking elongation. The cryogenically fractured surface of the samples made by smaller PE particles showed fewer delamination defects and unfused small particles. The rheological results indicate that higher homogeneity was achieved for the sample with smaller PS, which was reflected by the unexpected higher viscosity and storage modulus.

Development of Pd-immobilized porous polymer catalysts via Bayesian optimization

Development of Pd-immobilized porous polymer catalysts via Bayesian optimization

Palladium-anchored calix[4]arene-derived porous organic polymer towards efficient hydrolytic cleavage of carbon disulfide

The release of carbon disulfide can have adverse effects on our environment and human health. The stability of carbon disulfide and the slow kinetics of hydrolysis can make it challenging to achieve efficient and practical cleavage of the CS bonds. Herein, a calix[4]arene-based porous organic polymer (CPOP-1) is innovatively synthesized through an optimized polycondensation reaction using C-Methylcalix[4]resorcinarene and hexafluoro-hexaazatriphenylene as monomers. Subsequently, palladium-induced calix[4]arene-based porous organic polymer was also synthesized via strong Pd−N coordination bonds to construct the metal-induced porous catalyst (CPOP-2). The polymeric catalyst active center [Pd2+(N^N)(NO3-)2] demonstrated outstanding catalytic hydrolysis performance (11.14 μmol g-1 h-1) in 10.5 h which is significantly enhanced by ca.13.2 times as compared to reported mononuclear Bpy-Pd(NO3)2, and 7.07 times than model trinuclear complex catalyst HATN-Pd-1, respectively. The control experiments revealed that POP catalysts showcased robust stability, prolonged effectiveness, and feasible recyclability during the hydrolytic cleavage of carbon disulfide at room temperature in aqueous solutions. Furthermore, the coordination environment of [Pd2+(N^N)] was validated through XPS, EXAFS, and isotope labeling measurements, and the hydrolysis cleavage products were confirmed e. g. CO2, sulfide, and protons. More importantly, a reaction mechanism was formulated coupled with theoretical calculations, and simulations. The proposed mechanism involves sequential OH- nucleophilic attacks on the carbon atoms of insert-coordinated CS2 and COS, leading to the cleavage of double CS bonds and the formation of CO bonds. The concurrent dissociation of the C−S bond and liberation of CO2 result in an intermediate structure characterized by [(N^N)Pd2+](SH-)2. This intermediate motif serves as the source of the thermodynamic driving force for the reaction.

Green fuel production from waste fried sunflower oil using reusable mesoporous COP-KOH catalyst with a kinetic study

Declining fossil fuel reserves and fluctuating petroleum prices have prompted global research efforts to develop clean, renewable, and sustainable alternatives to traditional fossil fuels. In this study, a reusable and eco-friendly activation catalyst was designed by combining KOH with a polymer. A series of three polymer catalysts were synthesized, and their catalytic activities were compared with those of COP-KOH, COP-K3PO4 and COP-KF. It was found that the prepared COP-KOH catalyst showed the highest activity. The catalyst was characterized by FT-IR, which confirmed the presence of potassium support successfully coordinated on the COP. Additional analyses included N2 and BET, XPS, SEM, mapping, and basicity measurement by ICP analysis. The prepared catalysts a possessed mesoporous structure, high surface area of 4.2961 m2/g−1, pore volume of 2.2439 m2/g−1, and high basicity. Here, the activity and stability of the potassium modified mesoporous polymer COP-KOH catalyst in green fuel synthesis from waste fried sunflower oil was evaluated. The green fuel conversion rate of 96.42 % was achieved under optimal reaction conditions, with a molar ratio of 6:1 methanol to fried sunflower oil, a catalyst concentration of 85 wt%, a reaction temperature of 61 °C, and a reaction time of 4.5 h. A satisfactory yield of 92.1 % was obtained after use for four consecutive cycles without significant deactivation, and after the fourth cycle catalyst was reactivated with KOH. The characteristic differences in the FT-IR results of the fresh catalyst, used catalyst, and re-activated COP-KOH catalyst, indicated the mode of interaction between the catalyst and reactants. The kinetics of the transesterification reaction was also determined, and the activation energy was found to range from 20.9 to 23.4 kJ.mol−1. The properties of the green fuel were found to be in good agreement with the ASTM D6571-02 standard. The catalyst is recyclable, and using inexpensive feedstock makes the overall process more cost-effective and environmentally friendly.

Organotin copolymers as polymeric crosslinking catalysts

Organotin copolymers as polymeric crosslinking catalysts

Formation of FeNi-based nanowire-assembled superstructures with tunable anions for electrocatalytic oxygen evolution reaction

Anion modification has been considered as a strategy to improve water splitting efficiency upon oxygen evolution reaction (OER). However, constructing a novel catalysis system with high catalytic activity and precise structures is still a huge challenge due to the tedious procedure of precursor synthesis and anion selection. Here, a bimetallic (FeNi) nanowire self-assembled superstructure was synthesized using the Hoffmann rearrangement method, and then functionalized with four anions (P, Se, S, and O). Notably, the Fe3Se4/Ni3Se4 catalyst shows a high conductivity, enhances the adsorption of intermediate products, accelerates the rate-determining step, and consequently results to improved electrocatalytic performance. Using the Fe3Se4/Ni3Se4 catalyst exhibits enhanced performance with overpotential of 316 mV at 10 mA/cm2, in stark contrast to Fe2P/Ni2P (357 mV), Fe7S8/NiS (379 mV), and Fe3O4/NiO (464 mV). Moreover, the formation mechanism of superstructure and the relationship between electronegativities and electrocatalytic properties, are elucidated. Accordingly, this work provides an efficient approach to Hoffmann-type coordination polymer catalyst for oxygen evolution towards a near future.

Ring-opening polymerization of lactide catalyzed using metal-coordinated enzyme-like amino acid assemblies.

Polylactide (PLA), a biocompatible and biodegradable polymer, is widely used in diverse biomedical applications. However, the industry standard for converting lactide into PLA involves toxic tin (Sn)-based catalysts. To mitigate the use of these harmful catalysts, other environmentally benign metal-containing agents for efficient lactide polymerization have been studied, but these alternatives are hindered by complex synthesis processes, reactivity issues, and selectivity limitations. To overcome these shortcomings, we explored the catalytic activity of Cu-(Phe)2 and Zn-(Phe)2 metal-amino acid co-assemblies as potential catalysts of the ring-opening polymerization (ROP) of lactide into PLA. Catalytic activity of the assemblies was monitored at different temperatures and solvents using 1H-NMR spectroscopy to determine the catalytic parameters. Notably, Zn-(Phe)2 achieved >99% conversion of lactide to PLA within 12 h in toluene under reflux conditions and was found to have first-order kinetics, whereas Cu-(Phe)2 exhibited significantly lower catalytic activity. Following Zn-(Phe)2-mediated catalysis, the resulting PLA had an average molecular weight of 128 kDa and a dispersity index of 1.25 as determined by gel permeation chromatography. Taken together, our minimalistic approach expands the realm of metal-amino acid-based supramolecular catalytic nanomaterials useful in the ROP of lactide. This advancement shows promise for the future design of simplified biocatalysts in both industrial and biomedical applications.

Thermally Stable and Chemically Recyclable Poly(ketal-ester)s Regulated by Floor Temperature.

Chemical recycling to monomers (CRM) offers a promising closed-loop approach to transition from current linear plastic economy toward a more sustainable circular paradigm. Typically, this approach has focused on modulating the ceiling temperature (Tc) of monomers. Despite considerable advancements, polymers with low Tc often face challenges such as inadequate thermal stability, exemplified by poly(γ-butyrolactone) (PGBL) with a decomposition temperature of ∼200 °C. In contrast, floor temperature (Tf)-regulated polymers, particularly those synthesized via the ring-opening polymerization (ROP) of macrolactones, inherently exhibit enhanced thermodynamic stability as the temperature increases. However, the development of those Tf regulated chemically recyclable polymers remains relatively underexplored. In this context, by judicious design and efficient synthesis of a biobased macrocyclic diester monomer (HOD), we developed a type of Tf -regulated closed-loop chemically recyclable poly(ketal-ester) (PHOD). First, the entropy-driven ROP of HOD generated high-molar mass PHOD with exceptional thermal stability with a Td,5% reaching up to 353 °C. Notably, it maintains a high Td,5% of 345 °C even without removing the polymerization catalyst. This contrasts markedly with PGBL, which spontaneously depolymerizes back to the monomer above its Tc in the presence of catalyst. Second, PHOD displays outstanding closed-loop chemical recyclability at room temperature within just 1 min with tBuOK. Finally, copolymerization of pentadecanolide (PDL) with HOD generated high-performance copolymers (PHOD-co-PPDL) with tunable mechanical properties and chemical recyclability of both components.

Hollow Microporous Organic Polymer@Hypercrosslinked Polymer Catalysts Bearing N-Heterocyclic Carbene–Iron Species for the Synthesis of Biomass-Derived Polymer Platforms

Hollow Microporous Organic Polymer@Hypercrosslinked Polymer Catalysts Bearing <i>N</i>-Heterocyclic Carbene–Iron Species for the Synthesis of Biomass-Derived Polymer Platforms

Linker Mediated Electronic-State Manipulation of Conjugated Organic Polymers Enabling Highly Efficient Oxygen Reduction.

Conjugated polymers with tailorable composition and microarchitecture are propitious for modulating catalytic properties and deciphering inherent structure-performance relationships. Herein, we report a facile linker engineering strategy to manipulate the electronic states of metallophthalocyanine conjugated polymers and uncover the vital role of organic linkers in facilitating electrocatalytic oxygen reduction reaction (ORR). Specifically, a set of cobalt phthalocyanine conjugated polymers (CoPc-CPs) wrapped onto carbon nanotubes (denoted CNTs@CoPc-CPs) are judiciously crafted via in situ assembling square-planar cobalt tetraaminophthalocyanine (CoPc(NH2)4) with different linear aromatic dialdehyde-based organic linkers in the presence of CNTs. Intriguingly, upon varying the electronic characteristic of organic linkers from terephthalaldehyde (TA) to 2,5-thiophenedicarboxaldehyde (TDA) and then to thieno/thiophene-2,5-dicarboxaldehyde (bTDA), their corresponding CNTs@CoPc-CPs exhibit gradually improved electrocatalytic ORR performance. More importantly, theoretical calculations reveal that the charge transfer from CoPc units to electron-withdrawing linkers (i.e., TDA and bTDA) drives the delocalization of Co d-orbital electrons, thereby downshifting the Co d-band energy level. Accordingly, the active Co centers with more positive valence state exhibit optimized binding energy toward ORR-relevant intermediates and thus a balanced adsorption/desorption pathway that endows significant enhancement in electrocatalytic ORR. This work demonstrates a molecular-level engineering route for rationally designing efficient polymer catalysts and gaining insightful understanding of electrocatalytic mechanisms.

Linker Mediated Electronic‐State Manipulation of Conjugated Organic Polymers Enabling Highly Efficient Oxygen Reduction

AbstractConjugated polymers with tailorable composition and microarchitecture are propitious for modulating catalytic properties and deciphering inherent structure‐performance relationships. Herein, we report a facile linker engineering strategy to manipulate the electronic states of metallophthalocyanine conjugated polymers and uncover the vital role of organic linkers in facilitating electrocatalytic oxygen reduction reaction (ORR). Specifically, a set of cobalt phthalocyanine conjugated polymers (CoPc‐CPs) wrapped onto carbon nanotubes (denoted CNTs@CoPc‐CPs) are judiciously crafted via in situ assembling square‐planar cobalt tetraaminophthalocyanine (CoPc(NH2)4) with different linear aromatic dialdehyde‐based organic linkers in the presence of CNTs. Intriguingly, upon varying the electronic characteristic of organic linkers from terephthalaldehyde (TA) to 2,5‐thiophenedicarboxaldehyde (TDA) and then to thieno/thiophene‐2,5‐dicarboxaldehyde (bTDA), their corresponding CNTs@CoPc‐CPs exhibit gradually improved electrocatalytic ORR performance. More importantly, theoretical calculations reveal that the charge transfer from CoPc units to electron‐withdrawing linkers (i.e., TDA and bTDA) drives the delocalization of Co d‐orbital electrons, thereby downshifting the Co d‐band energy level. Accordingly, the active Co centers with more positive valence state exhibit optimized binding energy toward ORR‐relevant intermediates and thus a balanced adsorption/desorption pathway that endows significant enhancement in electrocatalytic ORR. This work demonstrates a molecular‐level engineering route for rationally designing efficient polymer catalysts and gaining insightful understanding of electrocatalytic mechanisms.

Positional heterogenization effect in salicylaldimine nickel catalyzed ethylene polymerization

Positional heterogenization effect in salicylaldimine nickel catalyzed ethylene polymerization

Orbital-scale understanding of the surface effect of the MgCl2 in the Ziegler–Natta catalyst for ethylene polymerization: A computational study

Ziegler-Natta catalyst is a widely used olefin polymerization catalyst in petrochemical industries. However, the role of each catalyst component is not clear due to the complexity of composition and structure. MgCl2 is a suitable support for Ziegler-Natta catalyst because its crystal structure is similar to that of TiCl3, and the surface effect of MgCl2 in Ziegler-Natta catalyst system was explored in ethylene polymerization at the orbital scale. A series of the stable surface-supported catalysts with unsaturated coordination Mg2+ were used to simulate the mechanism of ethylene polymerization by the periodic density functional theory. This study found that MgCl2 with different surfaces regulates the activity of the catalyst by adjusting the d band centre of the catalyst active centre. This concept can be used to explain the surface effect of support in general catalysts.

Pore size modulation of cobalt-corrole-based porous organic polymers for boosted electrocatalytic oxygen reduction reaction

The highly active and selective oxygen reduction reaction (ORR) is vital to promote the performance of advanced energy conversion systems, such as fuel cells and other electrochemical devices. Porous framework materials have the capability to combine the catalytic performance of catalytic active units with their porous characteristics, making them promising oxygen reduction catalysts. However, due to the difficulty in designing and synthesizing catalytic active units, the pore size modulation of framework materials is primarily achieved by altering the linkers. We herein report the design and synthesis of three cobalt-corrole-based porous organic polymers (Co-POP-1, Co-POP-2 and Co-POP-3) with different pore sizes, which were obtained by extending 5,15-meso substituents of Co corroles. Compared to Co-POP-1 and Co-POP-2, Co-POP-3 has the largest pore size. Benefiting from the enhanced mass transfer and the highly exposed active sites, Co-POP-3 displayed remarkably boosted activity for the selective four-electron/four-proton (4e−/4 H+) ORR with a half-wave potential of E1/2 = 0.89 V versus reversible hydrogen electrode (RHE) in 0.1 M KOH solutions. This work not only presents a cobalt-corrole-based porous organic polymer catalyst with high ORR activity and selectivity but also provides a new strategy to moderate the pore size of porous framework materials.

Integrated model for accurate internal state estimation of polymer electrolyte membrane fuel cells

This study unveils a refined methodology for fuel cell behavior simulation. On the basis of three multiphysics models for the polymer membrane, catalyst layer, and mass transport, a new type of integrated model was developed. Using this model, the performance curves for various fuel cell states, charge transfer coefficient of reaction kinetics, concentration gradient inside the catalyst, and ion conductivity of the separator in the thickness direction for various fuel cell states were estimated. The proposed method can estimate microscale to macroscale fuel cell behavior with minimal computational effort while keeping the error relative to experimental data small by combining the most appropriate models to simulate each part of the fuel cell as needed.