Polymerization Of CO2 Research Articles

Tetrameric self-assembling of water-lean solvents enables carbamate anhydride-based CO2 capture chemistry

Carbon capture, utilization and storage is a key yet cost-intensive technology for the fight against climate change. Single-component water-lean solvents have emerged as promising materials for post-combustion CO2 capture, but little is known regarding their mechanism of action. Here we present a combined experimental and modelling study of single-component water-lean solvents, and we find that CO2 capture is accompanied by the self-assembly of reverse-micelle-like tetrameric clusters in solution. This spontaneous aggregation leads to stepwise cooperative capture phenomena with highly contrasting mechanistic and thermodynamic features. The emergence of well-defined supramolecular architectures displaying a hydrogen-bonded internal core, reminiscent of enzymatic active sites, enables the formation of CO2-containing molecular species such as carbamic acid, carbamic anhydride and alkoxy carbamic anhydrides. This system extends the scope of adducts and mechanisms observed during carbon capture. It opens the way to materials with a higher CO2 storage capacity and provides a means for carbamates to potentially act as initiators for future oligomerization or polymerization of CO2.

Surface activated zinc-glutarate for the copolymerization of CO2 and epoxides.

Zinc-glutarate (ZnGA) is a promising catalyst that can form polymers from CO2 and epoxides, thereby contributing to the development of CO2 utilization technologies and future sustainability. One of the obstacles to commercializing ZnGA in polymer industries is its low catalytic activity. In this study, we introduced activated two-dimensional (2D) ZnGA to improve its catalytic activity in polymerization. The morphology-controlled 2D ZnGA was treated with H3Co(CN)6, and a porous granular-type Co-modified ZnGA (Co-ZnGA) was prepared. The morphology of 2D ZnGA is a prerequisite for the activation by H3Co(CN)6. The catalytic properties of Co-ZnGA were evaluated by copolymerization of various epoxides and CO2, and exhibited catalytic activity of 855, 1540, 1190, and 148 g g-cat-1 with propylene oxide, 1,2-epoxyhexane, 1,2-epoxybutane, and styrene oxide, respectively. This study provided a new strategy using 2D ZnGA instead of conventional ZnGA for increasing the catalytic activity in CO2 polymerization.

Iron-catalyzed reactions of CO2 and epoxides to yield cyclic and polycarbonates

The catalytic coupling and polymerization of CO2 and epoxides has been studied for over 50 years. While traditionally dominated by catalytic systems containing cobalt, chromium, and zinc, the use of iron catalysts has emerged in the past 10 years. This review provides an overview of the homogeneous iron-catalyzed transformations of carbon dioxide and epoxides to yield cyclic and/or polycarbonates. It is important to note the potential for cyclic carbonates to be used as monomers for polymer formation via transesterification or by ring-opening polymerization in some cases, e.g., cyclohexene carbonate. Typical catalytic systems are composed of a Lewis acidic iron center and an anionic nucleophilic source, either through an anionic group weakly bound to the metal center or the addition of an external cocatalyst, cooperatively described as a binary catalytic system. This review is divided into two sections: (1) iron catalysts for cyclic carbonates and (2) iron catalysts for polycarbonates. At the end of each section, a table summarizes each catalytic system and the reaction conditions utilized in an attempt to provide a clearer comparison across the literature. Focus is given to highlighting differences in product selectivity, reaction conditions, and relative amounts of cocatalyst used. The use of iron catalysts in CO2/epoxide chemistry has been less explored compared with zinc, cobalt, and chromium catalysts. This review highlights recent examples including iron complexes that deoxygenate epoxides in situ and geometry-dependent selectivity towards either polycarbonate or cyclic carbonate production. Reaction conditions (temperature, CO2 pressure, and amount of nucleophilic cocatalyst) and catalyst structure are all critical in accessing efficient catalysis for polycarbonate formation.

Green Monomer of CO2 and Alkyne-based Four-component Tandem Polymerization toward Regio- and Stereoregular Poly(aminoacrylate)s

Green monomers, such as carbon dioxide (CO2), are closely related to our daily life and highly desirable to be transferred to functional polymers with diverse structures and versatile properties because they are abundant, cheap, nontoxic, renewable, and sustainable. However, the polymerizations based on these green monomers are to be further developed. In this work, a facile CO2 and alkyne-based one-pot, two-step, four-component tandem polymerization was successfully established. The polymerization of CO2, diynes, alkyl dihalides, and primary/secondary amines can proceed under mild reaction conditions and regio- and stereoregular poly(aminoacrylate)s with good solubility and thermal stability were obtained in high yields (up to 95%). Notably, distinctly different stereoregularity of resultant poly(aminoacrylate)s was realized via using primary or secondary amines. Using the former would readily generate polymers with 100% Z-isomers, whereas the latter furnished products with over 95% E-isomers. Through different monomer combination, the polymers with tunable structures and properties were obtained. Moreover, the tetraphenylethene units containing poly(aminoacrylate)s, showing the unique aggregation-induced emission characteristics, could function as a fluorescent probe for sensitive explosive detection. Thus, this work not only develops a facile CO2 and alkyne-based multicomponent tandem polymerization but also provides a valuable strategy to fine-tune the polymer structures and properties, which could be potentially applied in diverse areas.

Is the Formation of Poly-CO2 Stabilized by Lewis Base Moieties in N- and S-Doped Porous Carbon?

The polymerization of CO2 by Lewis basic moieties has been recently proposed to account for the high adsorption ability of N and S-doped porous carbon materials formed from the pyrolysis of sulfur or nitrogen containing polymers in the presence of KOH. Ab initio calculations performed on the ideal CO2 tetramer complex LB-(CO2)4 (LB = NH3, H2O, H2S) showed no propensity for stabilization. A weak association is observed using Lewis acid species bound to oxygen (LA = H+, AlF3, AlH3, B4O6); however, the combination of a Lewis acid and base does allow for the formation of polymerized CO2 (i.e., LB-C(O)O-[C(O)O]n-C(O)O-LA). While the presence of acid moieties in porous carbon is well known, and borate species are experimentally observed in KOH activated porous carbon materials, the low stability of the oligomers calculated herein, is insufficient to explain the reported poly-CO2.

Polyurea-supported metal nanocatalysts: Synthesis, characterization and application in selective hydrogenation of o-chloronitrobenzene

Polyurea (PU) spheres with size of 2–10μm were derived through the polymerization of CO2 with 1,4-butanediamine, and characterized by FTIR spectroscopy, scanning electron microscopy and TG analysis. It was demonstrated that the PU spheres displayed flower-like morphology with the betel thickness around 30nm, and they had high thermal stability. The resultant PU spheres were used to immobilize metal particles, and a series of PU-supported metal nanocatalysts including Pt/PU, Au/PU, Pd/PU were prepared via just mixing the metal precursors with the PU spheres in water, followed by the reduction of metal ions by NaBH4. Transmission electron microscopy examination indicated that the metal nanoparticles were distributed uniformly on the surface of the PU spheres with mean particle size less than 3.0nm, and the Pt particles existed mainly in the form of metallic state as confirmed by the X-ray photoelectron spectroscopy analysis. The performance of the Pt/PU catalyst was tested in the catalytic hydrogenation of o-chloronitrobenzene, and a high selectivity of 99.5% toward o-chloroaniline at complete conversion of o-chloronitrobenzene was obtained at room temperature.

Bases for Understanding Polymerization under Pressure: The Practical Case of CO2

We present a novel quantitative strategy for monitoring chemical bonding transformations in solids from the topology of their electronic structure. Developed in the context of the electron localization function formalism, it provides an unambiguous characterization of long-range interactions and bond formation. Charge flux between electron localization regions is found to hold the key for identifying the nature of the interaction between the chemically meaningful entities in the solid (valence shells, lone pairs, molecules, etc.). Because of the wide range of interesting properties that high pressure induces in molecular solids, we illustrate the potentialities of our strategy to unveil controversial questions involved in the bond reorganization along the polymerization of CO2. Our study confirms that the topology of the bonding network in the pseudopolymeric phases points toward the incipient formation of the new bonds in the higher pressure polymers. This transformation is identified as a synchronic weakening of the intramolecular (C==O) double bond and the birth of a new intermolecular C--O bond controlled by the oxygen lone pairs. Overall, the relationship that this type of analysis establishes between different polymorphs of the phase diagram could be further exploited for the prediction of the coordination of high pressure phases, opening new avenues for experimental synthesis and structure indexation.