Copolymerization Of CO2 Research Articles

Comparison of Different Approaches to Surface Functionalization of Biodegradable Polycaprolactone Scaffolds.

Due to their good mechanical stability compared to gelatin, collagen or polyethylene glycol nanofibers and slow degradation rate, biodegradable poly-ε-caprolactone (PCL) nanofibers are promising material as scaffolds for bone and soft-tissue engineering. Here, PCL nanofibers were prepared by the electrospinning method and then subjected to surface functionalization aimed at improving their biocompatibility and bioactivity. For surface modification, two approaches were used: (i) COOH-containing polymer was deposited on the PCL surface using atmospheric pressure plasma copolymerization of CO2 and C2H4, and (ii) PCL nanofibers were coated with multifunctional bioactive nanostructured TiCaPCON film by magnetron sputtering of TiC–CaO–Ti3POx target. To evaluate bone regeneration ability in vitro, the surface-modified PCL nanofibers were immersed in simulated body fluid (SBF, 1×) for 21 days. The results obtained indicate different osteoblastic and epithelial cell response depending on the modification method. The TiCaPCON-coated PCL nanofibers exhibited enhanced adhesion and proliferation of MC3T3-E1 cells, promoted the formation of Ca-based mineralized layer in SBF and, therefore, can be considered as promising material for bone tissue regeneration. The PCL–COOH nanofibers demonstrated improved adhesion and proliferation of IAR-2 cells, which shows their high potential for skin reparation and wound dressing.

Monomodal Ultrahigh-Molar-Mass Polycarbonate Homopolymers and Diblock Copolymers by Anionic Copolymerization of Epoxides with CO2

Whatever the chemistry used for the synthesis of aliphatic polycarbonates, in particular, those of high molar mass, the adventitious presence of water leads to bimodal GPC traces and affords polycarbonate samples of uncontrolled and unpredictable molar masses. It appears that among all reagents used in the copolymerization of CO2 and epoxides, CO2 is the most difficult one to dry. To address this issue, triisobutylaluminum (TiBA) was employed in this work to dry CO2 through a bubbling method; its drying capability was investigated in the context of the copolymerization of CO2 with epoxides initiated by onium chloride in the presence of triethylborane (TEB). It was then compared to the efficiency of other already reported drying agents such as phosphorus pentoxide, molecular sieves and commercially available CO2 purifiers. With TiBA-dried CO2, its copolymerizations respectively with propylene oxide (PO) and cyclohexene oxide (CHO) could be successfully achieved in a wide range of degrees of polymerization (DP), with the value of DP as high as 16000. Diblock copolymers poly(propylene carbonate-b-cyclohexene carbonate) (PPC-b-PCHC) could also be prepared through sequential addition of epoxide monomers. The polycarbonates obtained under the conditions were all well-defined as characterized by NMR, GPC, triple detector-GPC, and differential scanning calorimetry (DSC).

Surface Modification of a MOF-based Catalyst with Lewis Metal Salts for Improved Catalytic Activity in the Fixation of CO2 into Polymers

The catalyst zinc glutarate (ZnGA) is widely used in the industry for the alternating copolymerization of CO2 with epoxides. However, the activity of this heterogeneous catalyst is restricted to the outer surface of its particles. Consequently, in the current study, to increase the number of active surface metal centers, ZnGA was treated with diverse metal salts to form heterogeneous, surface-modified ZnGA-Metal chloride (ZnGA-M) composite catalysts. These catalysts were found to be highly active for the copolymerization of CO2 and propylene oxide. Among the different metal salts, the catalysts treated with ZnCl2 (ZnGA-Zn) and FeCl3 (ZnGA-Fe) exhibited ~38% and ~25% increased productivities, respectively, compared to untreated ZnGA catalysts. In addition, these surface-modified catalysts are capable of producing high-molecular-weight polymers; thus, this simple and industrially viable surface modification method is beneficial from an environmental and industrial perspective.

Relative reactivities of epoxide monomers during copolymerization with carbon dioxide

The copolymerization of CO 2 /propylene oxide (PO)/cyclohexene oxide (CHO) was carried out using a Zn-based heterogeneous catalyst, namely a supported multi-component zinc dicarboxylate. The monomer reactivity ratios of PO ( r P O ) to CHO ( r C H O ) were estimated using the Fineman-Ross and Kelen-Tudos graphical methods. The results showed that the r P O values were significantly higher than the corresponding r C H O values in all cases, indicating that the incorporation of CHO into the polymer was kinetically unfavorable. The influence of the reaction temperature and pressure on the monomer reactivity ratios was also discussed. It was found that raising either the reaction temperature or pressure led to an increase in r C H O . In contrast, r P O decreased upon increasing the reaction temperature, but exhibited a small fluctuation upon increasing the reaction pressure. • Fineman-Ross and Kelen-Tudos methods were used to determine monomer reactivity ratios during the terpolymerization of CHO, PO and CO 2 with supported multi-component zinc dicarboxylate catalyst. • The r P O values were higher than 2, and the r C H O values were less than 0.5, meaning that a kinetic preference for incorporation of PO in the polymer. • The influence of the reaction temperature and pressure on the monomer reactivity was discussed.

Ring-opening polymerization of epoxides and ring-opening copolymerization of CO2 with epoxides by a zinc amino-bis(phenolate) catalyst

A one-pot synthesis of poly(ether-co-carbonates) catalyzed by an amino-bis(phenolate) zinc catalyst [L]Zn2Et2(THF) 1 (where [H2L] = n-propylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol) has been developed. Ring-opening polymerization (ROP) of cyclohexene oxide (CHO) can be performed by 1 with and without addition of BnOH or PPNCl as co-catalysts. The ROP of CHO can be inhibited by CO2 pressurization, which leads to the formation of polycarbonate blocks, or presence of other epoxides, which leads to the formation of poly(ether-co-carbonate) containing carbonate linkages and ether linkages. Polycarbonate formation was observed at 1 bar CO2 giving 23% carbonate linkages at this pressure. At 20 bar CO2, 92% carbonate formation was achieved in the presence of limonene oxide (LO). Poly(ether-co-carbonates) from mixtures of epoxides could be synthesized by changes in reaction temperatures and pressures.

Nickel-catalyzed copolymerization of carbon dioxide with internal epoxides by di-nuclear bis(benzotriazole iminophenolate) complexes

We report the synthesis of structurally well-characterized di-nuclear nickel bis(benzotriazole iminophenolate) (BiIBTP) complexes containing diverse mono- or bi-dentate monoanionic coligands for the utilization of copolymerization of carbon dioxide (CO2) with internal epoxides. The molecular structures of complexes 1–3 can be ascribed to bimetallic nickel(II) species containing a hexadentate BiIBTP main ligand and two homo-coligands of pentafluorobenzoate, pentafluorophenolate or chloride, whereas 4 and 5 are BiIBTP-ligated di-nickel chloride analogues mixed with carboxylate coligands. Di-nickel complexes 1 and 3 supported by O2CC6F5 and Cl coligands were demonstrated to be efficient catalysts for alternating copolymerization of CO2 with cyclohexene oxide (CHO) to afford CO2-based poly(cyclohexene carbonate)s (PCHCs) with >99% carbonate repeated units. Particularly, di-Ni di-chloride complex 3 was capable of giving high activity with a turnover frequency of 688 h−1 for such copolymerization under the optimal conditions. Interestingly, di-Ni catalyst 1 enables us to produce the low molecular weight di-hydroxyl end-capped PCHCs with unimodal molecular weight distributions while commercially available CHO without further purification was used as the epoxide monomer. In addition to CO2-CHO copolymerization, bimetallic complex 1 was also found to effectively copolymerize CO2 with cyclopentene oxide, generating highly alternating poly(cyclopentene carbonate)s with molecular weights in a broad range. Kinetic studies of CO2/CHO copolymerization catalyzed by 1 were investigated using 1H NMR spectroscopy and revealed the first-order dependence for both catalyst 1 and CHO concentrations.

Co-Ni Cyanide Bi-Metal Catalysts: Copolymerization of Carbon Dioxide with Propylene Oxide and Chain Transfer Agents

Synthesis of copolymers from carbon dioxide (CO2) and epoxides is an important research direction as such processes utilize the abundant greenhouse gas and deliver useful products. Specifically, cooligomers of CO2 and propylene oxide (PO) with a non-alternating structure can be used for polyurethane preparation. They are synthesized by employing Zn-Co cyanide catalysts. The application of alternative metal cyanide complexes is interesting from scientific and practical points of view. The purpose of this work was to study the copolymerization of CO2 and PO in the presence of Co-Ni cyanide catalysts and chain transfer agents (CTAs) in order to obtain low molecular weight products. Three Co-Ni catalysts with different contents of complexing agents were synthesized, characterized by several analytical methods and applied for this reaction. The complex without complexing agents was chosen for detailed investigation. 1,6-Hexanediol proved to be a more preferred CTA than poly(propylene glycol) and adipic acid. An oligo(ethercarbonate) (Mn = 2560, PDI = 2.5, CO2 = 20 mol.%) capped with OH groups was synthesized with relatively high productivity (1320 gPO+CO2/gcat in 24 h) and characterized by matrix-assisted laser desorption/ionization (MALDI) MS and NMR methods. The main chain transfer routes during the cooligomerization were suggested on the basis of the research results.

Synthesis of Polycarbonate Block Terpolymers Using Robust Cobalt Catalyst Systems

This contribution reports an efficient approach for preparing polycarbonate block terpolymers by immortal stepwise copolymerization of CO2 with different epoxides in the presence of enol chain transfer, mediated by robust cobalt catalyst systems consisting of the fluorine substituted salenCo(III)NO3 or biphenol-linker bimetallic Co(III) complex in conjunction with an ionic cocatalyst, PPNX (PPN = bis(triphenylphosphine)iminium, X = NO3− or 2,4-dinitrophenoxide). Various polycarbonate block terpolymers were obtained in perfectly unimodal distribution of their molecular weights with narrow polydispersity. They all possessed only one broad glass transition temperature, which could be adjusted by altering the length of different polycarbonate segments.

Nonionic Aliphatic Polycarbonate Diblock Copolymers Based on CO2, 1,2-Butylene Oxide, and mPEG: Synthesis, Micellization, and Solubilization.

Carbon dioxide (CO2) is a renewable carbon source that is easily available in high purity and is utilized as a co-monomer in the direct ring-opening polymerization of epoxides to obtain aliphatic polycarbonates. In this work, degradable aliphatic polycarbonate diblock copolymers (mPEG- b-PBC) are synthesized via catalytic copolymerization of CO2 and 1,2-butylene oxide, starting from monomethoxy poly(ethylene glycol) (mPEG) as a chain transfer reagent. The polymerization proceeds at low temperatures and high CO2 pressure, utilizing the established binary catalytic system ( R, R)-Co(salen)Cl/[PPN]Cl. Amphiphilic nonionic diblock copolymers with varying PBC block lengths and hydrophilic-lipophilic balance values between 9 and 16 are synthesized. The polymers are characterized via NMR and Fourier transform infrared spectroscopies as well as size exclusion chromatography, exhibiting molecular weights ranging from 2400 to 4100 g mol-1 with narrow dispersities ( Đ = Mw/ Mn) from 1.07 to 1.18. Furthermore, the thermal properties, i.e., Tg, Tm, and Td, are determined. Surface tension measurements prove that the amphiphilic polymers form micelles above the critical micelle concentration, whereas small-angle neutron scattering shows that they are of nearly spherical shape. Adding small amounts of the synthesized mPEG- b-PBC polymers to different microemulsion systems, we found that the polymers were able to strongly increase the efficiency of medium-chain surfactants to solubilize polar oils.

Carboxylate Salts as Ideal Initiators for the Metal-Free Copolymerization of CO2 with Epoxides: Synthesis of Well-Defined Polycarbonates Diols and Polyols

Tetrabutylammonium carbonate (TBAC) which is obtained by treating CO2 with tetrabutylammonium hydroxide is shown to perform as an ideal difunctional initiator for the copolymerization of carbon dioxide (CO2) and propylene oxide (PO) in the presence of triethylborane (TEB). In this system, CO2 thus serves as the initiating moiety of its own copolymerization with epoxides when used in the form of a carbonate salt. Based on this remarkable result, mono-, tri-, and tetrafunctional ammonium carboxylate initiators and also other difunctional carboxylate initiators were synthesized and used for the synthesis of well-defined ω-hydroxyl-polycarbonates with linear and star structures. Well-defined telechelics, three- and four-armed star samples of molar mass varying from 1 kg/mol to 10 kg/mol, with around 95% carbonate content, were successfully synthesized. The structure of the obtained polycarbonate ω-polyols were characterized by 1H NMR, MALDI-TOF, and GPC. The terminal hydroxyl functionality of polycarbonate diol was further used for polycondensation with diisocyanates to afford polyurethanes. Finally, taking TBAC as an example, the recyclability of this ammonium-based initiator is demonstrated for the preparation of polycarbonate diols.

Multifunctional CO2‐switchable polymers for the flocculation of oil sands tailings

ABSTRACTA series of multifunctional homopolymer and copolymer of 2‐dimethylamino ethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAM) were designed and used to flocculate oil sands mature fine tailings (MFTs). Carbon dioxide (CO2) protonated the tertiary amine groups of P(DMAEMA) and P(DMAEMA–NIPAM) making their chains positively charged. The pH sensitivity of these polymers favored the flocculation of the negatively charged clays in MFT due to charge neutralization. Three different polymers, P(DMAEMA), P(NIPAM33–DMAEMA67), and P(NIPAM67–DMAEMA33) were synthesized via aqueous free‐radical polymerization and used to flocculate MFT in the presence of CO2. Experimentally, CO2 was introduced in the system in three different ways: (1) CO2 was first bubbled into polymer solution, then the polymer solution was added to MFT, (2) CO2 was first bubbled into MFT and then the CO2‐free polymer solution was added to MFT, and (3) both polymers and MFT were bubbled with CO2 separately, then mixed together. We compared the effects of the method of CO2 addition, copolymer composition, and polymer molecular weight on MFT flocculation performance. Our results indicate that CO2‐switchable polymers can be employed to enhance the dewatering of challenging wastewaters such as oil sands tailings. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47578.

Poly(Alkyl Glycidate Carbonate)s as Degradable Pressure‐Sensitive Adhesives

AbstractInsertion of CO2 into the polyacrylate backbone, forming poly(carbonate) analogues, provides an environmentally friendly and biocompatible alternative. The synthesis of five poly(carbonate) analogues of poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate) is described. The polymers are prepared using the salen cobalt(III) complex catalyzed copolymerization of CO2 and a derivatized oxirane. All the carbonate analogues possess higher glass‐transition temperatures (Tg=32 to −5 °C) than alkyl acrylates (Tg=10 to −50 °C), however, the carbonate analogues (Td≈230 °C) undergo thermal decomposition at lower temperatures than their acrylate counterparts (Td≈380 °C). The poly(alkyl carbonates) exhibit compositional‐dependent adhesivity. The poly(carbonate) analogues degrade into glycerol, alcohol, and CO2 in a time‐ and pH‐dependent manner with the rate of degradation accelerated at higher pH conditions, in contrast to poly(acrylate)s.

Poly(Alkyl Glycidate Carbonate)s as Degradable Pressure-Sensitive Adhesives.

Insertion of CO2 into the polyacrylate backbone, forming poly(carbonate) analogues, provides an environmentally friendly and biocompatible alternative. The synthesis of five poly(carbonate) analogues of poly(methyl acrylate), poly(ethyl acrylate), and poly(butyl acrylate) is described. The polymers are prepared using the salen cobalt(III) complex catalyzed copolymerization of CO2 and a derivatized oxirane. All the carbonate analogues possess higher glass-transition temperatures (Tg =32 to -5 °C) than alkyl acrylates (Tg =10 to -50 °C), however, the carbonate analogues (Td ≈230 °C) undergo thermal decomposition at lower temperatures than their acrylate counterparts (Td ≈380 °C). The poly(alkyl carbonates) exhibit compositional-dependent adhesivity. The poly(carbonate) analogues degrade into glycerol, alcohol, and CO2 in a time- and pH-dependent manner with the rate of degradation accelerated at higher pH conditions, in contrast to poly(acrylate)s.

Triethyl borane-regulated selective production of polycarbonates and cyclic carbonates for the coupling reaction of CO2 with epoxides

The copolymerization of CO2 and epoxides bearing phenyl group is achieved by the combination of Lewis bases and excess triethyl borane that decides the selectivity.

Rare-earth/zinc heterometallic complexes containing both alkoxy-amino-bis(phenolato) and chiral salen ligands: synthesis and catalytic application for copolymerization of CO2 with cyclohexene oxide.

Ten rare-earth/zinc heterometallic complexes containing both alkoxy-amino-bis(phenolato) and chiral salen ligands were synthesized from the reactions of alkoxy-amino-bis(phenolato) rare-earth complexes with chiral salen zinc complexes via ligand redistribution and THF disassociation. Six of them were characterized by single-crystal X-ray diffraction, which showed 6-coordinate rare-earth and 5-coordinate zinc centres in the complexes. A primary catalytic application of these heterometallic complexes was studied, and it was found that samarium/zinc and dysprosium/zinc heterometallic complexes are highly efficient catalysts for copolymerization of CO2 with cyclohexene oxide while the alkoxy-amino-bis(phenolato) samarium complex and chiral salen zinc complex show very low catalytic activity or no catalytic activity for this copolymerization.

Groups 1, 2 and Zn(II) Heterodinuclear Catalysts for Epoxide/CO2 Ring-Opening Copolymerization.

A series of heterodinuclear complexes are reported where both Zn(II) and a metal from Group 1 or 2 are chelated by a macrocyclic diphenolate-tetra-amine ligand. The complexes are characterized in the solid state, where relevant by single crystal X-ray crystallography and elemental analysis, and in solution, using NMR spectroscopy and mass spectrometry. The complex synthesis is achieved by reaction of the ligand with diethyl zinc to form the monozinc complex, in situ, followed by subsequent coordination of the second metal; this method enables heterodinuclear conversions >90% as determined by NMR spectroscopy. Alternatively, the same heterodinuclear complexes are accessed by reaction between the two homodinuclear complexes at elevated temperatures for extended periods. These findings suggest that most of the heterodinuclear complexes are the thermodynamic reaction products; the only exception is the Na(I)/Zn(II) complex which is unstable with respect to the homodinuclear counterparts. The catalytic activities and selectivity of the stable heterodinuclear complexes are compared, against each other and the relevant homodinuclear analogues, for the ring-opening copolymerization of CO2 and CHO. Nearly all the heterodinuclear complexes are less active than the dizinc analogues, but the Mg(II)/Zn(II) catalyst is more active. The co-ligand influences the product selectivity, with iodide ligands resulting in cyclic carbonate formation and carboxylate ligands giving a high selectivity for polycarbonate.

Alternating Copolymerization of CO2 and Cyclohexene Oxide by New Pyridylamidozinc(II) Catalysts

Five new Zn(II) complexes bearing pyridylamido ligands with different substituents at the pyridine and at the amido moieties were synthesized and evaluated as catalysts for the alternating copolyme...

Acid-mediated surface etching of a nano-sized metal-organic framework for improved reactivity in the fixation of CO2 into polymers

Engineering the surface of Metal-organic frameworks (MOFs) will afford to advantageously improve their performances in catalysis. A particular example of industrially applied MOF-based catalysis is the zinc glutarate (ZnGA) catalyzed copolymerization of CO2 with an epoxide. Herein, we demonstrate how the modification of the surface of ZnGA aids to enhance its productivity in fixing CO2 into poly(alkylene carbonates), and deliver an industrially viable procedure to prepare a nanosized, surface-etched ZnGA by systematically controlling the reaction conditions and by using a mild-HCl solution. This surface modified-ZnGA exhibits ∼83% increased productivity than the standard-ZnGA and thus could be readily applicable in industries.

Carbon Dioxide–Derived Poly(propylene carbonate) as a Matrix for Composites and Nanocomposites: Performances and Applications

AbstractThe conversion of CO2 into polymers such as poly(propylene carbonate) (PPC) can contribute to the reduction of dependence on fossil fuel resourced polymers. PPC is a polymer synthesized from the catalyzed copolymerization between CO2 and propylene oxide. The global demand for renewable and biodegradable polymers coupled with the recent success in catalysis for the copolymerization of CO2 with epoxides has paved the way for an increased interest and growth in PPC polymers. On the contrary, the extensive utilization of PPC in many applications is still challenging due to its poor thermal stability, mechanical strength, and dimensional stability. Thus, many research efforts currently focus on improving these limitations. On the other hand, polymer processing and application development efforts have continued to utilize the existing PPC. This article presents a comprehensive review of PPC polymer as a matrix component of polymer composites and nanocomposites. Progress in current research on PPC‐based material applications, including industrial packaging, electromagnetic shielding, energy storage, and biomedical applications are included. A critical review of the biodegradability, compostability, and overall sustainability of PPC is also conducted. Finally, challenges that limit the extensive use of such materials, and future research and development directions are highlighted.

Propylene oxide end-capping route to primary hydroxyl group dominated CO2-polyol

In the past decade, poly(carbonate ether)polyols, or CO2-polyols, have been synthesized by the copolymerization of CO2 and propylene oxide (PO) with a double metal cyanide (DMC) catalyst in the presence of various chain transfer agents. CO2-polyols show great potential use as substitutes for polyols derived from fossil feedstock in the polyurethane industry. Brookfield viscosity tests have revealed the importance of primary hydroxyl (1° OH) content in the reactivity of CO2-polyols; in particular, the low 1° OH content of CO2-polyols severely limits their application in foam materials. Incorporation of more carbonate linkages has proven to be only moderately efficient for preparing CO2-polyols with high 1° OH content, e.g., 19F NMR spectroscopy indicates that the 1° OH content of a CO2-polyol can increase from 13% to 39% when the carbonate content in the CO2-polyol is increased from 26.1% to 80.0%. In this study, the PO end-capping route was developed using a strong Lewis acid, such as tris(pentafluorophenyl)borane (FAB) as a catalyst, and a CO2-polyol with 1° OH content of 60% was synthesized.