Effect of supercritical CO₂ on the copolymerization behavior of cyclohexene oxide/CO₂ and copolymer properties with DMC/Salen‐Co(III) catalyst system

Abstract

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. The copolymerization of cyclohexene oxide (CHO) and carbon dioxide (CO 2 ) was carried out under supercritical CO 2 (scCO 2 ) conditions to afford poly (cyclohexene carbonate) (PCHC) in high yield. The scCO 2 provided not only the C1 feedstock but also proved to be a very efficient solvent and processing aid for this copolymerization system. Double metal cyanide (DMC) and salen-Co(III) catalysts were employed, demonstrating excellent CO 2 /CHO copolymerization with high yield and high selectivity. Surprisingly, our use of scCO 2 was found to significantly enhance the copolymerization efficiency and the quality of the final polymer product. Thermally stable and high molecular weight (MW) copolymers were successfully obtained. Optimization led to excellent catalyst yield (656 wt/ wt, polymer/catalyst) and selectivity (over 96% toward polycarbonate) that were significantly beyond what could be achieved in conventional solvents. Moreover, detailed thermal analyses demonstrated that the PCHC copolymer produced in scCO 2 exhibited higher glass transition temperatures (T g 114 8C) compared to polymer formed in dense phase CO 2 (T g 77 8C), and hence good thermal stability. Additionally, residual catalyst could be removed from the final polymer using scCO 2 , pointing toward a green method that avoids the use of conventional volatile organic-based solvents for both synthesis and work-up.

Synthesis and Characterization of Structurally Diverse Alkaline-Earth Salen Compounds for Subterranean Fluid Flow Tracking

“…Metal derivatives of salens, porphyrins, phthalocyanines, and other related multidentate ligands that meet the demanding deep underground system criteria (i.e., solubility, stability, dispersible) have been preliminarily investigated. Of the derivatives noted above, the metal-salen complexes came to the forefront because of the high thermal stabilities reported for this family of compounds. − Additionally, the facile syntheses of salen derivatives is attractive, since the ring substituents can be easily tailored to increase the solubility in the various underground fluids of interest (water vs hydrocarbon). Ligand modifications, especially to the electron-rich rings, and metal selection should result in distinguishable features via vibrational spectroscopy.…”

Fabrication and characterization of the ternary composite catalyst system of ZnGA/RET/DMC for the terpolymerization of CO2, propylene oxide and trimellitic anhydride

“…Meng et al applied a combinatorial catalyst of DMC/ZnGA to catalyze the copolymerization of propylene oxide and CO 2 , attaining the PPC with high M w and yield whose T g was 42.0 C. 24 At the same time, they found a Salen-Co(III)/DMC catalyst system as a highly effective catalyst for CO 2 and cyclohexene oxide copolymerization. 25 This catalyst displayed the best efficiency at a ratio of Salen-Co(III)/DMC ¼ 1 : 3, and the obtained PPC polycarbonate content was more than 90%.…”

“… 24 At the same time, they found a Salen-Co( iii )/DMC catalyst system as a highly effective catalyst for CO 2 and cyclohexene oxide copolymerization. 25 This catalyst displayed the best efficiency at a ratio of Salen-Co( iii )/DMC = 1 : 3, and the obtained PPC polycarbonate content was more than 90%.…”

Precipitation copolymerization of methyl methacrylate/meth‐acrylate acid in supercritical carbon dioxide

“…Supercritical carbon dioxide (ScCO 2 ) has been well known as an environmentally friendly alternative to traditional solvents because of its non-toxic, inexpensive and natural abundance benefits. 1 ScCO 2 as the polymerizing medium, can be used to produce the polymers, such as homopolymer/copolymers, [2][3][4] cross-linked polymers, 5,6 porous hydrogel-materials, 7 et al In ScCO 2 system, the polymerization of the most monomers can avoid the chain transfer to the solvents, and it is the advantage to synthesizing the polymers with high molecular weight. 8 In addition, the residue solvent or monomer can be removed completely by the extraction using ScCO 2 as the extracting agent.…”