Epoxide + CO₂
→ aliphatic polycarbonates. Cyclohexene oxide with CO₂ gives poly(cyclohexene carbonate), PCHC.
Ring-Opening Copolymerization
ROCOP: turning CO₂ into polymer.
Carbon dioxide is an abundant, non-toxic and renewable C1 feedstock. Copolymerized with an epoxide, it becomes the backbone of an aliphatic polycarbonate — carbon that stays out of the atmosphere and does useful work.
The reaction
In ring-opening copolymerization, an epoxide and a second monomer are enchained alternately. Two families matter to us:
Epoxide + cyclic anhydride
→ fully alternating polyesters, giving access to backbones that ROP alone cannot reach.
The competing reaction — formation of the five-membered cyclic carbonate instead of polymer — is what a good catalyst has to suppress. Selectivity, not just activity, is the design target.
Our contribution
Chiral main-group catalysts.
Proline-derived Zn(II) and alkyl Al(III) compounds for efficient and controlled ROCOP of cyclohexene oxide with cyclic anhydrides.
Organocatalytic routes.
A simple organocatalyst for the ROCOP of epoxide and CO₂ to aliphatic polycarbonates — the subject of a granted Indian patent.
Bimetallic systems.
Binuclear Co, Ni, Cu and Zn complexes bearing bis-benzoxazole phenoxide ligands.
Unsymmetrical phenoxy-imine scaffolds.
Zn(II), Al(III) and Mg(II) compounds giving tacticity control in ROP and activity in ROCOP of epoxides with CO₂.
From the bench
Watch the chemistry happen.
PCHC synthesis
Poly(cyclohexene carbonate) formed by the ring-opening copolymerization of cyclohexene oxide with carbon dioxide — the reaction at the center of our CO₂ utilization work.
Recorded in the group's laboratory at the Department of Chemistry, IIT Madras.
Selected publications
ROCOP and CO₂ in our published work.
14 of 124 papers touching copolymerization, CO₂ utilization and polycarbonates.
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124
Ruthenium based organometallic catalysts for CO₂ hydrogenation: a decade update
Inorg. Chim.Acta 2026, 597, 123154.
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123
Chiral Proline-derived Zn(II) Complexes as Catalysts for Ring-Opening Polymerization and Ring-Opening Copolymerization Reactions
Polym. Chem. 2026, 17, 758-769.
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122
Efficient and Controlled Ring-Opening Copolymerization of Cyclohexene Oxide with Cyclic Anhydrides Catalyzed by Proline-based Chiral Alkyl Al(III) Compounds
Faraday Discuss, 2026, 262, 191–211.
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121
Salen Derivatives of Zr(IV) as Efficient Catalysts for the Ring-Opening Copolymerization of Epoxides with Anhydrides
Eur. J. Inorg Chem. 2026, 0, e202500510.
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120
Isolation and characterization of carbene supported air stable Co(II)-radical complexes with bileptic redox non-innocent ligands: stability, bonding, ring-opening copolymerization studies and photo-catalytic ring cyclization activity
Dalton Trans. 2025, 54, 11182–11192.
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118
Mononuclear and dinuclear tetravalent zirconium compounds as catalysts for the synthesis of aliphatic polyesters and aliphatic polycarbonates
Polymer 2025, 329, 128496.
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116
Mononuclear phenoxy-imine Mg(II) compounds as catalysts for the ring-opening copolymerization of epoxides with CO₂
Mater. Today Chem. 2024, 41, 102330.
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115
Phenoxy-imine supported hexacoordinate tetravalent titanium compounds: Synthesis, characterization and catalytic applications for ROP and ROCOP reactions
Eur. Polym. J. 2024, 216, 113281.
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113
Group 13 metal compounds as catalyst for the homopolymerization of epoxides
J. Polym. Res. 2024, 31, 14-21.
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110
Bimetallic Al(III) compounds as catalysts for the synthesis of biodegradable polyesters and polycarbonates
Eur. J. Org. Chem. 2023, 26, e202300371.
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108
Ring-opening copolymerization of CO₂ with epoxides catalyzed by binary catalysts containing half salen aluminum compounds and quaternary phosphonium salt
Mol. Catal. 2023, 540, 113053-113066.
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105
Iodine and alkali metal alkoxides: A simple and versatile catalyst system for fully alternating polyesters synthesis from phthalic anhydride and epoxides
Polym. Chem. 2022, 13, 4684-4691.
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99
Co2O3 and MnO2 as inexpensive catalysts for the ring‑opening polymerization of cyclic esters
J. Polym. Res. 2021, 28, 52-60.
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95
Metal-free Lewis pair catalyst synergy for fully alternating copolymerization of norbornene anhydride and epoxides: Biocompatible tests for derived polymers
Mater. Today Commun. 2019, 19, 306-314.
Interested in CO₂ utilization?
We collaborate with academic and industrial partners on carbon utilization and polycarbonate process development.