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

Embargo End Date
2020-11-21

Type
Article

Authors
Jia, Mingchen
Hadjichristidis, Nikos
Gnanou, Yves
Feng, Xiaoshuang

KAUST Department
Academic Affairs
Chemical Science Program
KAUST Catalysis Center (KCC)
Office of the VP
Physical Science and Engineering (PSE) Division
Polymer Synthesis Laboratory

KAUST Grant Number
BAS/1/1374-01-01

Online Publication Date
2019-11-21

Print Publication Date
2019-12-17

Date
2019-11-21

Abstract
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).

Citation
Jia, M., Hadjichristidis, N., Gnanou, Y., & Feng, X. (2019). Monomodal Ultrahigh-Molar-Mass Polycarbonate Homopolymers and Diblock Copolymers by Anionic Copolymerization of Epoxides with CO2. ACS Macro Letters, 1594–1598. doi:10.1021/acsmacrolett.9b00854

Acknowledgements
This research work is supported by KAUST under baseline funding (BAS/1/1374-01-01).

Publisher
American Chemical Society (ACS)

Journal
ACS Macro Letters

DOI
10.1021/acsmacrolett.9b00854

Additional Links
https://pubs.acs.org/doi/10.1021/acsmacrolett.9b00854

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