Jincai Wu
Hsuan-Ying Chen
Pimpa Hormnirun- 1State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, China
- 2Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, Taiwan
- 3Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan
- 4Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
- 5Department of Chemistry, Kasetsart University, Bangkok, Thailand
Editorial on the Research Topic
Advanced Catalysts in Ring-Opening Polymerization of Cyclic Esters
Now lots of biodegradable polymers were produced to replace the petroleum-based plastics to solve the environmental pollution. Herein, the scientists designed and synthesized the effective catalysts for the ring-opening polymerization (ROP) of cyclic esters, such as o-carboxyanhydrides, ε-caprolactone (CL), β-butyrolactone (BBL), ε-decalactone (DL), and lactide (LA). The catalysts for the ROP of o-carboxyanhydrides were explored in the review by Zhong and Tong. The ligands are essential for enhancing the catalytic activity and the selectivity control of catalysts. A study of CL polymerization by using Al complexes as catalysts reported by Zou et al. revealed that Al complexes bearing biphenolate phosphinoxide had higher catalytic activity of CL and rac-LA ROP than those bearing amino-bridged and phosphine-bridged biphenolates. The Zn complexes bearing amido-pyridinates reported by Chen et al. revealed that Zn complex with chelating dimethyl amino group could be tolerated in tetrahydrofuran during CL polymerization and exhibited greater catalytic activity than that with chelating pyridinyl group. The rac-LA polymerization mediated by urea/potassium alkoxide system reported by Kan et al. showed that urea/potassium alkoxide system had very high catalytic activity (90% conversion, 1–2 min), and produced PLAs with high Pi values (Pi = 0.83–0.93) and narrow Mw/Mn values (1.05–1.09). Studies of BBL and DL copolymerizations employing (salan) yttrium catalysts reported by Kiriratnikom et al. revealed that the syndiotactic-enriched poly(3-hydroxybutyrate)s blocks copolymers were produced. Finally, a special case reported by Lu et al. revealed that the phenoxyl oxygen of the catalyst attracked the α-hydrogen of the LA to produce the weaken H-O bond, and the benzyl alcohol initiated LA directly without replacing the ethyl group of the Zn complex.
The Research Topic of Advanced Catalysts in Ring-Opening Polymerization of Cyclic Esters provides knowledge on how the ligands affect the catalytic activity of the catalysts and a new possible mechanism of ROP. It is useful information for the scientists to design more effective catalysts for ROP of cyclic esters.
Author Contributions
All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.
Funding
H-YC is supported by the Ministry of Science and Technology of Taiwan (Grant MOST 107-2113-M-037-001) and Kaohsiung Medical University NSYSU-KMU JOINT RESEARCH PROJECT (NSYSUKMU 107-P010). JW is supported by National Natural Science Foundation of China (No. 21671087). PH is supported by Kasetsart University Research and Development Institute (KURDI) (No. 105.60) and National Research Council of Thailand (NRCT).
Conflict of Interest Statement
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Keywords: ring-opening polymerization, cyclic esters, caprolactone (CL), lactide, O-carboxyanhydrides, butyrolactone, decalactone
Citation: Wu J, Chen H-Y and Hormnirun P (2019) Editorial: Advanced Catalysts in Ring-Opening Polymerization of Cyclic Esters. Front. Chem. 7:404. doi: 10.3389/fchem.2019.00404
Received: 13 May 2019; Accepted: 20 May 2019;
Published: 04 June 2019.
Edited and reviewed by: Bunsho Ohtani, Hokkaido University, Japan
Copyright © 2019 Wu, Chen and Hormnirun. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Hsuan-Ying Chen, hchen@kmu.edu.tw; Pimpa Hormnirun, fscipph@ku.ac.th