ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Organic bases and protic acids as binary catalysts for ring-opening alternating copolymerization of epoxides and cycle anhydrides

Xingji Zhu and Xinhui Kou

State Key Laboratory Base of Eco-Chemical Engineering, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, China

E-mail: kouxinhui@qust.edu.cn

Received: 4 September 2021  Accepted: 10 November 2021

Abstract:

We disclose a metal-free catalyst system of organic bases/protic acids for effective fully alternating copolymerization of cyclohexene oxide and phthalic anhydride. A series of commercial organic bases and protic acids were employed as binary catalysts, and the effects of different kinds and ratios of organic bases and protic acids were performed to find optimal conditions for achieving the highest catalytic performance. And our results indicated that DMAP/DPP showed higher activity (TOF = 574 h⁻¹ at 140 °C) and perfectly alternating selectivity (ester > 99%), producing polymers with narrow polydispersity (Ð = 1.08 ~ 1.22). Moreover, analysis of the resultant polymers was confirmed by GPC, NMR spectra and MALDI-TOF MS techniques which revealed that P(PA-alt-CHO) polyester with well-defined alternating structure without formation of polyether and DMAP can act as an initiator in DMAP/DPP catalyst system, resulting more effective ring-opening alternating copolymerization. However, trace amount of phthalic acid as an impurity in the system also acted as a bifunctional initiator influencing the molecular weight of the polymer. In addition, the DMAP/DPP catalytic system remained stable at high temperature and the development of this simple catalytic process provided a new chance to exploit in organocatalyzed polymerization.

Keywords: Ring-opening alternating copolymerization; Polyesters; Organic bases; Protic acids

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01980-6

Chemical Papers 76 (4) 2145–2152 (2022)