Ring-Opening Co- and Terpolymerization of Epoxides, Cyclic Anhydrides, and l-Lactide Using Constrained Aluminum Inden Complexes

Abstract

Seven constrained aluminum inden complexes having different substituents and diamine backbones were developed for the ring-opening copolymerization (ROCOP) of epoxides and bulky cyclic anhydrides giving alternating polyesters with T g ranging from 49 to 226 °C. Among several catalyst/cocatalyst screenings, the aluminum inden complex having a rigid phenylene backbone coupled with 4-dimethylaminopyridine showed the best performance giving linear polyesters. In the case of cyclohexene oxide (CHO) and succinic anhydride (SA), the linear poly(CHO-alt-SA) could be transformed to cyclic polymer when the polymerization was left under prolonged reaction time to induce intramolecular transesterification. The kinetic studies of the ROCOP revealed a zeroth-order dependence on cyclic anhydride and a first-order dependence on epoxide and the catalyst. The catalysts can be extended efficiently to the one-pot CHO/PA/l-lactide terpolymerization giving uncommon tapered copolymers of poly(CHO-alt-PA) and PLA via switchable polymerization.

High-Activity and High-Selectivity Air-Stable Nickel and Copper Complexes for Copolymerization of Epoxides with Anhydrides

“…To gain further insight into the chemical compositions of the polyesters derived from anhydrides, NMR spectroscopy was employed. Figure S6–S9 presents the NMR spectra obtained for the corresponding polyesters, and the results are in good agreement with the observations in the literature . We also tested the efficiency of catalyst 1 in copolymerization at 110 °C, and the results are shown in Table .…”

“…Then, in the initiation step, CHO coordinates with the nickel ion of the catalyst (Int-2), which facilitates the nucleophilic ring-opening of CHO through another DMAP group to yield the intermediate (Int-3). Second, the obtained intermediate reacts with PA to yield polyester through the alternating copolymerization of PA and CHO (Int-4), as observed in previous mechanistic investigations of the same polymerization. ,− …”

“…Figure S6−S9 presents the NMR spectra obtained for the corresponding polyesters, and the results are in good agreement with the observations in the literature. 53 We also tested the efficiency of catalyst 1 in copolymerization at 110 °C, and the results are shown in Table 3 demonstrated high activity, as evidenced by the TOF values ranging from 60 to 450 h −1 . This indicates the catalyst's ability to efficiently catalyze the copolymerization reaction.…”

Alternating ring‐opening copolymerization of cyclic anhydrides and epoxides by zeolitic imidazolate framework‐67: A promising approach

“…Especially, the Schiff base metal complexes are able to catalyze ROCOP to obtain ideal results under mild condition due to the five-or six-coordinated structure formed by the N and O atoms with the transition metals. 22,[25][26][27][28][29] However, it is difficult to purify the polymers because of the residual metal catalysts, which limits the further application of the resulting polymers. In view of this, the development of heterogeneous catalysts with high catalytic activity and easy recovery has become a hot direction in the current research field.…”

Synthesis of ABx and ABxC poly(ester-ether) polymers: polymer sequences and effects of Bx and BxC units on thermal properties

“…Due to a wide range of epoxides and cyclic anhydrides, the resulting polymers could lead to many backbone structures, functions, and properties. [5][6][7][8][9][10][11][12] The initial development of catalytic systems for ROCOP of cyclic anhydrides and epoxides involved simple metal complexes such as metal alkoxides, 13,14 metal halides 15 and free amines 16 affording polyesters with various degrees of ether linkages. Later development has led to several highly efficient catalysts that provide perfectly alternating polyesters based on ligated metal complexes such as those of Al, Cr, Co, Fe, Zn, and Mg. 5,6,[17][18][19] Lewis-base cocatalysts are normally required in many catalytic systems for efficient ROCOP.…”