Alkali Metal Carboxylate as an Efficient and Simple Catalyst for Ring-Opening Polymerization of Cyclic Esters

Abstract

Alkali metal carboxylates were discovered as efficient and simple catalysts for the ring-opening polymerization of cyclic esters that are alternatives to conventional metal-based catalysts and organocatalysts. In our system using an alcohol initiator and this simple catalyst, biodegradable and biocompatible aliphatic polyesters, such as poly(lactide), poly(ε-caprolactone), poly(δ-valerolactone), and poly(trimethylene carbonate), were obtained with predictive molecular weights ranging from 3500 to 22 600 and narrow dispersities. A kinetic experiment for the ROP of L-lactide confirmed the controlled/living nature of the present ROP system, which allowed the precise synthesis of end-functionalized polyesters as well as multihydroxyl-containing polyesters, including α,ω-hydroxy telechelic and starshaped polyesters. Furthermore, a block copolymer containing the poly(L-lactide) segment was successfully synthesized using a macroinitiator possessing a hydroxyl group at the chain end. The tunability of the alkali metal carboxylates by the appropriate choice of the alkyl moiety and countercation enables not only control of the polymerization behavior but also expansion of the scope of the applicable monomers. Given the low cost, easy handling, and low toxicity of the alkali metal carboxylates, the present ROP system can be highly promising for both laboratory-and industrial-scale polyester productions.

Controlled Random Terpolymerization of β -Propiolactone, Epoxides, and CO 2 via Regioselective Lactone Ring Opening

“…The fast insertion of CO 2 into the Co-O bond prevented various side reactions, such as alkoxy chain end formation and subsequent intramolecular and/or intermolecular transesterification, as well as epoxide homopolymerization. Quantitative 13 C NMR analysis suggested that the terpolymers had junction unit contents of up to 40%. To the best of our knowledge, this is the only example of a statistical carbonate/ester terpolymer in which the two components are distributed in the polymeric backbone based on probability.…”

“…As an alternative to fermentative synthesis, PHB can also be produced by the catalytic ring-opening polymerization of β-butyrolactone, a low-cost and readily available feedstock generated from the carbonylation of epoxides [7][8][9][10] . Commonly, the nucleophilic ring opening of lactones occurs at the ester group through the cleavage of an acyl C(=O)-O bond, leading to the formation of alkoxy chain ends [11][12][13][14] . However, alkoxy chain ends can react with not only the ester groups of lactone monomers but also the ester groups of the resulting polyester backbone via intramolecular and/or intermolecular (a)).…”

“…Thus, to clarify the ring-opening position in BPL during terpolymerization, enantiopure (R)-PO (ee > 99%) was polymerized with BPL and CO 2 to produce a (R)-PO/CO 2 /BPL terpolymer. In comparison with a blend of (R)-PPC and poly(3-hydroxypropionate), the 1 H and 13 C NMR spectra of the (R)-PO/CO 2 /BPL terpolymer showed obvious splitting patterns for various chemical shifts (Supporting Information, Figure S10 and S11), indicating that the carbonate and ester components were Figure S12 in the Supporting Information shows the high-resolution 1 H- 13 This result indicated that the C c ′ and C d ′ atoms belong to junction units D and C, respectively. The quantitative 13 C NMR spectrum demonstrated that the junction unit content in the PO/CO 2 /BPL terpolymer was up to 40% (Figure 4).…”

Development of recoverable and recyclable Fe3O4‐supported organocatalysts for ring‐opening polymerization

“…TGA was used to evaluate the thermal stability of Fe 3 O 4 @PZS@HMP 1 catalysts. The initial decomposition starts at approximately 150 C, indicating that the catalysts remain thermal stable during the ROP process of δ-VL or ε-CL where the reaction is usually conducted at the temperature of 80-100 C. 58,59 The weight loss was reduced from 96.64% to 76.21% at the temperature range from 150 to 330 C, which is attributed to the decomposition of HMP 1 , and the decomposition of PZS occurred at 410 500 C (ESI †, Figure S2d).…”

Changes in the morphology of poly( l ‐lactide‐ ran ‐δ‐valerolactone) following supercritical carbon dioxide processing

“…For this reason, biodegradable polymers have been studied in detail and some are currently utilized in industrial processes and consumer goods. Biodegradable polymers can be categorized as those made from modified natural materials, biosynthesized using microorganisms, and chemically synthesized in conjunction with catalysis . The last category has attracted particular attention as it is associated with simple molecular designs, facile synthetic processes and inexpensive raw materials.…”