Sequence‐Controlled Alternating Copolyesters Synthesis via Selective Ring‐Opening Polymerization

Abstract

The hydrolysis behavior of copolyester is significantly affected by its sequence structure. The crystallinity and melting-transition temperature of sequence-controlled copolyesters also may be different to random copolyesters. Therefore sequence-controlled copolyesters have become an attractive class of materials recently. Through living ring-opening polymerization (ROP), both the molecular weight and sequence structure of copolyesters can be easily controlled. In the past decades, the development of metal-based initiators has greatly promoted research in this field. In this minor review, the recent progress in the ROP of lactones initiated by metal complexes to synthesize copolyesters with a clear sequence structure is summarized. Moreover, the future development of sequence-controlled copolyester synthesis will be discussed.

Stereoselective Ring-Opening Polymerization of Lactones with a Fused Ring Leading to Semicrystalline Polyesters

“…Ring-opening polymerization (ROP) of cyclic esters has been widely employed for the preparation of functional PCLs due to the high-level control over the molecular weights, the dispersity, and even the stereochemistry of the resulting polymer. , The discovery that single-site metal complexes can exhibit both excellent ROP catalytic activity and controllable stereoselectivity led to a major paradigm shift in ROP catalysis. − Currently, many metal catalysts, such as tetradentate amino-bisphenolate complexes, − salen yttrium complexes, − and β-diiminate zinc complexes − have been reported to show moderate to excellent stereoselectivity for ROP of cyclic monomers. ,, Because the stereostructure in polymers significantly impacts their chemical and physical properties, the precise control over the microstructure of polymers would provide the access to valuable materials with desired properties.…”

Novel epoxide-promoted polymerization of lactides mediated by a zinc guanidine complex: a potential strategy for the tin-free PLA industry

“…All 1 H NMR and 13 C NMR spectra were recorded on a JEOL-400YH spectrometer at a frequency of 400 MHz. The obtained spectra were referenced to the signal of a residual trace of the partially protonated solvents for 1 H NMR [δ = 7.26 ppm (CDCl 3 )] and the solvents for 13 C NMR [δ = 77.1 ppm (CDCl 3 )].…”

“…All 1 H NMR and 13 C NMR spectra were recorded on a JEOL-400YH spectrometer at a frequency of 400 MHz. The obtained spectra were referenced to the signal of a residual trace of the partially protonated solvents for 1 H NMR [δ = 7.26 ppm (CDCl 3 )] and the solvents for 13 C NMR [δ = 77.1 ppm (CDCl 3 )]. The molecular weight (M n ) and dispersity value (Đ) of the polymer were determined by gel permeation chromatography (GPC) on a Waters 2414 binary system with a refractive index detector, calibrated with polystyrene standards.…”

“…8 To eliminate the requirement for tin complexes, many efforts have been made. [9][10][11][12][13][14][15] In terms of that, many metal complexes, such as Mg, 16,17 Al, [18][19][20] Zn, [21][22][23][24][25][26] and Fe, [27][28][29] have been successfully developed as environmentallyfriendly catalysts for the preparation of well-defined polymers via the ring-opening polymerization (ROP) of lactides. However, the majority of them still struggle to produce high molecular-weight polylactides effectively under industrial production conditions.…”

Sequence-Controlled Copolymerization of Salicylic O-Carboxyanhydrides by Organocatalysts

“…A significant challenge in polymer chemistry revolves around achieving polymerizations from a mixed monomer feedstock in one pot and exercising the chemoselective control over the incorporation of the monomers, instead of a sequential addition of monomers, to regulate the polymer structure and consequently the thermal and mechanical properties. , The exploration of selective transformations utilizing monomer mixtures, yielding polymers with homogeneous compositions spanning from random to block sequences, is highly desirable for improving chemical complexity. , Living polymerizations is required due to their ability to produce well-defined polymers. − When monomers are copolymerized simultaneously through a “living” mechanism, the relative reactivities of these monomers, which are precisely measured from homopolymerization experiments, are employed to accurately predict the copolymer sequence. This kinetic control is considered an effective strategy for regulating polymer composition in mixtures, particularly within a common polymerization method used. − …”