Chemoselective and controlled ring-opening copolymerization of biorenewable α-methylene-δ-valerolactone with ε-caprolactone toward functional copolyesters

Self Cite

The large production and indiscriminate disposal of plastics have resulted in serious resource and global environmental crises, which has raised a demand to develop a more sustainable and circular plastics economy. An ideal strategy to address the end-of-life issue of plastics is to develop nextgeneration polymers with closed-loop life cycles, which can be selectively depolymerized back to monomers at the end of their service life. Aliphatic polyesters prepared by ring-opening polymerization (ROP) of moderately strained lactones have shown great potential in closed-loop recyclable polymers. This Perspective highlights the recent achievements for closed-loop recyclable polyesters that are derived from four-, five-, six-, and seven-membered lactones by focusing on the discussion of thermodynamic and kinetic considerations, monomer design principles and polymer preparations, material properties, and chemical recyclability. Finally, the current challenges and possible directions for closed-loop recyclable polymers are also discussed.

Section: Thermodynamic and Kinetic Considerationsmentioning

confidence: 99%

“…Ring-opening (co)polymerization of MVL as well as depolymerization and the physical properties of PMVL ROP . , …”

Section: Closed-loop Recyclable Polyestersmentioning

confidence: 99%

Ring-Opening Polymerization of Lactones to Prepare Closed-Loop Recyclable Polyesters

Li,

Shen,

2024

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“…The reactivity ratios of mixed monomers can be finely tuned by various stimuli, such as solvent, additives, and the chemical catalyst, − enabling the composition sequence along the chain to change from random to block copolymerization. Pioneering advancements in monomer sequence selectivity have been demonstrated in processes, including ring-opening copolymerization (ROCOP). − In the pursuit of advancing the eco-friendly nature, a multitude of organocatalytic systems have been explored for polymerization. − With significant accomplishments using organocatalysts, the synthesis of sequence-controlled (multi)block copolyesters has been achieved in one pot via ROCOP of epoxides, cyclic anhydrides, − and cyclic esters or O -carboxyanhydride (OCA) and epoxide mixtures. , However, when dealing with similar monomer mixtures, the lack of kinetic differentiation is preferred to generate random copolymerization of these mixed monomers. , To date, well-defined block copolyesters have been predominantly obtained through sequential monomer addition or utilizing a difunctional initiator. , The task of organocatalyzing similar monomer mixtures to access block sequences in a one-pot fashion remains a significant challenge.…”

Section: Introductionmentioning

confidence: 99%

Sequence-Controlled Copolymerization of Salicylic O-Carboxyanhydrides by Organocatalysts

Liang,

Yang

2024

The composition sequence of a copolymer is intricately linked to its physical and mechanical properties. However, achieving chemical selectivity for copolymerization monomers and controlling the sequence structure of copolymers remain a challenge. This study delves into a strategy that involves tuning the organocatalyst transition from hydrogen bonding interaction to ionic pair to realize copolymerization sequence control in one-pot reactions. Ring-opening copolymerization (ROCOP) of salicylic acid O-carboxyanhydride (SAOCA) and its analogous monomers, including 5-methylsalicylic acid Ocarboxyanhydride (5-MeSAOCA) and 4-fluor-salicylic acid Ocarboxyanhydride (4-FSAOCA), is successfully conducted in tetrahydrofuran (THF) at ambient conditions, resulting in narrow chain distributions (Đ < 1.25). This accomplishment is made possible by utilizing a catalytic combination of 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) and thioureas (TUs) with varying pK a values. The acidity of TU influences its interaction with DBU to generate the transition states of hydrogenbonding or ionic pair, while the quantity of TU affects the steric hindrance around the anion; both are crucial factors in regulating the sequence distribution of PSA-series copolymers ranging from random to block architecture.

Tackling the Thermodynamic Stability of Low-Ceiling Temperature Polymers for the Preparation of Tough and Chemically Recyclable Thermoplastic Polyurethane-Urea Elastomers

Meyersohn,

Block,

Bates

et al. 2024

Thermoplastic polyurethane-ureas (TPUUs) from biobased, depolymerizable polyesters are promising as high-value polymeric materials for a circular economy. We demonstrate the bulk room temperature polymerization of β-methyl-δ-valerolactone (βMVL) using HCl (as a solution in ether) as a simple acid catalyst to prepare low molar mass polyols. One of the key challenges of poly(β-methyl-δ-valerolactone) (PβMVL) is the non-negligible equilibrium monomer concentration ([M]eq) at room temperature and above. To mitigate the consequences of residual monomer that results from βMVL polymerization, we utilize strategies including (i) rapid distillation to rid the polymer of residual monomer, (ii) sequestration of remaining monomer with diamines to prepare diamidodiols in situ along with the polyol, which can subsequently be used directly as chain extenders in TPUU syntheses, or (iii) the copolymerization of βMVL with lactone monomers that exhibit a higher ceiling temperature to prepare copolymers with varying degrees of crystallinity, improved thermal stability, and reduced residual βMVL content. The aliphatic polyols can then be used as soft-segments in a one-pot approach to prepare TPUUs by reacting with isophorone diisocyanate and chain extending with water. The resulting TPUUs are tough, elastic materials that can be chemically recycled by depolymerization to βMVL, which can be used to prepare new TPUUs with comparable properties.