Block Poly(carbonate-ester) Ionomers as High-Performance and Recyclable Thermoplastic Elastomers

Thermoplastic elastomers based on polyesters/carbonates have the potential to maximize recyclability, degradability and renewable resource use. However, they often underperform and suffer from the familiar trade-off between strength and extensibility. Herein, we report well-defined reprocessable poly(ester-b-carbonate-b-ester) elastomers with impressive tensile strengths (60 MPa), elasticity (>800 %) and recovery (95 %). Plus, the ester/carbonate linkages are fully degradable and enable chemical recycling. The superior performances are attributed to three features: (1) Highly entangled soft segments; (2) Fully reversible strain-induced crystallization and (3) Precisely placed Zn^II -carboxylates dynamically crosslinking the hard domains. The one-pot synthesis couples controlled cyclic monomer ring-opening polymerization and alternating epoxide/anhydride ring-opening copolymerization. Efficient convresion to ionomers is achieved by reacting vinyl-epoxides to install Zn^II -carboxylates.

Biodegradable thermoplastic copolyester elastomers: Methyl branched PBAmT

A series of novel biodegradable copolyesters named poly(butylene 3-methyl adipate co-terephthalate) (PBAmT) were synthesized from the monomers of 3-methyl adipic acid (AAm), 1,4-butanediol (BDO), and terephthalic acid (TPA) through a process of esterification and polycondensation. 1H NMR analysis shows that they are random copolymers whose composition can be well controlled by the feed ratio of monomers. From the results of DSC and XRD, the introduction of methyl group successfully destroys the crystallizability of the PBAm chains, thus making it become a relative soft segment compared to PBA, while these random PBAmT copolymers constructed by soft segment PBAm and rigid segment PBT change from semi-crystalline polymers to nearly amorphous polymers as the feed ratio of Am increases. Especially, mechanical tests reveal that the copolymers show outstanding elasticity and rebound resilience with excellent strength. These thermoplastic copolyester elastomers with good performance by simply introduction of branched methyl group on polybutylene adipate terephthalate (PBAT) copolymer chains may well explore the potential application of biodegradable PBAT-based material.

Biodegradable all polyester-based multiblock copolymer elastomers with controlled properties

A cascade polymerization method is developed here for the synthesis of environmentally-friendly biodegradable all polyester-based thermoplastic elastomers with tunable properties.

Polyethylene-like materials from plant oils

Polyethylene (PE) is the most important synthetic polymer material produced. Its excellent material properties arise from crystalline interactions in its hydrocarbon chains. This simple concept inspires studies of materials based on alternative non-fossil feedstocks and with additional traits such as a non-persistent nature. Renewable seed oil or microalgae oil lipids can serve as a feedstock for long-chain difunctional monomers. Catalytic conversion of their unsaturated fatty acids by e.g. isomerizing carbonylation or olefin metathesis yields long-chain monomers X-(CH₂)_n-X with 18-26 carbon atoms and terminal dicarboxy, diol or diamine groups (X), and ultralong-chain PE telechelics with 48 carbon atoms. These can be polymerized to polyesters, polycarbonates and other (ultra)long-chain polycondensates. These in many cases possess PE-like solid-state structure and properties. Unlike PE, they contain in-chain functional groups that can potentially enhance degradability. The crystalline and hydrophobic nature of the polymers decelerates degradation strongly compared to rapidly degrading shorter chain analogues. Our preliminary findings suggest that a non-persistent nature can be achieved for these materials. This review article is based on a lecture held at the Royal Society Discussion Meeting on Science to enable the circular economy. This article is part of a discussion meeting issue 'Science to enable the circular economy'.

Convenient Controlled Aqueous C1 Synthesis of Long-Chain Aliphatic AB, AA, and BB Macromonomers for the Synthesis of Polyesters with Tunable Hydrocarbon Chain Segments

The insertion of long hydrocarbon chains between ester groups in polyester allows for introduction and modulation of crystallinity, which can result in enhanced performance approaching high-density polyethylene. We report a convenient synthesis of building blocks for long-chain aliphatic polyesters via an aqueous C1 polymerization. The macromonomers include ω-hydroxyacid esters, α,ω-diols and α,ω-diacids. The length of hydrocarbon chain segment (C20-C60) can be controlled by the ratio of monomer/initiator in the C1 polymerization. The obtained polyesters from condensation of the long-chain ω-hydroxyacid esters have thermal and mechanical properties indistinguishable from related materials derived from biomass.