Successfully interfacing enzymes and biomachinery with polymers affords on-demand modification and/or programmable degradation during the manufacture, utilization and disposal of plastics, but ...requires controlled biocatalysis in solid matrices with macromolecular substrates
. Embedding enzyme microparticles speeds up polyester degradation, but compromises host properties and unintentionally accelerates the formation of microplastics with partial polymer degradation
. Here we show that by nanoscopically dispersing enzymes with deep active sites, semi-crystalline polyesters can be degraded primarily via chain-end-mediated processive depolymerization with programmable latency and material integrity, akin to polyadenylation-induced messenger RNA decay
. It is also feasible to achieve processivity with enzymes that have surface-exposed active sites by engineering enzyme-protectant-polymer complexes. Poly(caprolactone) and poly(lactic acid) containing less than 2 weight per cent enzymes are depolymerized in days, with up to 98 per cent polymer-to-small-molecule conversion in standard soil composts and household tap water, completely eliminating current needs to separate and landfill their products in compost facilities. Furthermore, oxidases embedded in polyolefins retain their activities. However, hydrocarbon polymers do not closely associate with enzymes, as their polyester counterparts do, and the reactive radicals that are generated cannot chemically modify the macromolecular host. This study provides molecular guidance towards enzyme-polymer pairing and the selection of enzyme protectants to modulate substrate selectivity and optimize biocatalytic pathways. The results also highlight the need for in-depth research in solid-state enzymology, especially in multi-step enzymatic cascades, to tackle chemically dormant substrates without creating secondary environmental contamination and/or biosafety concerns.
Polylactide and polycaprolactone are both biodegradable polymers produced through metal‐catalyzed ring‐opening polymerization. For a truly sustainable lifecycle of these polymers it is essential to ...replace the industrially used cytotoxic catalyst tin(II) bis(2‐ethylhexanoate) Sn(Oct)2 with non‐toxic alternatives. Here, we report the fastest known robust catalyst in the polymerization of lactide and ϵ‐caprolactone. This zinc guanidine catalyst can polymerize non‐purified technical rac‐lactide and ϵ‐caprolactone in the melt at different M/I ratios with fast rate constants, high molar masses, and high yields in a short time, leading to colorless, transparent polymer. Moreover, we report that polylactide and polycaprolactone produced by zinc‐guanidine complexes have favorably high crystallinities. In fact, the obtained polylactide shows a more robust degradation profile than its Sn(Oct)2‐catalysed equivalent due to a higher degree of crystallinity.
A highly active and robust zinc guanidine catalyst for the polymerization of lactide and ϵ‐caprolactone was investigated. The catalyst not only has a faster catalytic activity in bulk for the ring‐opening polymerization of lactide than the industrially used Sn(Oct)2 catalyst but also leads to a higher degree of crystallinity in the polymer then Sn(Oct)2, progressing towards a more robust degradation profile.
Biodegradable plastics (BPs) have attracted much attention since more than a decade because they can easily be degraded by microorganisms in the environment. The development of aliphatic-aromatic ...co-polyesters has combined excellent mechanical properties with biodegradability and an ideal replacement for the conventional nondegradable thermoplastics. The microorganisms degrading these polyesters are widely distributed in various environments. Although various aliphatic, aromatic, and aliphatic-aromatic co-polyester-degrading microorganisms and their enzymes have been studied and characterized, there are still many groups of microorganisms and enzymes with varying properties awaiting various applications. In this review, we have reported some new microorganisms and their enzymes which could degrade various aliphatic, aromatic, as well as aliphatic-aromatic co-polyesters like poly(butylene succinate) (PBS), poly(butylene succinate)-co-(butylene adipate) (PBSA), poly(ε-caprolactone) (PCL), poly(ethylene succinate) (PES), poly(L-lactic acid) (PLA), poly(3-hydroxybutyrate) and poly(3-hydoxybutyrate-co-3-hydroxyvalterate) (PHB/PHBV), poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(butylene adipate-co-terephthalate (PBAT), poly(butylene succinate-co-terephthalate) (PBST), and poly(butylene succinate/terephthalate/isophthalate)-co-(lactate) (PBSTIL). The mechanism of degradation of aliphatic as well as aliphatic-aromatic co-polyesters has also been discussed. The degradation ability of microorganisms against various polyesters might be useful for the treatment and recycling of biodegradable wastes or bioremediation of the polyester-contaminated environments.
In order to utilize biodegradable polymers as a functional material, it is important to make the best use of their biodegradability. Biodegradation of aliphatic polyesters, such as PCL, PBSA and ...P3HB, in seawater was investigated. BOD test using seawater and field test were carried out. As for BOD test, several factors were investigated such as tide, preservation of seawater, sampling place, population of microorganism, and seawater temperature. Biosynthesized P3HB and PHBHH showed rapid biodegradation by BOD method. As for synthetic polyesters, PCL also degraded fast. However, PBSA which is a popular biodegradable polymer in soil was not always biodegraded by BOD method with seawater. PBS and PBAT showed much slow biodegradation. Solvent cast films were immersed in the sea at a depth of 1.5 m. After 4 weeks, the weight loss of P3HB film was about 90%. On the contrary, the biodegradation by BOD method for 4 weeks was around 50%. Synthetic polyesters also showed obvious weight loss in field test, in contrast to the BOD results.
•Marine biodegradation of various polyesters were examined by BOD method and Field test.•Some synthetic polymers did not show obvious biodegradation by BOD test in spite that they were biodegraded well in the sea.•BOD test is a useful method to examine factors effected on biodegradation.
Phosphorus-containing flame retardants synthesized from renewable resources have had a lot of impact in recent years. This article outlines the synthesis, characterization and evaluation of these ...compounds in polyesters and epoxy resins. The different approaches used in producing biobased flame retardant polyesters and epoxy resins are reported. While for the polyesters biomass derived compounds usually are phosphorylated and melt blended with the polymer, biobased flame retardants for epoxy resins are directly incorporated into the polymer structure by a using a phosphorylated biobased monomer or curing agent. Evaluating the efficiency of the flame retardant composites is done by discussing results obtained from UL94 vertical burning, limiting oxygen index (LOI) and cone calorimetry tests. The review ends with an outlook on future development trends of biobased flame retardant systems for polyesters and epoxy resins.
The synthesis and aqueous self‐assembly of a new class of amphiphilic aliphatic polyesters are presented. These AB block polyesters comprise polycaprolactone (hydrophobe) and an alternating polyester ...from succinic acid and an ether‐substituted epoxide (hydrophile). They self‐assemble into biodegradable polymersomes capable of entering cells. Their degradation products are bioactive, giving rise to differentiated cellular responses inducing stromal cell proliferation and macrophage apoptosis. Both effects emerge only when the copolymers enter cells as polymersomes and their magnitudes are size dependent.
Class act: The synthesis and aqueous self‐assembly of a new class of amphiphilic aliphatic polyesters are presented. They self‐assemble into biodegradable polymersomes capable of entering cells. Their degradation products are bioactive, giving rise to differentiated cellular responses inducing stromal cell proliferation and macrophage apoptosis. Both effects emerge only when the copolymers enter cells as polymersomes.
Polyester elastomers are soft, biodegradable and biocompatible and are commonly used in various biomedical applications, especially in tissue engineering. These synthetic polyesters can be easily ...fabricated using various techniques such as solvent casting, particle leaching, molding, electrospinning, 3-dimensional printing, photolithography, microablation
etc.
A large proportion of tissue engineering research efforts have focused on the use of allografts, decellularized animal scaffolds or other biological materials as scaffolds, but they face the major concern of triggering immunological responses from the host, on top of other issues. This review paper will introduce the recent developments in elastomeric polyesters, their synthesis and fabrication techniques, as well as their application in the biomedical field, focusing primarily on tissue engineering in ophthalmology, cardiac and vascular systems. Some of the commercial and near-commercial polyesters used in these tissue engineering fields will also be described.
Polyester elastomers are soft, biodegradable and biocompatible and are commonly used in various biomedical applications, especially in tissue engineering.
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•1,4:3,6-dianhydrohexitols (isosorbide, isomannide and isoidide) are rigid, biobased diols.•They impart favorable thermal and mechanical properties.•Low reactivity exacerbates the ...synthesis of high molecular weight polyesters.
Plastic materials play a pivotal role in modern society. Finding sustainable alternatives to established fossil-based polymers is an important part of the effort to reduce the environmental impact of the materials sector. 1,4:3,6-dianhydrohexitols (isosorbide, isomannide and isoidide) are a group of biobased diol monomers that are promising for the synthesis of sustainable polyesters. Their rigid molecular structure imparts favorable material properties to polymers. Isosorbide is especially interesting due to its current commercial availability and synthesis from glucose. This potential is reflected in the large number of publications on polyesters with isosorbide in the past decade. Despite this, high molecular weight polyesters with high molar percentages of 1,4:3,6-dianhydrohexitols remain elusive due to the low reactivity of 1,4:3,6-dianhydrohexitols in (trans)esterification reactions. This review compares the efforts on the synthesis of polyesters with 1,4:3,6-dianhydrohexitols from both the academic and patent literature and puts them into perspective regarding industrial viability. Interesting synthesis strategies and possible future developments are highlighted together with material properties.
This review focuses on the polyesters such as polylactide and polyhydroxyalkonoates, as well as polyamides produced from renewable resources, which are currently among the most promising ...(bio)degradable polymers. Synthetic pathways, favourable properties and utilisation (most important applications) of these attractive polymer families are outlined. Environmental impact and in particular (bio)degradation of aliphatic polyesters, polyamides and related copolymer structures are described in view of the potential applications in various fields.
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