Temporal and spatial evolution of enzymatic degradation of amorphous PET plastics

Abstract

Biocatalytic degradation is an emerging strategy aiming for energy-efficient recycling of poly(ethylene terephthalate) (PET), the most commonly used thermoplastic polyester. Besides material composition and physico-chemical parameters, the degradation kinetics is co-determined by the evolving nanotopography. In this study, the 3-dimensional development of the surface characteristics of an amorphous PET film, reacted with a highly effective hydrolase enzyme for up to 24 h, was explored by vertical scanning interferometry and confocal microscopy. The spatio-temporal analysis unveiled that the degradation process is not uniform with respect to reaction time and spatial reactivity distribution. An early phase of an unspecific roughness evolution is followed by an advanced phase characterized by a circular degradation pattern, consisting of shallow pits that are steadily renewed over time. The data suggest a hindrance of degradation during the initial roughening process, demonstrating the potential role of targeted surface modification in the large-scale treatment of plastic waste.

Towards Sustainable Recycling of Epoxy-Based Polymers: Approaches and Challenges of Epoxy Biodegradation

“…There have been a few studies suggesting that some microorganisms might be capable of degrading epoxy, but unambiguous proof about the involved enzymes is still not available. In this regard, the high durability and cross-linked structure of epoxy resins are significant hurdles in the biochemical degradation process, as the materials are insoluble in aqueous reaction systems, reducing accessibility for biocatalysts [ 118 ]. Moreover, their hydrophobic nature and high molecular weight further limits the attachment of microbial biofilms and might hinder the targeted action of an enzyme [ 83 , 119 ].…”

Thermally Stable Biodegradable Polyesters with Camphor and Tartaric Acid Coupled Cyclic Diester Monomers for Controlled Hydrolytic Degradations

“…6−8 However, due to their exceptional stability, they barely decompose in the natural environment and their lifetimes can be extended to 10−100 years. 9,10 Recently, enzymeassisted biodegradations with various types of PET hydrolases, such as esterases, lipases, and cutinases, have been extensively studied. 11−14 Specifically, enzymatic degradations with leafbranch compost cutinases were enabled to depolymerize 90% of the PET waste in 10 h at 72 °C.…”

“…Developing biodegradable polymers without sacrificing high-performance material properties is one of the most demanding and difficult issues facing eco-friendly plastics industries. − Due to their superior mechanical, thermal, and optical properties, polyesters have been widely utilized for industrial applications. , Terephthalate-based polyesters, such as poly­(ethylene terephthalate) (PET), poly­(butylene terephthalate) (PBT), and poly­(hexylene terephthalate) (PHT), are examples of engineering plastics with high thermal stability, exhibiting degradation temperatures ( T d ) of >400 °C, with variable glass transition temperatures ( T g ) from 10–80 °C that are dependent on alkyl chain lengths in the monomers. − However, due to their exceptional stability, they barely decompose in the natural environment and their lifetimes can be extended to 10–100 years. , Recently, enzyme-assisted biodegradations with various types of PET hydrolases, such as esterases, lipases, and cutinases, have been extensively studied. − Specifically, enzymatic degradations with leaf-branch compost cutinases were enabled to depolymerize 90% of the PET waste in 10 h at 72 °C . However, these approaches still need improvements for wide applications due to the lack of degradation capabilities for highly crystalline polyesters .…”

Biodegradation of materials: building bridges between scientific disciplines

“…1, although the topics that mobilize the largest communities have started to spread across various scientific disciplines (see the case of "biofouling", which widely impacts all six disciplines involved in the study of materials biodegradation, except for the Earth sciences), others can still be considered as niches, which hardly spread beyond the frontiers of their very specific communities (e.g., bioerosion and bioweathering are almost exclusively restricted to the fields of Earth and life sciences). Interestingly, the term biodegradation itself is now almost exclusively restricted to the breakdown of polymeric substances mediated by living organisms 3,4 , a concern of the utmost importance in a world where 79% of plastic ends up in the environment.…”