Ionic Liquid‐Assisted Depolymerization of Condensation Polymers: A Review

Abstract

Plastic pollution has become a primary environmental concern in recent years that affects not only the environment but also wildlife and human health. Developing new, alternative ways to reduce and recycle plastic waste is an important and pressing challenge for industries, given its significant impact on greenhouse gas emissions, resource efficiency improvement, and landfilling reduction. Currently, reuse and mechanical recycling are the most employed routes to exploit post‐consumer plastics, but they have their own limitations. Chemical recycling of plastic is a process that offers a sustainable solution to the growing plastic waste problem. But the depolymerization of condensation polymers poses a lot of challenges in chemical recycling. Ionic liquids (ILs) have recently emerged as depolymerization reagents offering various advancements in polymer recycling and waste management. This review assesses the different recycling conditions using ILs for different condensation polymers such as polyesters, polyamides, polycarbonates, and polyethylene terephthalate. It also explores the possibility of using ionic liquid as a catalyst influencing depolymerization efficiency. This review is intended to build on existing knowledge and inform further research in the area of sustainable polymer recycling.

Design of depolymerizable polymers toward a circular economy

“…It is anticipated that future catalyst development can lower the depolymerization temperatures, as Cantat and coworkers have already shown the feasibility of doing so with the application of hydrosilanes 195 along with numerous other studies. 24,29 Reactive distillation can be more easily adopted with the current industrial infrastructure. To top it off, the distilled products exhibit a high purity.…”

“…24,25 Catalysis and processes such as temperature-gradient thermolysis are paving the way for upcycling of polyolefins. 26–28 Investigations into different solvents, 29,30 and conditions to depolymerize vinyl polymers 31 are also among the forefront of recent progresses. Developing new polymers to replace current ones also have many challenges to be addressed, chief among them is finding materials that have comparable stability and mechanical performances to existing commodity polymers and achieving economic feasibility of scaling up.…”

Assessment of PET Depolymerization Processes for Circular Economy. 1. Thermodynamics, Chemistry, Purification, and Process Design

“…Chemical recycling of PET is a popular topic in the literature. Beginning with an excellent 1997 review by Paszun and Spychaj published in this journal, there have been dozens of academic reviews on this topic in the last 25 years, and we include representative ones in this article. − For the most part, these reviews focus on the reaction pathways, kinetics, catalysts, and other aspects related to the improvement of reaction rates and conversion and kinetic modeling and tend to cover the same information. There is little discussion on the thermophysical and thermodynamic properties, separation and purification sections, and process design.…”