Recyclable/degradable materials via the insertion of labile/cleavable bonds using a comonomer approach

Polymers have many advantages such as low weight, low cost, and, importantly, stability under thermal, chemical, and mechanical stress. This stability, on the other hand, leads to criticism for causing environmental pollution on a macro-scale and via long-lasting microscopic plastic fragments (microplastics). Since it is very difficult but also very expensive to design brand-new materials that could both have the desired properties (mechanical, thermal, solvent resistance, etc.) and that are in the same time either recyclable and/or biodegradable, transforming already known materials to make them biodegradable/recyclable is more interesting. This approach relies on the introduction of labile/cleavable bonds onto the polymer backbone. The degradation could thus occur from these weak bonds leading to oligomers that could be easily recyclable and/or bioassimilable. This approach is currently applied to all polymerization techniques and led to interesting alternatives to numerous polymers ranging from polyolefins (polyethylene, polypropylene, …), polyethylene oxide, polyesters, polyamides, vinyl polymers, thermosets, etc. This review thus aimed at giving a comprehensive overview of the chemistries/monomers that could be used for the different polymerization processes but also described the alternatives to common polymers whatever the polymerization process. An emphasis will be put on the degradation/biodegradation/recycling properties of the new materials.