This review highlights the promising strategies developed to break down polycondensate polymers back to monomers using chemicals and enzymes. Our aim is to create a renewed awareness to valorize plastic waste into virgin plastics.

Cyclomatrix polyphosphazene films have been synthesized by interfacial polymerization of hexachlorocyclotriphosphazene with a variety of biphenols.

Poly­(ethylene furanoate) (PEF) is widely advocated as a renewable alternative to the fossil-based polyester poly­(ethylene terephthalate) (PET). Whereas the UV stability of PET is well-studied, little is known for PEF. Here, we compare the UV stability of both polyesters after 500 h of UV irradiation in a Q-SUN xenon arc chamber. Both the virgin and irradiated polyesters were characterized by FTIR, SEC, DSC, NMR, TGA, and MALDI-TOF MS. PET showed only minor signs of degradation under the applied test conditions, while PEF showed significant discoloration as well as evidence of both cross linking/chain extension and chain scission. Also, the thermal properties and the ability to crystallize of PEF were severely impacted by UV irradiation. Although a detailed study on the degradation mechanism is out of the scope of this work, we found indications that Norrish type I and II degradation reactions play an important role in the UV degradation of PEF.

Membrane separation under harsh conditions, such as high-p,T or in the presence of aggressive chemicals, requires a robust membrane support. In academia commonly ceramic disks are used for this purpose, but these disks posses a too low surface-area-to-volume ratio for practical applications. Ceramic hollow fibers potentially provide a much larger specific surface area, but applying a defect free thin selective layer on such structures is more intricate. Here we show the successful preparation of a thin polyamide layer on a thin porous hollow α-alumina fiber by interfacial polymerization of piperazine with trimesoyl chloride. Two aspects of the fabrication method are identified as particularly crucial for obtaining a high quality selective layer: i) the layer the ceramic surface should have a sufficient amount of hydroxyl groups for covalent attachment in order to avoid delamination, and ii) controlled drying steps are necessary to avoid local surplus or lack of liquid on the outer surface of the ceramic. To increase the hydroxyl group concentration, and to facilitate the presence of sufficient reactants in a large volume of small pores, the fibers have been coated with a layer of γ-alumina. Sufficiently long drying steps (20 mm) have been employed to avoid uneven drying over the length of the fiber. The obtained fibers show clean water fluxes in the range of 2-5 L m −2 h −1 bar −1 combined with a retention of Rose Bengal above 99%.