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Plastic packaging has gained an increasing amount of attention in all aspects of society. Over the past several decades, plastics became the material of choice due to their excellent properties, performance, and economics, but the end of life of plastics is not well managed. This has led to plastic waste in our environment, especially the oceans, rivers, and estuaries, driving legislative, industrial, and voluntary initiatives to make the necessary pivot to circularity. While the plastics recycling industry has made many advances in its relatively short life, there are still many technical and societal hurdles to be overcome. The goal of this work is not to provide a complete review of recycling as it pertains to circularity, but rather to highlight the technical gaps that need to be collaboratively addressed by the entire plastics community to achieve circularity. Each stage along the path, from design of packaging and materials of construction to sortation, recycling, and reprocessing are ripe for innovation. The most relevant issues are introduced to provide a starting point for research across all fields of polymer science to aid in reducing the environmental impact of plastic packaging waste.

A novel methodology for in situ cross-linking of polymeric fibers during electrospinning is described. The electrospinning apparatus was modified to facilitate UV irradiation of the electrospun fibers while in flight to the collector target. Three polymers with different mol % of the photoreactive cinnamate functional group (4, 9, and 13 mol %) were synthesized and utilized for this study. Fibers of cinnamate functionalized poly(methyl methacrylate-co-2-hydroxyethyl acrylate) were cross-linked in situ by UV irradiation during electrospinning. Subsequent FTIR measurements on irradiated and nonirradiated electrospun fibers indicated both [2π + 2π] cycloaddition of the vinylene CC and trans−cis photoisomerization of the cinnamate group. Furthermore, the irradiated copolymers were observed to form insoluble gels which indicated that the photodimerization was the primary photoprocess during UV irradiation, leading to the formation of a cross-linked network. As expected, it was found that the gel fraction increased with increasing mol % of the cinnamate species.

Summary: Coumarin containing poly(ethylene glycol) monols and diols were prepared in a telechelic fashion using quantitative end group esterification. The coumarin modified poly(ethylene glycol) monols and diols were solution cast into films (1 to 15 μm) and chain extended via the dimerization of the coumarin derivatives with UVA (>300 nm) light irradiation. The coumarin‐modified PEG diol doubled in molecular weight, and the molecular weight distribution increased from 1.17 to 2.75 upon exposure to 110 J · cm−2 of UVA light. The chain extended poly(ethylene glycol)s were subsequently converted to their original molecular weight via the photocleavage reaction of the coumarin dimer at 254 nm with less than 2 J · cm−2. The photoreversible chain length modulation was monitored utilizing GPC, DSC and UV‐Vis spectroscopy.Molecular weight modulation of COU‐PEG‐COU.magnified imageMolecular weight modulation of COU‐PEG‐COU.

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