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. 2023 Jul 13:11:1234763.
doi: 10.3389/fchem.2023.1234763. eCollection 2023.

Novel terephthalamide diol monomers synthesis from PET waste to Poly(Urethane acrylates)

Genny Pastore  1 , Roberto Giacomantonio  1 , Gabriele Lupidi  1 , Francesca Stella  1 , Roberta Risoluti  2 , Elena Papa  2 , Roberto Ballini  1 , Fabrizio Sarasini  3 , Jacopo Tirillò  3 , Enrico Marcantoni  1 , Serena Gabrielli  1
Affiliations

Novel terephthalamide diol monomers synthesis from PET waste to Poly(Urethane acrylates)

Genny Pastore et al. Front Chem. .

Abstract

Due to its excellent properties, poly(ethylene terephthalate) (PET) is one of the most produced and consumed polymers. Among plastics, it represents the main contributor to environmental pollution. Following the circular economy model, the chemical upcycling of PET reduces the amount of waste generated and transforms it into high-value products. The depolymerization of poly(ethylene terephthalate) into oligomers or monomers leads to forming a library of reactive molecules involved in different polymerization processes to obtain compounds with improved properties. Herein, several β-hydroxy amines were synthesized and used for the chemical recycling of water bottle waste by an environmental benefit aminolysis process to get very useful new terephthalamide diol monomers. The recycled diol monomers were subsequently exploited to synthesize poly(urethane acrylates) (PUAs) UV-curable coatings, and their chemical, thermal and mechanical characterizations were performed. The results show the great potential of the developed synthesis protocols to obtain PUAs with final properties that can be modulated to meet the requirements of different applications.

Keywords: PET; PUA; characterization; chemical recycling; circular economy.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
“Polymer to Polymer” approach: from PET waste recycling to PUA UV-curable coatings.
SCHEME 1
SCHEME 1
The general procedure for β-hydroxylamines (4a-g) synthesis starting from nitro-derivatives (3a-g).
SCHEME 2
SCHEME 2
The general procedure for PET grinding and Mw irradiation to terephthalamide moieties 6a-f’, and preparation of UV-curable coating films 9a-g’.
FIGURE 2
FIGURE 2
FT-IR spectra overlay: PET (blue) vs. compounds 6a (black).
SCHEME 3
SCHEME 3
PUA UV-curable polymers total synthesis.
FIGURE 3
FIGURE 3
FT-IR spectra overlay compounds 10a (red), 12a (black) and 9a (blue).
FIGURE 4
FIGURE 4
TGA thermograms of 9a, as an example.
FIGURE 5
FIGURE 5
(A) Typical DSC thermogram over the entire temperature range and (B) close-up views of the DSC traces of all PUA films. In figure (B) the average value ± standard deviation of the glass transition temperature is included.
FIGURE 6
FIGURE 6
(A) Typical tensile stress-strain curves and (B) relevant tensile characteristics of all PUA films.
See this image and copyright information in PMC

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