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Improved chemical recyclability of 2,5-furandicarboxylate polyesters enabled by acid-sensitive spirocyclic ketal units

Valsange, Nitin LU ; Warlin, Niklas LU ; Mankar, Smita LU ; Rehnberg, Nicola LU orcid ; Zhang, Baozhong LU and Jannasch, Patric LU orcid (2024) In Green Chemistry 26(5). p.2858-2873
Abstract
Incorporating hydrolytically sensitive functional groups into polymer backbones provides a feasible strategy to trigger their degradation to the starting monomers, thus enabling chemical recycling of the material. Here, we present two series of copolyesters in which a biobased spirocyclic ketal-functional diester monomer was incorporated into poly(butylene 2,5-furandicarboxylate) (PBLF) and poly(hexamethylene 2,5-furandicarboxylate) (PHLF), respectively. A two-step melt polycondensation resulted in copolyesters with moderate to high molecular weights, as confirmed by intrinsic viscosity values between 0.5-1.04 dL g-1. Thermogravimetric analysis showed a thermal stability up to 275 °C, and increasing char yields upon... (More)
Incorporating hydrolytically sensitive functional groups into polymer backbones provides a feasible strategy to trigger their degradation to the starting monomers, thus enabling chemical recycling of the material. Here, we present two series of copolyesters in which a biobased spirocyclic ketal-functional diester monomer was incorporated into poly(butylene 2,5-furandicarboxylate) (PBLF) and poly(hexamethylene 2,5-furandicarboxylate) (PHLF), respectively. A two-step melt polycondensation resulted in copolyesters with moderate to high molecular weights, as confirmed by intrinsic viscosity values between 0.5-1.04 dL g-1. Thermogravimetric analysis showed a thermal stability up to 275 °C, and increasing char yields upon incorporation of the spirocyclic monomer. The crystallinity and melting points of the copolyesters decreased with the increasing content of the spirocyclic ketal units in the backbone. Copolyesters containing up to 15% of the spiro-ketal units were semicrystalline, while those containing 20 and 50% spiro-ketal units were completely amorphous. The hydrolytic degradation of copolyesters from the PHLF series was investigated using 3-12 M aq. HCl, and were found to degrade faster than the corresponding homopolyesters. Acid-catalyzed cleavage of the randomly distributed spiro ketal units promoted the rapid fragmentation of the polymer chain into small oligomers, which were subsequently hydrolyzed to the original chemical building blocks. The ketone-terminated telechelic oligomers obtained after the degradation of spirocyclic ketal units were also investigated in the direct polymerization with pentaerythritol. The initial results implied that the oligomers can be re-polymerized into the original polymer. Hence, this work demonstrated a feasible pathway towards chemically recyclable 2,5-furandicarboxylate polyesters with a tuneable degree of crystallinity
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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Green Chemistry
volume
26
issue
5
pages
16 pages
publisher
Royal Society of Chemistry
external identifiers
  • scopus:85184005308
ISSN
1463-9270
DOI
10.1039/D3GC03099G
language
English
LU publication?
yes
id
1bfdc6ee-e349-4b6a-a15b-a8f89a635770
date added to LUP
2023-03-12 22:05:37
date last changed
2024-03-05 09:06:37
@article{1bfdc6ee-e349-4b6a-a15b-a8f89a635770,
  abstract     = {{Incorporating hydrolytically sensitive functional groups into polymer backbones provides a feasible strategy to trigger their degradation to the starting monomers, thus enabling chemical recycling of the material. Here, we present two series of copolyesters in which a biobased spirocyclic ketal-functional diester monomer was incorporated into poly(butylene 2,5-furandicarboxylate) (PBLF) and poly(hexamethylene 2,5-furandicarboxylate) (PHLF), respectively. A two-step melt polycondensation resulted in copolyesters with moderate to high molecular weights, as confirmed by intrinsic viscosity values between 0.5-1.04 dL g<sup>-1</sup>. Thermogravimetric analysis showed a thermal stability up to 275 °C, and increasing char yields upon incorporation of the spirocyclic monomer. The crystallinity and melting points of the copolyesters decreased with the increasing content of the spirocyclic ketal units in the backbone. Copolyesters containing up to 15% of the spiro-ketal units were semicrystalline, while those containing 20 and 50% spiro-ketal units were completely amorphous. The hydrolytic degradation of copolyesters from the PHLF series was investigated using 3-12 M aq. HCl, and were found to degrade faster than the corresponding homopolyesters. Acid-catalyzed cleavage of the randomly distributed spiro ketal units promoted the rapid fragmentation of the polymer chain into small oligomers, which were subsequently hydrolyzed to the original chemical building blocks. The ketone-terminated telechelic oligomers obtained after the degradation of spirocyclic ketal units were also investigated in the direct polymerization with pentaerythritol. The initial results implied that the oligomers can be re-polymerized into the original polymer. Hence, this work demonstrated a feasible pathway towards chemically recyclable 2,5-furandicarboxylate polyesters with a tuneable degree of crystallinity<br/>}},
  author       = {{Valsange, Nitin and Warlin, Niklas and Mankar, Smita and Rehnberg, Nicola and Zhang, Baozhong and Jannasch, Patric}},
  issn         = {{1463-9270}},
  language     = {{eng}},
  number       = {{5}},
  pages        = {{2858--2873}},
  publisher    = {{Royal Society of Chemistry}},
  series       = {{Green Chemistry}},
  title        = {{Improved chemical recyclability of 2,5-furandicarboxylate polyesters enabled by acid-sensitive spirocyclic ketal units}},
  url          = {{http://dx.doi.org/10.1039/D3GC03099G}},
  doi          = {{10.1039/D3GC03099G}},
  volume       = {{26}},
  year         = {{2024}},
}