Rights statement: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Macromolecules, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.macromol.0c01214
Accepted author manuscript, 898 KB, PDF document
Available under license: CC BY-NC: Creative Commons Attribution-NonCommercial 4.0 International License
Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Precise Microstructure Control in Poly(hydroxybutyrate- co-lactic Acid) Copolymers Prepared by an Yttrium Amine Bis(phenolate) Complex
AU - Platel, R.H.
AU - Hurst, A.R.
N1 - This document is the Accepted Manuscript version of a Published Work that appeared in final form in Macromolecules, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/acs.macromol.0c01214
PY - 2020/12/22
Y1 - 2020/12/22
N2 - A diamino-bis(phenolate) yttrium amide complex, 1, was used as an initiator in the ring-opening copolymerization of rac-lactide (rac-LA) and rac-β-butyrolactone (rac-β-BL) in toluene at ambient temperature. Copolymers were prepared across a wide composition range (10-89% LA content), and the copolymer composition closely matched the monomer feed ratio. The copolymers had Tg values ranging from 3.8 °C (for a copolymer with 10% LA content) to 44.0 °C (for a copolymer with 89% LA content). Tm ranged from 132 to 144 °C for copolymers with LA composition 48-10%. The copolymer microstructure was determined using 1H and 13C{1H} NMR spectroscopy of copolymers and through reaction monitoring by NMR spectroscopy. This revealed that no BB diads are formed in the copolymer in the presence of any rac-LA monomer, even at very high concentrations of rac-β-BL. However, when [LA] = 0, rac-β-BL is rapidly polymerized. The copolymers thus have a microstructure consisting of two distinct regions, one containing both LA and BL units in an even distribution and one containing solely BL or LA units, depending on the monomer feed ratio.
AB - A diamino-bis(phenolate) yttrium amide complex, 1, was used as an initiator in the ring-opening copolymerization of rac-lactide (rac-LA) and rac-β-butyrolactone (rac-β-BL) in toluene at ambient temperature. Copolymers were prepared across a wide composition range (10-89% LA content), and the copolymer composition closely matched the monomer feed ratio. The copolymers had Tg values ranging from 3.8 °C (for a copolymer with 10% LA content) to 44.0 °C (for a copolymer with 89% LA content). Tm ranged from 132 to 144 °C for copolymers with LA composition 48-10%. The copolymer microstructure was determined using 1H and 13C{1H} NMR spectroscopy of copolymers and through reaction monitoring by NMR spectroscopy. This revealed that no BB diads are formed in the copolymer in the presence of any rac-LA monomer, even at very high concentrations of rac-β-BL. However, when [LA] = 0, rac-β-BL is rapidly polymerized. The copolymers thus have a microstructure consisting of two distinct regions, one containing both LA and BL units in an even distribution and one containing solely BL or LA units, depending on the monomer feed ratio.
KW - Amides
KW - Lactic acid
KW - Microstructure
KW - Monomers
KW - Nuclear magnetic resonance spectroscopy
KW - Amide complexes
KW - Composition ranges
KW - Copolymer compositions
KW - Copolymer microstructures
KW - Hydroxybutyrate
KW - Microstructure control
KW - Reaction monitoring
KW - Ring opening copolymerization
KW - Yttrium compounds
U2 - 10.1021/acs.macromol.0c01214
DO - 10.1021/acs.macromol.0c01214
M3 - Journal article
VL - 53
SP - 10773
EP - 10784
JO - Macromolecules
JF - Macromolecules
SN - 0024-9297
IS - 24
ER -