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About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts
Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 °C with variation of catalyst, catalyst concentration and annealing time. The transformation of the initially formed low melting (LT(m)) crystallites, having melting temp...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Royal Society of Chemistry
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8693987/ https://www.ncbi.nlm.nih.gov/pubmed/35424240 http://dx.doi.org/10.1039/d0ra10012a |
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author | Weidner, Steffen M. Meyer, Andreas Chatti, Saber Kricheldorf, Hans R. |
author_facet | Weidner, Steffen M. Meyer, Andreas Chatti, Saber Kricheldorf, Hans R. |
author_sort | Weidner, Steffen M. |
collection | PubMed |
description | Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 °C with variation of catalyst, catalyst concentration and annealing time. The transformation of the initially formed low melting (LT(m)) crystallites, having melting temperatures (T(m)) < 180 °C into high melting (HT(m)) crystallites having T(m) values > 189 °C was monitored by means of DSC measurements and characterized in selected cases by SAXS measurements. It was confirmed that the formation of HT(m) crystallites involves a significant growth of the thickness of the lamellar crystallites along with smoothing of their surface. Annealing at 170 °C for 1 d or longer causes thermal degradation with lowering of the molecular weights, a gradual transition of cyclic into linear chains and a moderate decrease of lamellar thickness. An unexpected result revealed by MALDI TOF mass spectrometry is a partial reorganization of the molecular weight distribution driven by a gain of crystallization enthalpy. |
format | Online Article Text |
id | pubmed-8693987 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | The Royal Society of Chemistry |
record_format | MEDLINE/PubMed |
spelling | pubmed-86939872022-04-13 About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts Weidner, Steffen M. Meyer, Andreas Chatti, Saber Kricheldorf, Hans R. RSC Adv Chemistry Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 °C with variation of catalyst, catalyst concentration and annealing time. The transformation of the initially formed low melting (LT(m)) crystallites, having melting temperatures (T(m)) < 180 °C into high melting (HT(m)) crystallites having T(m) values > 189 °C was monitored by means of DSC measurements and characterized in selected cases by SAXS measurements. It was confirmed that the formation of HT(m) crystallites involves a significant growth of the thickness of the lamellar crystallites along with smoothing of their surface. Annealing at 170 °C for 1 d or longer causes thermal degradation with lowering of the molecular weights, a gradual transition of cyclic into linear chains and a moderate decrease of lamellar thickness. An unexpected result revealed by MALDI TOF mass spectrometry is a partial reorganization of the molecular weight distribution driven by a gain of crystallization enthalpy. The Royal Society of Chemistry 2021-01-12 /pmc/articles/PMC8693987/ /pubmed/35424240 http://dx.doi.org/10.1039/d0ra10012a Text en This journal is © The Royal Society of Chemistry https://creativecommons.org/licenses/by-nc/3.0/ |
spellingShingle | Chemistry Weidner, Steffen M. Meyer, Andreas Chatti, Saber Kricheldorf, Hans R. About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts |
title | About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts |
title_full | About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts |
title_fullStr | About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts |
title_full_unstemmed | About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts |
title_short | About the transformation of low T(m) into high T(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts |
title_sort | about the transformation of low t(m) into high t(m) poly(l-lactide)s by annealing under the influence of transesterification catalysts |
topic | Chemistry |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8693987/ https://www.ncbi.nlm.nih.gov/pubmed/35424240 http://dx.doi.org/10.1039/d0ra10012a |
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