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Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s
The influence of macromolecular architecture on shear-induced crystallization of poly(L-lactide) (PLLA) was studied. To this aim, three star PLLAs, 6-arm with M(w) of 120 and 245 kg/mol, 4-arm with M(w) of 123 kg/mol, and three linear PLLAs with M(w) of 121, 240 and 339 kg/mol, were synthesized and...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8588257/ https://www.ncbi.nlm.nih.gov/pubmed/34771011 http://dx.doi.org/10.3390/molecules26216601 |
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author | Bojda, Joanna Piorkowska, Ewa Lapienis, Grzegorz Michalski, Adam |
author_facet | Bojda, Joanna Piorkowska, Ewa Lapienis, Grzegorz Michalski, Adam |
author_sort | Bojda, Joanna |
collection | PubMed |
description | The influence of macromolecular architecture on shear-induced crystallization of poly(L-lactide) (PLLA) was studied. To this aim, three star PLLAs, 6-arm with M(w) of 120 and 245 kg/mol, 4-arm with M(w) of 123 kg/mol, and three linear PLLAs with M(w) of 121, 240 and 339 kg/mol, were synthesized and examined. The PLLAs were sheared at 170 and 150 °C, at 5/s, 10/s and 20/s for 20 s, 10 s and 5 s, respectively, and then cooled at 10 or 30 °C/min. Shear-induced crystallization during cooling was followed by a light depolarization method, whereas the crystallized specimens were examined by DSC, 2D-WAXS, 2D-SAXS and SEM. The effect of shear depended on the shearing conditions, cooling rate and polymer molar mass but it was also affected by the macromolecular architecture. The shear-induced crystallization of linear PLLA with M(w) of 240 kg/mol was more intense than that of the 6-arm polymer with similar M(w), most possibly due to its higher M(z). However, the influence of shear on the crystallization of the star polymers with M(w) close to 120 kg/mol was stronger than on that of their linear analog. This was reflected in higher crystallization temperature, as well as crystallinity achieved during cooling. |
format | Online Article Text |
id | pubmed-8588257 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-85882572021-11-13 Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s Bojda, Joanna Piorkowska, Ewa Lapienis, Grzegorz Michalski, Adam Molecules Article The influence of macromolecular architecture on shear-induced crystallization of poly(L-lactide) (PLLA) was studied. To this aim, three star PLLAs, 6-arm with M(w) of 120 and 245 kg/mol, 4-arm with M(w) of 123 kg/mol, and three linear PLLAs with M(w) of 121, 240 and 339 kg/mol, were synthesized and examined. The PLLAs were sheared at 170 and 150 °C, at 5/s, 10/s and 20/s for 20 s, 10 s and 5 s, respectively, and then cooled at 10 or 30 °C/min. Shear-induced crystallization during cooling was followed by a light depolarization method, whereas the crystallized specimens were examined by DSC, 2D-WAXS, 2D-SAXS and SEM. The effect of shear depended on the shearing conditions, cooling rate and polymer molar mass but it was also affected by the macromolecular architecture. The shear-induced crystallization of linear PLLA with M(w) of 240 kg/mol was more intense than that of the 6-arm polymer with similar M(w), most possibly due to its higher M(z). However, the influence of shear on the crystallization of the star polymers with M(w) close to 120 kg/mol was stronger than on that of their linear analog. This was reflected in higher crystallization temperature, as well as crystallinity achieved during cooling. MDPI 2021-10-31 /pmc/articles/PMC8588257/ /pubmed/34771011 http://dx.doi.org/10.3390/molecules26216601 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Article Bojda, Joanna Piorkowska, Ewa Lapienis, Grzegorz Michalski, Adam Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s |
title | Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s |
title_full | Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s |
title_fullStr | Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s |
title_full_unstemmed | Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s |
title_short | Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s |
title_sort | shear-induced crystallization of star and linear poly(l-lactide)s |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8588257/ https://www.ncbi.nlm.nih.gov/pubmed/34771011 http://dx.doi.org/10.3390/molecules26216601 |
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