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 Mw of 120 and 245 kg/mol, 4-arm with Mw of 123 kg/mol, and three linear PLLAs with M...

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Autores principales:	Joanna Bojda, Ewa Piorkowska, Grzegorz Lapienis, Adam Michalski
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	poly(L-lactide) star poly(L-lactide) shear-induced crystallization crystallinity fibrillar nuclei Organic chemistry QD241-441
Acceso en línea:	https://doaj.org/article/4d68ffd1e02446fe92a3ba985545339d
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spelling	oai:doaj.org-article:4d68ffd1e02446fe92a3ba985545339d2021-11-11T18:34:34ZShear-Induced Crystallization of Star and Linear Poly(L-lactide)s10.3390/molecules262166011420-3049https://doaj.org/article/4d68ffd1e02446fe92a3ba985545339d2021-10-01T00:00:00Zhttps://www.mdpi.com/1420-3049/26/21/6601https://doaj.org/toc/1420-3049The 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<sub>w</sub> of 120 and 245 kg/mol, 4-arm with M<sub>w</sub> of 123 kg/mol, and three linear PLLAs with M<sub>w</sub> 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<sub>w</sub> of 240 kg/mol was more intense than that of the 6-arm polymer with similar M<sub>w</sub>, most possibly due to its higher M<sub>z</sub>. However, the influence of shear on the crystallization of the star polymers with M<sub>w</sub> 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.Joanna BojdaEwa PiorkowskaGrzegorz LapienisAdam MichalskiMDPI AGarticlepoly(L-lactide)star poly(L-lactide)shear-induced crystallizationcrystallinityfibrillar nucleiOrganic chemistryQD241-441ENMolecules, Vol 26, Iss 6601, p 6601 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	poly(L-lactide) star poly(L-lactide) shear-induced crystallization crystallinity fibrillar nuclei Organic chemistry QD241-441
spellingShingle	poly(L-lactide) star poly(L-lactide) shear-induced crystallization crystallinity fibrillar nuclei Organic chemistry QD241-441 Joanna Bojda Ewa Piorkowska Grzegorz Lapienis Adam Michalski Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s
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<sub>w</sub> of 120 and 245 kg/mol, 4-arm with M<sub>w</sub> of 123 kg/mol, and three linear PLLAs with M<sub>w</sub> 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<sub>w</sub> of 240 kg/mol was more intense than that of the 6-arm polymer with similar M<sub>w</sub>, most possibly due to its higher M<sub>z</sub>. However, the influence of shear on the crystallization of the star polymers with M<sub>w</sub> 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	article
author	Joanna Bojda Ewa Piorkowska Grzegorz Lapienis Adam Michalski
author_facet	Joanna Bojda Ewa Piorkowska Grzegorz Lapienis Adam Michalski
author_sort	Joanna Bojda
title	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_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_sort	shear-induced crystallization of star and linear poly(l-lactide)s
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/4d68ffd1e02446fe92a3ba985545339d
work_keys_str_mv	AT joannabojda shearinducedcrystallizationofstarandlinearpolyllactides AT ewapiorkowska shearinducedcrystallizationofstarandlinearpolyllactides AT grzegorzlapienis shearinducedcrystallizationofstarandlinearpolyllactides AT adammichalski shearinducedcrystallizationofstarandlinearpolyllactides
_version_	1718431760376659968

Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s

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