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Challenging Isodimorphism Concepts: Formation of Three Crystalline Phases in Poly(hexamethylene-ran-octamethylene carbonate) Copolymers

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Title: Challenging Isodimorphism Concepts: Formation of Three Crystalline Phases in Poly(hexamethylene-ran-octamethylene carbonate) Copolymers
Authors: Liao, Yilong, Pérez-Camargo, Ricardo A., Sardon, Haritz, Martínez de Ilarduya, Antxon, Hu, Wenxian, Liu, Guoming, Wang, Dujin, Müller, Alejandro J.
Contributors: European Commission, Universitat Politècnica de Catalunya. Departament d'Enginyeria Química, Universitat Politècnica de Catalunya. POL - Polímers Industrials Avançats i Biopolímers Tecnològics
Source: Macromolecules
Addi. Archivo Digital para la Docencia y la Investigación
Universidad del País Vasco
UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)
Publisher Information: American Chemical Society (ACS), 2023.
Publication Year: 2023
Subject Terms: Biopolímers, Copolycarbonates, Copolymers, Àrees temàtiques de la UPC::Enginyeria química, 02 engineering and technology, 01 natural sciences, NMR, Copolímers, 0104 chemical sciences, Biopolymers, WAXS, Materials biomèdics, Enginyeria biomèdica, Crystallization, 0210 nano-technology, Biomedical materials, Biomedical engineering, Isodimophic
Description: In this work, poly(hexamethylene-ran-octamethylene carbonate) copolycarbonates were synthesized by melt polycondensation in a wide range of compositions. The copolymers displayed some of the characteristic isodimorphic thermal behavior, such as crystallization for all the compositions and a pseudoeutectic behavior of the melting temperature (Tm) versus composition. The pseudoeutectic point was located at 33 mol % poly(octamethylene carbonate) (POC) content (i.e., corresponding to the PH67O33C copolymer). Surprisingly, the crystallinities (Xc) for a wide range of copolymer compositions were higher than those of the parent components, a phenomenon that has not been observed before in isodimorphic random copolymers. The structural characterization, performed by wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering experiments, revealed unexpected results depending on composition. On the one hand, the poly(hexamethylene carbonate) (PHC)- and POC-rich copolymers crystallize in PHC- and POC-type crystals, as expected. Moreover, upon cooling and heating, in situ WAXS experiments evidenced that these materials undergo reversible solid-solid transitions [δ-α (PHC) and δ-α-β (POC)] present in the parent components but at lower temperatures. On the other hand, a novel behavior was found for copolymers with 33-73 mol % POC (including the pseudoeutectic point), which are those with higher crystallinities than the parent components. For these copolymers, a new crystalline phase that is different from that of both homopolymers was observed. The in situ WAXS results for these copolymers confirmed that this novel phase is stable upon cooling and heating and does not show any crystallographic feature of the parent components or their solid-solid transitions. FTIR experiments confirmed this behavior, revealing that the new phase adopts a polyethylene-like chain conformation that differs from the trans-dominant ones exhibited by the parent components. This finding challenges the established concepts of isodimorphism and questions whether a combination of crystallization modes (isodimorphism and isomorphism) is possible in the same family of random copolymers just by changing the composition.
Document Type: Article
Other literature type
File Description: application/pdf
Language: English
ISSN: 1520-5835
0024-9297
DOI: 10.1021/acs.macromol.3c01265
Access URL: https://pubmed.ncbi.nlm.nih.gov/37900097
http://hdl.handle.net/10810/68290
https://hdl.handle.net/2117/395439
https://doi.org/10.1021/acs.macromol.3c01265
Rights: CC BY
URL: http://creativecommons.org/licenses/by/4.0/Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (http://creativecommons.org/licenses/by/4.0/).
Accession Number: edsair.doi.dedup.....4adf0ae1f21a15a99d0ea25f69867378
Database: OpenAIRE
Description
Abstract:In this work, poly(hexamethylene-ran-octamethylene carbonate) copolycarbonates were synthesized by melt polycondensation in a wide range of compositions. The copolymers displayed some of the characteristic isodimorphic thermal behavior, such as crystallization for all the compositions and a pseudoeutectic behavior of the melting temperature (Tm) versus composition. The pseudoeutectic point was located at 33 mol % poly(octamethylene carbonate) (POC) content (i.e., corresponding to the PH67O33C copolymer). Surprisingly, the crystallinities (Xc) for a wide range of copolymer compositions were higher than those of the parent components, a phenomenon that has not been observed before in isodimorphic random copolymers. The structural characterization, performed by wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering experiments, revealed unexpected results depending on composition. On the one hand, the poly(hexamethylene carbonate) (PHC)- and POC-rich copolymers crystallize in PHC- and POC-type crystals, as expected. Moreover, upon cooling and heating, in situ WAXS experiments evidenced that these materials undergo reversible solid-solid transitions [δ-α (PHC) and δ-α-β (POC)] present in the parent components but at lower temperatures. On the other hand, a novel behavior was found for copolymers with 33-73 mol % POC (including the pseudoeutectic point), which are those with higher crystallinities than the parent components. For these copolymers, a new crystalline phase that is different from that of both homopolymers was observed. The in situ WAXS results for these copolymers confirmed that this novel phase is stable upon cooling and heating and does not show any crystallographic feature of the parent components or their solid-solid transitions. FTIR experiments confirmed this behavior, revealing that the new phase adopts a polyethylene-like chain conformation that differs from the trans-dominant ones exhibited by the parent components. This finding challenges the established concepts of isodimorphism and questions whether a combination of crystallization modes (isodimorphism and isomorphism) is possible in the same family of random copolymers just by changing the composition.
ISSN:15205835
00249297
DOI:10.1021/acs.macromol.3c01265