Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Molecular Dynamics and Self-Assembly in Double Hydrophilic Block and Random Copolymers
Δημιουργός/Συγγραφέας:	Pipertzis, Achilleas Chroni, Angeliki [EL] Πίσπας, Στέργιος[EN] Pispas, Stergios Swenson, Jan
Ημερομηνία:	2024-11-14
Γλώσσα:	Αγγλικά
ISSN:	1520-6106 1520-5207
DOI:	10.1021/acs.jpcb.4c05398
Άλλο:	39497577
Περίληψη:	We investigate the self-assembly and dynamics of double hydrophilic block copolymers (DHBCs) composed of densely grafted poly[oligo(ethylene glycol) methacrylate] (POEGMA) and poly(vinyl benzyl trimethylammonium chloride) (PVBTMAC) parent blocks by means of calorimetry, small- and wide-angle X-ray scattering (SAXS/WAXS), and dielectric spectroscopy. A weak segregation strength is evident from X-ray measurements, implying a disordered state and reflecting the inherent miscibility between the host homopolymers. The presence of intermixed POEGMA/PVBTMAC nanodomains results in homogeneous molecular dynamics, as evidenced through isothermal dielectric and temperature-modulated DSC measurements. The intermixed process undergoes a glass transition at a temperature approximately 40 K higher than the vitrification of bulk POEGMA segments, and it shifts to an even higher temperature by increasing the content of the hard block. At temperatures below the intermixed glass transition temperature, the confined POEGMA segments between the glassy intermixed regions contribute to a segmental process featuring (i) reduced glass transition temperature (Tg), (ii) reduced dielectric strength, (iii) broader distribution of relaxation times, and (iv) reduced fragility compared to the POEGMA homopolymer. We also observe two glass transition temperatures of dry PVBTMAC, which we attribute to the backbone and side chain segmental relaxation. To the best of our knowledge, this is the first time in the literature that these glass transitions of dry PVBTMAC have been reported. Finally, this study shows that excellent mixing of the two homopolymers is obtained, and this implies that different properties of this copolymer system can be tailored by adjusting the concentration of each homopolymer.
Τίτλος πηγής δημοσίευσης:	The journal of physical chemistry. B
Τόμος/Κεφάλαιο:	128
Τεύχος:	45
Θεματική Κατηγορία:	[EL] Φυσική και θεωρητική χημεία[EN] Physical and theoretical chemistry [EL] Χημική μηχανική[EN] Chemical engineering
Λέξεις-Κλειδιά:	copolymers glass transition homopolymers insulators molecular dynamics
Κάτοχος πνευματικών δικαιωμάτων:	© 2024 The Authors. Published by American Chemical Society
Όροι και προϋποθέσεις δικαιωμάτων:	This publication is licensed under CC-BY 4.0 .
Ηλεκτρονική διεύθυνση στον εκδότη (link):	https://doi.org/10.1021/acs.jpcb.4c05398
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο