1. Αποθετήριο Παραδοτέων Υποτρόφων Δράσεων ΕΣΠΑ Τριτοβάθμιας Εκπαίδευσης 2017-2023
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3. Ερευνητικές ομάδες

Τύπος:	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Structure and dynamics of highly attractive polymer nanocomposites in the semi-dilute regime: the role of interfacial domains and bridging chains
Συγγραφέας:	[EL] Σκούντζος, Εμμανουήλ-Θεόδωρος[EN] Skountzos, Emmanouil-Theodoros [EL] Καραδήμα, Αικατερίνη[EN] Karadima, Katerina [EL] Μαυράντζας, Βλάσιος[EN] Mavrantzas, Vlasis
Ημερομηνία:	16/08/2021
Περίληψη:	Detailed molecular dynamics (MD) simulations are employed to study how the presence of adsorbed domains and nanoparticle bridging chains affect the structural, conformational, thermodynamic, and dynamic properties of attractive polymer nanocomposite melts in the semi-dilute regime. As a model system we have chosen an unentangled poly(ethylene glycol) (PEG) matrix containing amorphous spherical silica nanoparticles with different diameters and at different concentrations. Emphasis is placed on properties such as the polymer mass density profile around nanoparticles, the compressibility of the system, the mean squared end-to-end distance of PEG chains, their orientational and diffusive dynamics, the single chain form factor, and the scattering functions. Our analysis reveals a significant impact of the adsorbed, interfacial polymer on the microscopic dynamic and conformational properties of the nanocomposite, especially under conditions favoring higher surface-to-volume ratios (e.g., for small nanoparticle sizes at fixed nanoparticle loading, or for higher silica concentrations). Simultaneously, adsorbed polymer chains adopt graft-like conformations, a feature that allows them to considerably extend away from the nanoparticle surface to form bridges with other nanoparticles. These bridges drive the formation of a nanoparticle network whose strength (number of tie chains per nanoparticle) increases substantially with increasing concentration of the polymer matrix in nanoparticles, or with decreasing nanoparticle size at fixed nanoparticle concentration. The presence of hydroxyl groups at the ends of PEG chains plays a key role in the formation of the network. If hydroxyl groups are substituted by methoxy ones, the simulations reveal that the number of bridging chains per nanoparticle decreases dramatically, thus the network formed is less dense and less strong mechanically, and has a smaller impact on the properties of the nanocomposite. Our simulations predict further that the isothermal compressibility and thermal expansion coefficient of PEG-silica nanocomposites are significantly lower than those of pure PEG, with their values decreasing practically linear with increasing concentration of the nanocomposite in nanoparticles.
Γλώσσα:	Αγγλικά
Σελίδες:	25
DOI:	10.3390/ polym13162749
EISSN:	2073-4360
Θεματική κατηγορία:	[EL] Χημική μηχανική[EN] Chemical Engineering
Λέξεις-κλειδιά:	polymer nanocomposites; polymer network; molecular simulations; Molecular Dynamics; silica; PEG
Κάτοχος πνευματικών δικαιωμάτων:	© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Όροι και προϋποθέσεις δικαιωμάτων:	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/).
Ηλεκτρονική διεύθυνση του τεκμηρίου στον εκδότη:	https://www.mdpi.com/2073-4360/13/16/2749
Ηλεκτρονική διεύθυνση περιοδικού:	https://www.mdpi.com/journal/polymers
Τίτλος πηγής δημοσίευσης:	Polymers
Τεύχος:	13 16
Σελίδες τεκμηρίου (στην πηγή):	Article no 2749
Σημειώσεις:	This research is co-financed by Greece and the European Union (European Social FundESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning 2014–2020» in the context of the project “Study of the rheology of polymer nanocomposite melts by combining atomistic simulations and constitutive modelling (PNC Rheo) (MIS 5047161)”
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