Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Thin films of poly(isoprene-b-ethylene oxide) diblock copolymers on mica: An atomic force microscopy study
Δημιουργός/Συγγραφέας:	Kalloudis M. Glynos E. [EL] Πίσπας, Στέργιος[EN] Pispas, Stergios Walker J. Koutsos V.
Ημερομηνία:	2013
Γλώσσα:	Αγγλικά
ISSN:	0743-7463
DOI:	10.1021/la400041x
Περίληψη:	The structural behavior of three amphiphilic semicrystalline poly(isoprene-b-ethylene oxide) block copolymers (PI-b-PEO) with different PEO volume fraction (fPEO = 0.32, 0.49, and 0.66), spin-coated on freshly cleaved mica surfaces from aqueous solutions, was investigated by atomic force microscopy. We focus on the dependence of the resulting thin film nanostructures on the molecular characteristics (fPEO and molecular weight) and the adsorbed amount. The nanostructures obtained immediately after spin-coating were robust and remained unchanged after annealing and/or aging. The PEO affinity for the highly hydrophilic mica and the tendency of the hydrophobic and low surface energy PI to dewet and be at the free interface caused the soft PI-b-PEO micelles to collapse leading to the formation of 2D dendritic networks over mica. We show that, for all three polymers, the dendritic monolayer thickness can be predicted by a model consisting of a PEO crystallized layer (directly on top of mica) of the same thickness in all cases and a PI brush layer on top. In thicker areas, polymer material self-assembled into conelike multilamellar bilayers on top of the monolayer and oriented parallel to the substrate for both symmetric and asymmetric diblock copolymers with the lowest fPEO. We compare the lateral morphology of the films and discuss the thickness heterogeneity, which results from the coupling and competition of crystallization kinetics, phase separation, and wetting/dewetting phenomena highlighting the role of the two blocks to inhibit or enhance certain morphologies. We show that the deviation of the fPEO = 0.32 thin film from its bulk phase structure (cylinders in hexagonal lattice) continues for several lamellar bilayers away from the substrate. For the asymmetric PI-b-PEO polymer with the higher PEO volume fraction (fPEO = 0.66) and higher APT, laterally extensive stacks of flat-on lamellar crystallites formed on the surface demonstrating the crucial role of the PEO crystallization.
Τίτλος πηγής δημοσίευσης:	Langmuir
Τόμος/Κεφάλαιο:	29
Τεύχος:	7
Σελίδες:	2339-2349
Θεματική Κατηγορία:	[EL] Φυσική και θεωρητική χημεία[EN] Physical and theoretical chemistry
Αξιολόγηση από ομότιμους (peer reviewed):	Ναι
Κάτοχος πνευματικών δικαιωμάτων:	© 2013 American Chemical Society.
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο