In situ dissolution and swelling of confined lamellar polymer crystals through exposure to humid air

Abstract: Using a hydrophobic-hydrophilic poly(styrene)-b-poly(ethylene oxide) diblock copolymer (PS-b-PEO), we formed sandwich-like micron-sized thin platelets via crystallization in solution. These platelets consisted of a crystalline PEO lamella confined between two glassy PS layers and were deposited on a solid substrate. Using in-situ optical microscopy, we followed the temporal and spatial changes in thickness and morphology of these sandwich-like platelets induced by exposure to humid air. As water is a good solvent for PEO but a nonsolvent for PS, we observed first the dissolution of the confined crystalline PEO layers characterized by sharp dissolution front propagating at an almost constant velocity as expected for case II diffusion into a solid. The resulting hydrated PEO brushes absorbed further water until equilibration of the respective chemical potentials, accompanied by a change from a planar to a dome-shaped morphology which could be fully reversed by exposure to dry air. Repeated swelling/de-swelling cycles demonstrated stability and reproducibility of these developments taking place at distinctly different transport rates. We discuss the underlying processes of water permeation into and efflux from the PEO layers

Standort
Deutsche Nationalbibliothek Frankfurt am Main
Umfang
Online-Ressource
Ausgabe
[Manuskript-Version]
Sprache
Englisch

Schlagwort
Diblockcopolymere

Ereignis
Veröffentlichung
(wo)
Freiburg
(wer)
Universität
(wann)
2022
Urheber

DOI
10.6094/UNIFR/228227
URN
urn:nbn:de:bsz:25-freidok-2282274
Rechteinformation
Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
Letzte Aktualisierung
15.08.2025, 07:23 MESZ

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  • 2022

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