@article{1f35c876679840b8a18ec072ecb5ff9a,
title = "Nanoscale Resolution of Electric-field Induced Motion in Ionic Diblock Copolymer Thin Films",
abstract = "Understanding the responses of ionic block copolymers to applied electric fields is crucial when targeting applications in areas such as energy storage, microelectronics, and transducers. This work shows that the identity of counterions in ionic diblock copolymers substantially affects their responses to electric fields, demonstrating the importance of ionic species for materials design. In situ neutron reflectometry measurements revealed that thin films containing imidazolium based cationic diblock copolymers, tetrafluoroborate counteranions led to film contraction under applied electric fields, while bromide counteranions drove expansion under similar field strengths. Coarse-grained molecular dynamics simulations were used to develop a fundamental understanding of these responses, uncovering a nonmonotonic trend in thickness change as a function of field strength. This behavior was attributed to elastic responses of microphase separated diblock copolymer chains resulting from variations in interfacial tension of polymer-polymer interfaces due to the redistribution of counteranions in the presence of electric fields.",
keywords = "electric field, interfacial tension, ionic block copolymer, molecular dynamics, neutron reflectometry",
author = "Dugger, {Jason W.} and Wei Li and Mingtao Chen and Long, {Timothy E.} and Welbourn, {Rebecca J.L.} and Skoda, {Maximilian W.A.} and Browning, {James F.} and Rajeev Kumar and Lokitz, {Bradley S.}",
note = "Funding Information: This research was supported by Oak Ridge National Laboratory{\textquoteright}s (ORNL) Laboratory Directed Research and Development Program. Work was conducted at the Center for Nanophase Materials Sciences and the Spallation Neutron Source, which are U.S. Department of Energy Office of Science User Facilities. We gratefully acknowledge the Science and Technology Facilities Council (STFC) for access to neutron beam time conducted at ISIS, data available at DOI: 10.5286/ isis.e.84782763. The authors are grateful to P. Bonnesen for assistance with the 13C NMR measurements and D. Uhrig for aiding with SEC. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05−00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). Publisher Copyright: {\textcopyright} 2018 American Chemical Society.",
year = "2018",
month = sep,
day = "26",
doi = "10.1021/acsami.8b11220",
language = "English (US)",
volume = "10",
pages = "32678--32687",
journal = "ACS applied materials & interfaces",
issn = "1944-8244",
publisher = "American Chemical Society",
number = "38",
}