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Title: Structures of Partially Fluorinated Bottlebrush Polymers in Thin Films

Abstract

Here, we performed multiscale molecular dynamics (MD) simulations of bottlebrush polymers with fluorinated side chains to investigate the influence of the bottlebrush architecture on the spatial distribution of fluorinated moieties. In thin films, coarse-grained MD simulations reveal that interfaces are characterized by backbone depletion with side chains at the interface oriented parallel to the surface. At the molecular level, atomistic MD simulations show that fluorine atoms in the bottlebrush are preferentially located at air–film interfaces. Both simulation results indicate enrichment of fluorinated moieties at the air–film interface. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) confirms the enhancement of fluorinated moieties in both bottlebrush and linear copolymer films. ToF-SIMS also shows that for long linear chains the difference between the concentration of fluorinated moieties at the air–film interface and the concentration at the bulk or at the middle of the film is relatively higher than those observed in shorter linear chains (macromonomers) or bottlebrushes. Although there are differences in the distributions of fluorine moieties between linear chains and bottlebrushes, simulations suggest that the effect of polymer architecture on contact angle and surface energy is only significant at low molecular weights. Measurements of the contact angle of films composed of different modestly highmore » molecular weights of linear chains and bottlebrushes do not show a significant difference in the value of the contact angle, in a way restricting the tunability of surface energy and contact angle via polymer architecture. With these results, our study provides insights into the effective use of partially fluorinated bottlebrush polymer for directed self-assemblies at surfaces in thin films. Specifically, achieving a high degree of difference in surface energies for fluorinated thin films is limited to films with low molecular weight constituents, and the effect of molecular architecture is subtle, suggesting it is insufficient to only rely on this strategy to further lower the surface energy of these films for applications directed toward tuned wettability, adhesive interactions, and fouling resistance.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1616799
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
ACS Applied Polymer Materials
Additional Journal Information:
Journal Volume: 2; Journal Issue: 2; Journal ID: ISSN 2637-6105
Publisher:
ACS Publications
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; thin films; fluorinated polymers; bottlebrush polymers; molecular dynamics simulations; ToF-SIMS; contact angle

Citation Formats

Chang, Dongsook, Lorenz, Matthias, Burch, Matthew J., Ovchinnikova, Olga S., Hong, Kunlun, Sumpter, Bobby, and Carrillo, Jan Michael. Structures of Partially Fluorinated Bottlebrush Polymers in Thin Films. United States: N. p., 2019. Web. https://doi.org/10.1021/acsapm.9b00763.
Chang, Dongsook, Lorenz, Matthias, Burch, Matthew J., Ovchinnikova, Olga S., Hong, Kunlun, Sumpter, Bobby, & Carrillo, Jan Michael. Structures of Partially Fluorinated Bottlebrush Polymers in Thin Films. United States. https://doi.org/10.1021/acsapm.9b00763
Chang, Dongsook, Lorenz, Matthias, Burch, Matthew J., Ovchinnikova, Olga S., Hong, Kunlun, Sumpter, Bobby, and Carrillo, Jan Michael. Tue . "Structures of Partially Fluorinated Bottlebrush Polymers in Thin Films". United States. https://doi.org/10.1021/acsapm.9b00763. https://www.osti.gov/servlets/purl/1616799.
@article{osti_1616799,
title = {Structures of Partially Fluorinated Bottlebrush Polymers in Thin Films},
author = {Chang, Dongsook and Lorenz, Matthias and Burch, Matthew J. and Ovchinnikova, Olga S. and Hong, Kunlun and Sumpter, Bobby and Carrillo, Jan Michael},
abstractNote = {Here, we performed multiscale molecular dynamics (MD) simulations of bottlebrush polymers with fluorinated side chains to investigate the influence of the bottlebrush architecture on the spatial distribution of fluorinated moieties. In thin films, coarse-grained MD simulations reveal that interfaces are characterized by backbone depletion with side chains at the interface oriented parallel to the surface. At the molecular level, atomistic MD simulations show that fluorine atoms in the bottlebrush are preferentially located at air–film interfaces. Both simulation results indicate enrichment of fluorinated moieties at the air–film interface. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) confirms the enhancement of fluorinated moieties in both bottlebrush and linear copolymer films. ToF-SIMS also shows that for long linear chains the difference between the concentration of fluorinated moieties at the air–film interface and the concentration at the bulk or at the middle of the film is relatively higher than those observed in shorter linear chains (macromonomers) or bottlebrushes. Although there are differences in the distributions of fluorine moieties between linear chains and bottlebrushes, simulations suggest that the effect of polymer architecture on contact angle and surface energy is only significant at low molecular weights. Measurements of the contact angle of films composed of different modestly high molecular weights of linear chains and bottlebrushes do not show a significant difference in the value of the contact angle, in a way restricting the tunability of surface energy and contact angle via polymer architecture. With these results, our study provides insights into the effective use of partially fluorinated bottlebrush polymer for directed self-assemblies at surfaces in thin films. Specifically, achieving a high degree of difference in surface energies for fluorinated thin films is limited to films with low molecular weight constituents, and the effect of molecular architecture is subtle, suggesting it is insufficient to only rely on this strategy to further lower the surface energy of these films for applications directed toward tuned wettability, adhesive interactions, and fouling resistance.},
doi = {10.1021/acsapm.9b00763},
journal = {ACS Applied Polymer Materials},
number = 2,
volume = 2,
place = {United States},
year = {2019},
month = {12}
}

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