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Title: Side chain dynamics in semiconducting polymer MEH-PPV

We report that the characteristic nanoscale dynamics of the alkyl side groups in the light-emitting polymer poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] have been investigated using quasi-elastic neutron scattering (QENS). The measurements were taken below the polymer's glass transition (T ≤ T g ≃ 353 K), where the main backbone is in a rigid state and does not contribute to the broadening of the QENS signal. An analytical diffusion model consisting of a static term and two dynamical components, characterizing the flexible side groups, provide an excellent fit to the experimental data. The two observed dynamical processes are all localized in character, with no meaningful dependence on temperature. The faster process, with characteristic timescale of ~18 ps at room temperature (RT), can be linked to the average mobility of the terminal protons of the alkyl chain, while the slower process, with characteristic timescale of ~170 ps at RT, to those protons at the other end of the alkyl chain, closest to the backbone. Lastlyl, while the fraction of mobile protons contributing to the QENS signal increases with increasing temperature, the characteristic timescale and confining volume within which the protons are able to move locally depend chiefly on the polymer conformational state.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [2] ;  [1] ; ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Polymer Science
Additional Journal Information:
Journal Volume: 136; Journal Issue: 0; Journal ID: ISSN 0021-8995
Publisher:
Wiley
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; optical and photovoltaic applications; polymer dynamics; quasi‐elastic neutron scattering; semi‐conducting polymer; spectroscopy
OSTI Identifier:
1488691
Alternate Identifier(s):
OSTI ID: 1485521

Osti, Naresh C., Mamontov, Eugene, Daemen, Luke L., Browning, Jim, Keum, Jong K., Ho, Hoi Chun, Chen, Jihua, Hong, Kunlun, and Omar Diallo, Souleymane. Side chain dynamics in semiconducting polymer MEH-PPV. United States: N. p., Web. doi:10.1002/APP.47394.
Osti, Naresh C., Mamontov, Eugene, Daemen, Luke L., Browning, Jim, Keum, Jong K., Ho, Hoi Chun, Chen, Jihua, Hong, Kunlun, & Omar Diallo, Souleymane. Side chain dynamics in semiconducting polymer MEH-PPV. United States. doi:10.1002/APP.47394.
Osti, Naresh C., Mamontov, Eugene, Daemen, Luke L., Browning, Jim, Keum, Jong K., Ho, Hoi Chun, Chen, Jihua, Hong, Kunlun, and Omar Diallo, Souleymane. 2018. "Side chain dynamics in semiconducting polymer MEH-PPV". United States. doi:10.1002/APP.47394.
@article{osti_1488691,
title = {Side chain dynamics in semiconducting polymer MEH-PPV},
author = {Osti, Naresh C. and Mamontov, Eugene and Daemen, Luke L. and Browning, Jim and Keum, Jong K. and Ho, Hoi Chun and Chen, Jihua and Hong, Kunlun and Omar Diallo, Souleymane},
abstractNote = {We report that the characteristic nanoscale dynamics of the alkyl side groups in the light-emitting polymer poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] have been investigated using quasi-elastic neutron scattering (QENS). The measurements were taken below the polymer's glass transition (T ≤ Tg ≃ 353 K), where the main backbone is in a rigid state and does not contribute to the broadening of the QENS signal. An analytical diffusion model consisting of a static term and two dynamical components, characterizing the flexible side groups, provide an excellent fit to the experimental data. The two observed dynamical processes are all localized in character, with no meaningful dependence on temperature. The faster process, with characteristic timescale of ~18 ps at room temperature (RT), can be linked to the average mobility of the terminal protons of the alkyl chain, while the slower process, with characteristic timescale of ~170 ps at RT, to those protons at the other end of the alkyl chain, closest to the backbone. Lastlyl, while the fraction of mobile protons contributing to the QENS signal increases with increasing temperature, the characteristic timescale and confining volume within which the protons are able to move locally depend chiefly on the polymer conformational state.},
doi = {10.1002/APP.47394},
journal = {Journal of Applied Polymer Science},
number = 0,
volume = 136,
place = {United States},
year = {2018},
month = {12}
}

Works referenced in this record:

The Chemistry of Conducting Polythiophenes
journal, January 1998

Mesoscale Morphology and Charge Transport in Colloidal Networks of Poly(3-hexylthiophene)
journal, May 2011
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  • Macromolecules, Vol. 44, Issue 10, p. 3801-3809
  • DOI: 10.1021/ma2000515