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Single chain versus single aggregate spectroscopy of conjugated polymers. Where is the border?

Lin, Hongzhen LU ; Hania, Ralph LU ; Bloem, Robert; Mirzov, Oleg LU ; Thomsson, Daniel LU and Scheblykin, Ivan LU (2010) In Physical chemistry chemical physics : PCCP 12. p.11770-11777
Abstract
Single chains of conjugated polymers e.g. MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) have become interesting objects for single molecule spectroscopy (SMS) studies. However, most of the experiments so far were performed without full awareness of the isolation status of the polymer chains in host matrices. We used steady-state and time-resolved fluorescence methods and 2D polarization single molecule imaging technique to unravel the isolation/aggregation status of MEH-PPV in spin-coated films prepared at different conditions. It turned out that a sample showing isolated bright spots in fluorescence images could be obtained in a very broad concentration range of MEH-PPV when toluene was used as a solvent and PMMA as... (More)
Single chains of conjugated polymers e.g. MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) have become interesting objects for single molecule spectroscopy (SMS) studies. However, most of the experiments so far were performed without full awareness of the isolation status of the polymer chains in host matrices. We used steady-state and time-resolved fluorescence methods and 2D polarization single molecule imaging technique to unravel the isolation/aggregation status of MEH-PPV in spin-coated films prepared at different conditions. It turned out that a sample showing isolated bright spots in fluorescence images could be obtained in a very broad concentration range of MEH-PPV when toluene was used as a solvent and PMMA as a matrix. If the MEH-PPV concentration was not sufficiently low, a substantial fraction of the fluorescence spots should be assigned to individual nano-aggregates rather than truly isolated chains of the polymer. Contrary to single aggregates, truly isolated MEH-PPV chains showed blue-shifted emission spectra, mono-exponential fluorescence decay dynamics with relatively long lifetimes (0.4-1.2 ns), and high polarization anisotropy. We argue that insufficient control of the concentration in the published SMS studies of MEH-PPV resulted in incorrect assigning of some spectroscopic properties of single aggregates to isolated MEH-PPV chains. We believe this to be the main origin of discrepancies among the published data in this field. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical chemistry chemical physics : PCCP
volume
12
pages
11770 - 11777
publisher
Royal Society of Chemistry
external identifiers
  • wos:000281726800067
  • pmid:20694242
  • scopus:77956505293
ISSN
1463-9084
DOI
10.1039/c001120g
language
English
LU publication?
yes
id
d21ec41f-1be2-4015-9db1-8ceb71f282f2 (old id 1665442)
date added to LUP
2010-09-10 14:04:06
date last changed
2018-07-08 03:38:43
@article{d21ec41f-1be2-4015-9db1-8ceb71f282f2,
  abstract     = {Single chains of conjugated polymers e.g. MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) have become interesting objects for single molecule spectroscopy (SMS) studies. However, most of the experiments so far were performed without full awareness of the isolation status of the polymer chains in host matrices. We used steady-state and time-resolved fluorescence methods and 2D polarization single molecule imaging technique to unravel the isolation/aggregation status of MEH-PPV in spin-coated films prepared at different conditions. It turned out that a sample showing isolated bright spots in fluorescence images could be obtained in a very broad concentration range of MEH-PPV when toluene was used as a solvent and PMMA as a matrix. If the MEH-PPV concentration was not sufficiently low, a substantial fraction of the fluorescence spots should be assigned to individual nano-aggregates rather than truly isolated chains of the polymer. Contrary to single aggregates, truly isolated MEH-PPV chains showed blue-shifted emission spectra, mono-exponential fluorescence decay dynamics with relatively long lifetimes (0.4-1.2 ns), and high polarization anisotropy. We argue that insufficient control of the concentration in the published SMS studies of MEH-PPV resulted in incorrect assigning of some spectroscopic properties of single aggregates to isolated MEH-PPV chains. We believe this to be the main origin of discrepancies among the published data in this field.},
  author       = {Lin, Hongzhen and Hania, Ralph and Bloem, Robert and Mirzov, Oleg and Thomsson, Daniel and Scheblykin, Ivan},
  issn         = {1463-9084},
  language     = {eng},
  pages        = {11770--11777},
  publisher    = {Royal Society of Chemistry},
  series       = {Physical chemistry chemical physics : PCCP},
  title        = {Single chain versus single aggregate spectroscopy of conjugated polymers. Where is the border?},
  url          = {http://dx.doi.org/10.1039/c001120g},
  volume       = {12},
  year         = {2010},
}