poster carbazole-polyaniline composites
DESCRIPTION
Poster presented at Frontiers in Polymer Science 2009.TRANSCRIPT
260 280 300 320 340 360 380 400 4200
2x105
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1x106
Inte
nsity
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.uni
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Wavelength (nm)360 380 400 420 440 460 480 500 520 540
0
2x105
4x105
6x105
8x105
1x106
Inte
nsity
(arb
.uni
ts)
Wavelength (nm)
440 460 480 500 520 5400
5x104
1x105
2x105
2x105
3x105
Inte
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Wavelength (nm)260 280 300 320 340 360 380 400 420 440
0
1x105
2x105
3x105
4x105
5x105
Inte
nsity
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Wavelength (nm)300 400 500 600 700 800 900
0.6
1.2
1.8
Abso
rban
ce(a
rb.u
nits
)
Wavelength (nm)
300 400 500 600 700 800 900
0.6
1.2
1.8
Abso
rban
ce(a
rb.u
nits
)
Wavelength (nm)
Fluorescent, water dispersible polyaniline and its composites with carbon nanotubes
Pablo Jiménez*, Wolfgang K. Maser, M. Teresa Martinez, Ana M. Benito
PANI / MWNT water dispersable
composites1
Water dispersable, nanostructured PANI
(nf-PANI)
Introduction of carbazole moietiesSynthesis
Copolymerizationwith aniline
Fluorescentproducts
Fluorescent polymers (and MWNT composites)
Mixtures of PANI and fluorescent molecules
Fluorescence due to carbazole moiety inside PANI chain
- Stable & fluorescent water dispersions -
Why they do not copolymerize?
HN
H2N NH2
N
H2N NH2
N
H2N NH2
O
N
NH2
NH2
N
NO2O2N
HN
NO2O2N
N
NO2O2N
O
HN
N
PANI-ADAC
PANI-EDAC
PANI-EAC
PANI-DAC
Introduction
Conclusions
MWNTs have a quenchingeffect on fluorescence
Polyanilines (PANI) are a singular class of conducting polymer since they are susceptible of both acid and redox doping reactions and they present an enviromentally stable conducting state (emeraldine salt)*. Nanostructured polyaniline recentlyemerged as a new kind of material, that combines the benefits of nanomaterials with an easy and low-cost production. Among them PANI nanofibers stand out becouse its simple, template-free synthesis, and its high water dispersability. In thiswork we present some attempts to introduce fluorescence in PANI, via copolymerization with carbazole derived compounds
In the same conditions that generate nanofibrillar PANI, we performed oxidative polymerizations of aniline in presence of various carbazole derivatives. Only in thecase of 3,6-diaminocarbazole a true copolymer (PANI-DAC) was obtained. Copolymers at different ‘carbazole’proportions were synthesized, and they showed a blue emission in fluorescence due to carbazole moieties. Our synthetic conditions enabled us to prepare PANI-DAC and (PANI-DAC)/MWNT composites with a goodwater dispersability.
(NH4)S2O8
NR
H2N NH
N
H2N NH
N
N NH
vs.
phenazine-type oligomer
Hypothesis: in the oxidativereaction media DAC is more proneto give oxidized products similar tothe phenazine-like molecules that
are supposed be formed in the firststages of PANI formation. In fact, DAC reduces greatly the induction
period of polymerizations.
Oxidized aminocarbazoles:
(commercially available)
(previous work)
Instituto de Carboquímica (CSIC), Dept. of NanotechnologyMiguel Luesma Castán 4, E-50018 Zaragoza, Spain
*e-mail: [email protected]
pH=
2pH
= 5
UV-Vis Excitation spectra Emission spectra
em= 450 nm
em= 450 nm
exc= 313 nm
exc= 400 nm
Oxidativepolymerization in
acidic media (HCl 1M)
440 460 480 500 5200
1x105
Inte
nsity
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Wavelength (nm)Acknowledgements
200:1100:166:13:1
aniline:DAC ratio
Fluorescence in copolymer aqueousdispersions increases with ‘carbazole’
content, and it depends strongly on the pH
PANI-DAC/MWNTs
PANI-DAC
NH
HN
NH
HN
n
NH
HN
NH
HN
n
‘polaron’ form
‘bipolaron’ form
*Polyaniline, in emeraldine salt state:
1 Jiménez, P.; Maser, W. K.; Castell, P.; Martínez, M. T.; Benito, A. M. Macromolecular Rapid Communications 2009, 30 (6), 418-422
Zn, HCl
MeOH
Zn, HCl
MeOH
Zn, HCl
MeOH
1. Cu(NO3)2, Ac2O/AcOH
2. NaOH(aq)
Cu(NO 3) 2
Ac 2O/AcOH
Cu(NO 3
) 2Ac 2O
/AcO
H
445 nm
λ λ
λ
λ
Spanish MICINN under projects MAT2006-13167-C02-02 and MAT2007-66927-C02-01).Aragon Consolidated Group Programme DGA-T66 CNN and Aragon Project DGA-PI086/08.P. Jiménez acknowledges Fundación Ramón Areces for his PhD grant
Thorough washing of materials with organic solventsleaves pure PANI-ES and removes all fluorescence