MULTIFUNCTIONAL CHIRAL POLYMERIC
MATERIALS CONTAINING SIDE-CHAIN
AZOCARBAZOLE CHROMOPHORES
L. Angiolini, L. Giorgini, F. Mauriello
Dipartimento di Chimica Industriale e dei Materiali, University of Bologna
R. Bozio, T. Dainese, D. Pedron
Dipartimento di Scienze Chimiche, University of Padova
A. Golemme, R. Termine
Dipartimento di Chimica, University of Calabria
Synthesis of materials and characterization
Photomodulation optical properties
Photoconductive and photorefractive properties
Features of the multifunctional polymer studied
CH3
(CH2
POLYMERIC
BACKBONE
C) n
C O
Mn = 13400
O
* CH
C
CH3
CHIRAL
FUNCTIONALITY
O
Mw /Mn = 1.8
Tg = 147°C
O
PHOTOCONDUCTIVE &
PHOTOREFRACTIVE
FUNCTIONALITY
N
N
N
CN
PHOTOCHROMIC
FUNCTIONALITY
Poly[(S)-MLECA]
Td = 363°C
High Tg and
decomposition
temperatures
Carbazole
Aromatic of azo-dyes
488 nm
633 nm
2,5
Absorbance
2,0
Trans
1,5
1,0
0,5
0,0
200
300
400
500
600
Wavelength (nm)
Absorption in the visible:
azo-dyes n *, * and CT el. trans.
Pump at 488 nm
Probe at 633 nm
Cis
Chiral conformation of one prevailing helical handedness
0,6
Amplified Chirality
(S)-MLECA
Poli[(S)-MLECA]
0,5
+
0,3
-1
-1
(L mol cm )
0,4
CD spectra
0,2
0,1
0,0
-0,1
Excitonic splitting
-
-0,2
25000
UV-vis spectra
-1
-1
 (L mol cm )
20000
15000
CHIRAL GROUP
PHOTOREFRACTIVE GROUP
AZO-AROMATIC CHROMOPHORE
10000
5000
0
300
400
 (nm)
500
600
Potential use as
chiroptical switches
•Security from Forgery
•Holographic Interferometry
• Medical Application
•Phase Conjugation
•Optical Device
•Pattern Recognition
Holographic Data Storage
Access time in milliseconds
Photoconductive and photorefractive materials
104
102
CD ROM
Floppy disks
101
Small Mag.Disks
Large Mag.
Disks
100
• Optical Amplification
10-1
• Holographic Data Storage
10-2
Holographic Memories
106
• 3-D Holovideo
Nanolithography
Magnetic Tape
103
Electroluminescents Diodes
107 108 109 1010 1011 1012
Capacity in bytes
Integrals circuits
MULTIFUNCTIONAL POLYMERS FOR PHOTONICS AND
OPTOELECTRONICS
Carbazole
N
Chiral group
Azobenzene
Synthetic approach
Multifunctional Polymers
Chiral group
Carbazole
Chiral monomer
with carbazole
+
Azobenzene
Chiral group
MULTIFUNCTIONAL
COPOLYMERS
Chiral monomer
with azobenzene
Multifunctional
monomer
MULTIFUNCTIONAL
OMOPOLYMERS
Multifunctional copolymers synthetized
CH3
(CH 2
CH3
CH3
(CH 2
C) x
C O
(CH2
C)
1-x
C O
O
O
C O
C)
1-x
C O
O
O
C) x
CH3
CH3
(CH2
O
O
N
N
O
O
O
N
N
N
N
N
N
N
N
N
N
N
poly[(S)-(+)-MECSI]
poliy(S)-(+)-MECSI-co-(S)-(+)-MOSI](75/25)
poli[yS)-(+)-MECSI-co-(S)-(+)-MOSI](50/50)
poli[yS)-(+)-MECSI-co-(S)-(+)-MOSI](25/75)
x=1
x=0.75
x=0.50
x=0.25
NO2
R
x =1
x = 0.50
N
O
N
CH3
(CH2
O
O
C) x
C O
O
*
N
Multifunctional
homopolymers
synthetized
N
* CH CH3
C O
O
N
N N
poly[(S)-MCAPP-C]
O
poly[(S)-MCPS]
n=1
poly[(S)-MCPS-co-(S)-MOSI] n=0.50
poly[(S)-MCPP]
n=1
poly[(S)-MCPP-co-(S)-MAP-C] n=0.50
poly[(S)-MCPP-co-(S)-MAP-N] n=0.50
C )n
C
O
N
CH 3
( CH2
N
*
N
N
O
*
O
N
Poly[(S)-(-)-MECP]
Poliy(S)-(-)-MECP-co-(S)-MAP-N]
O
O
*
*
*
CH3
( CH2 C )n ( CH2 C )1-n
C O
C O
( CH2 C )n ( CH2 C )1-n
C O
C O
*
*
CH3
CH3
N N
R
poly[(S)-MLECA]
CN
Applications as
Amorphous thin films obtained by spin-coating
Thickness 100-400 nm
<900 nm
Photoinduced trans  cis  trans isomerization cycles
trans
trans
N
cis
h
N
N
N
Ē
rotational
diffusion
N
N

h
N
N
STOP
Reversible photoinduced orientation of azobenzene groups
Linear Pol.
Circular Pol.
LP
CP
R. Hagen, T. Bieringer Adv. Mater 13, 1805 (2001)
Typical experiment of photoinduced birefringence cycles
n1
0,14
0,08
0,06
0,04
0,02
0
0,00
30
60
with LP light
0,10
Write and erase of
optical information for
OPTICAL STORAGE
with CP light
n2
Irradiation
n
0,12
Irradiation
1
Birefringence
90 120 150 180 210 240 270 300 330
Time (s)
L. Angiolini, R. Bozio, L. Giorgini, D. Pedron, G. Turco, A. Daurù, Chem. Eur. J.,
8, 4241 (2002)
L. Angiolini, T. Benelli, R. Bozio, A. Daurù, L. Giorgini, D. Pedron, E. Salatelli,
Macromolecules, 39, 489-497 (2006)
L. Angiolini, T. Benelli, R. Bozio, A. Daurù, L. Giorgini, D. Pedron, E. Salatelli, Eur.
Polym. J, in press (2007)
Photomodulation of birefringence on Poly[(S)-MLECA]
Reversible
write and erase of
optical information for
OPTICAL STORAGE
Temporal stability
of photoinduced signals
Pump at 488 nm Ipump  100 mW/cm2
Probe at 633 nm Iprobe < 1 mW/cm2
CHIROPTICAL SWITCHES
Native
Irr. CP-L light
Irr. CP-R light
0,15
Ellipticity [mdeg/nm]
0,10
Reversible inversion
of the CD signal by
irradiation with CP-L
and/or CP-R light
0,05
0,00
-0,05
-0,10
-0,15
350
400
450
500
550
600
Wavelength [nm]
poly[(S)-MAP-N] Tg = 208 C
thin films 100  300 nm
I  160 mW/cm2 x 60 s
650
Ellipticity at 470 nm (mdeg)
-0,20
300
CP-R irradiation
150
100
Native
50
0
-50
-100
-150
CP-L irradiation
0
50
150
100
2
Fluence (J/cm )
L. Angiolini, R. Bozio, L. Giorgini, D. Pedron, G. Turco, A. Daurù, Chem. Eur. J., 8, 4241 (2002)
L. Angiolini, R. Bozio, L. Giorgini, D. Pedron, Synth. Met., 138, 375-379 (2003)
L. Angiolini, T. Benelli, R. Bozio, A. Daurù, L. Giorgini, D. Pedron, Synthetic Metals 139, 743 (2003)
200
Reversal of the coils or of the domains
by irradiating with CP light !??
CHIROPTICAL
SWITCHES
CP-L
CP-R
CP-L
Dipolar interactions
Side-chain
Chiral groups
Azo-aromatic groups
CP-R
L. Angiolini, T. Benelli, L. Giorgini, A. Painelli, F. Terenziani, Chem. Eur. J. (2005)
L. Angiolini, T. Benelli, L. Giorgini, E. Salatelli, Polymer, 46, 2424 (2005)
L. Angiolini, T. Benelli, L. Giorgini, E. Salatelli, Polymer, 47, 1875–1885 (2006)
Photomodulation of the chiroptical properties of
Poly[(S)-MLECA]
CHIROPTICAL
SWITCHES
Surface relief gratings (SRGs) photoinduced on
Poly[(S)-MLECA]
Irradiation of azo polymer films with an interference
pattern for a period of time longer than that required for
photoinduced orientation produces a modification of the
film surface.
Crossed Surface Relief Gratings
SRGs, with 2 mm period, in the x-direction
and 1 mm period, in the y-direction,
SRGs with 1mm periods, in the x and y directions
Laser Induced Supramolecular Helix (LISH)
inscribed on Poly[(S)-MLECA]
Unusual superhelix-like (LISH)
patterns can be directly
photofabricated on the surface of
azo polymer films by a
interference pattern obtained by
EP-L (ellipticity = 0.4) and
EP-R (ellipticity < 0.4) light.
5 mm
Combination of the photoinduced
chiral orientation and the
photoinduced SRG formation.
Helicoidal structures (LISH) superimposed to a SRG with a period of about 1mm
Photoconductivity properties of Poly[(S)-MLECA]
2.3x10-13 ScmW-1
at 60V/mm
ACKNOWLEDGEMENTS:
Prof. Luigi Angiolini
Dr. Tiziana Benelli
Dr. Francesco Mauriello
Dott. Elisabetta Salatelli
Dott. Libero Damen
Dott. Gianluca Perfetti
University of Bologna
Prof. Renato Bozio
Prof. Danilo Pedron
Dott. Tiziano Dainese
Dott. Alessandro Daurù
University of Padova
Prof. Mauro Ghedini
Prof. Attilio Golemme
Dr. Roberto Termine
University of Calabria
Photomodulation of birefringence,
chiroptical switches and SRGs
Photoconductivity and Photorefractive
properties
Financial support by MIUR (FIRB 2001) and Consorzio INSTM is gratefully acknowledged
The author dedicates this work
to the memory of
Professor Carlo Carlini
PHOTORESPONSIVE
PROPERTIES
Photomodulation of linear
birefringence and
dichroism
CONVENTIONAL
MATERIALS
OPTICAL
STORAGE
CHIRAL
PHOTOCHROMIC
POLYMERS
OPTICAL
STORAGE
AND
CHIROPTICAL
SWITCHES
Photomodulation of
chiroptical properties
CHIROPTICAL
SWITCHES
s/I (S cm W-1)
Campo elettrico
(V/mm)
Poli[MECSI] 100%
1.2 e-14
60
Poli[MECP] 80% DPP 20%
8.0 e-11
40
Poli[MLECA] 100%
3.0 e-14
40
Poli[MECPS] 85% DPP 15%
2.0e-12
60
Polimero
ACKNOWLEDGEMENTS:
Dr. Tiziana Benelli
Dr. Daniele Caretti
Dr. Elisabetta Salatelli
Dr. Delio Alfino
Dr. Saverio Cazzoli
Dr. Ada delle Donne
Mr. Marco Toto
Dr. Alessandro Daurù
Dr. Giovanni Turco
Mr. Andrea Barbiero
University of Bologna
University of Padova
Financial support by MIUR (PRIN 2001) and Consorzio
INSTM is gratefully acknowledged
poly[(S)-MAP-C] (Tg = 192 C), heated at 200 C
Ellipticity (mdegree)
800
native
5 min
10 min
15 min
20 min
25 min
30 min
40 min
50 min
60 min
75 min
100 min
115 min
130 min
600
400
200
0
-200
-400
-600
200
300
400
500
wavelenght (nm)
600
700
Heat
The application of heat seems to amplify the overall chirality of the system
Ellipticity (mdeg)
40
190 C
20
0
-20
CP-L
-40
Heat
230 C
CP-R
-60
Absorbance
poly[(S)-MAP-C] Tg = 192 C
2
Heat
1
0
250
350
450
550
Wavelength (nm)
L. Angiolini et al., Synth. Met., 138, 375-379 (2003)
150
o
8 CP-R
o
o
6 and 10 CP-R
o
4 CP-R
o
2 CP-R
50
Chirality increases
with the increase
of the tot. fluence
0
o
1 CP-L
o
3 CP-L
o
5 CP-L
o
o
7 and 9 CP-L
-50
-100
-150
250
Native
300
350
400
450
500
Wavelegth [nm]
poly[(S)-MAP-C] 184 nm
I  200 mW/cm2 x 180 s 1th - 6th
I  100 mW/cm2 x 180 s 7th - 8th
I  50 mW/cm2 x 180 s 9th - 10th
550
600
650
Ellipticity at 470 nm (mdeg)
Ellipticity [mdeg]
100
CP-R irradiation
150
100
Native
50
0
-50
-100
CP-L irradiation
-150
0
50
100
150
200
2
L. Angiolini et al., Synth. Met., (2003) in press
Fluence (J/cm )
250
300
150
o
8 CP-R
o
o
6 and 10 CP-R
o
4 CP-R
o
2 CP-R
Ellipticity [mdeg]
100
50
0
o
1 CP-L
o
3 CP-L
o
5 CP-L
o
o
7 and 9 CP-L
-50
Native
-100
-150
250
300
350
400
450
500
550
600
poly[(S)-MAP-C] 184 nm
I  200 mW/cm2 x 180 s 1th - 6th
I  100 mW/cm2 x 180 s 7th - 8th
I  50 mW/cm2 x 180 s 9th - 10th
650
Wavelegth [nm]
o
9 CP-R
o
7 CP-R
o
5 CP-R
o
3 CP-R
o
1 CP-R
Ellipticity [mdeg/nm]
0,6
0,4
Native
0,2
0,0
poly[(R)-MAP-C] 210 nm
I  100 mW/cm2 x 400 s 1th - 10th
-0,2
o
2 CP-L
o
4 CP-L
o
6 CP-L
o
8 CP-L
o
10 CP-L
-0,4
-0,6
-0,8
300
400
500
Wavelegth [nm]
600
Synthesis of multifunctional monomers
OH
OH
N
N
+ N2+
CN
N N
HECA
CH 3
CH 2
CN
CH3
C
CH2
C
C O
C O
O
O
* CH CH 3
* CH CH3
C O
C O
O
OH
DPTS
DIPC
Biphasic medium
H2O/CH2Cl2
O
CH3(CH2)10CH2O
N
N N
CN
(S)-MLECA
O
S
ONa
150
o
8 CP-R
50
Photoinduced aggregation?
0
-50
Native
-100
o
9 CP-L
-150
250
300
350
400
450
500
550
600
650
Wavelength [nm]
Native
After 10 irr. CP-L/CP-R
1,6
1,2
Absorbance
Ellipticity [mdeg]
100
Modification in shape
and intensity of the
CD and abs. spectra
0,8
CP-L
0,4
0,0
200
300
400
500
Wavelegth [nm]
600
700
CP-R
Temporal and thermal stability of photoinduced CD signals
poly[(S)-MAP-C] 170 nm
I  400 mW/cm2 x 180 s
Native
Irr. CP-L
After heating
After 1 year
Ellipticity (mdeg)
50
0
CP-L
CP-R
-50
300
400
500
Wavelength (nm)
Temporal and thermal
stability
L. Angiolini et al., Synth. Met., in press (2003)
150
o
8 CP-R
o
o
6 and 10 CP-R
o
4 CP-R
o
2 CP-R
50
CHIROPTICAL
SWITCHES
0
o
1 CP-L
o
3 CP-L
o
5 CP-L
o
o
7 and 9 CP-L
-50
-100
-150
250
Native
300
350
400
450
500
550
600
650
CP-R irradiation
Wavelegth [nm]
poly[(S)-MAP-N-co-DR1M] 50/50
Film thin 290 nm
I  50 mW/cm2 x 180 s 1th - 3th
I  100 mW/cm2 x 180 s 4h - 7th
I  200 mW/cm2 x 180 s 8th - 10th
Ellipticity at 470 nm (mdeg)
Ellipticity [mdeg]
100
150
100
Native
50
0
-50
-100
-150
CP-L irradiation
0
50
100
150
2
Fluence (J/cm )
200
M. Ivanov, et al.,
J. Mod. Opt. 2000, 47, 861.
After ordering with
LP light
LC smectic-A phase
G. Iftime, et al., J. Am. Chem. Soc. 2000, 122, 12646.
The properties of the materials change by using different co-monomers
CH3
( CH2
poly[(S)-MAP-N]
0,25
poly[(S)-MAP-N-co-DR1M] 75/25
B
C
C
0,10
0,05
D
A
Birefringence, n
0,15
)
C
C O
C O
O
O
1-x
C
N
B
0,15
B
N
B
0,10
D
D
D
0,05
A
N
A
0,00
0,00
60
x
( CH2
*
C
0,20
30
CH3
)
0,25
0,20
Birefringence, n
H
C
A
90 120 150 180 210 240 270 300
Time (sec)
0
N
N
N
NO2
NO2
200 400 600 800 1000 1200 1400 1600
Time (sec)
0,25
0,25
poly[(S)-MAP-N-co-DR1M] 50/50
0,15
B
0,10
B C
B C
C
BC
0,05
D
0,00
A
A
0
D
50
D
D
B
0,10
B
C
B
C
0,05
0
A
A
A
100 150 200 250 300 350 400
50
C
D
D
D
DR1M
poly[(S)-MAP-N]
poly[(S)-MAP-N-co-DR1M]75/25
poly[(S)-MAP-N-co-DR1M]50/50
poly[(S)-MAP-N-co-DR1M]25/75
poy[(S)-MAP-N-co-DR1M]10/90
poly[DR1M]
0,15
0,00
A
A
(S)-MAP-N
poly[(S)-MAP-N-co-DR1M] 25/75
0,20
Birefringence, n
Birefringence, n
0,20
x=1
x=0.75
x=0.50
x=0.25
x=0.10
x=0
100 150 200 250 300 350 400
Time (sec)
Time (sec)
0,25
0,25
poly[DR1M]
0,10
B
C
0,05
B
0,15
C
0,10
0,05
D
20
0,15
poly[DR1M]
0,10
0,00
A
0
poly[(S)-MAP-N]
A
D
0,00
Birefringence, n
0,15
0,20
0,20
Birefringence, n
Birefringence, n
0,20
0,25
poly[(S)-MAP-N-co-DR1M] 10/90
40
60
80 100 120 140 160 180
Time (sec)
30
60
90 120 150 180 210 240 270 300
Time (sec)
0,05
0,0
0,2
0,4
0,6
0,8
Mole fraction of (S)-MAP-N units
1,0
Materiali fotorifrattivi
Effetto fotorifrattivo
DEFINIZIONE:
L’effetto
fotorifrattivo
(PRe)
si
riferisce alla modulazione
spaziale dell’indice di
rifrazione generato da un
meccanismo specifico: la
ridistribuzione fotoindotta
di carica in un materiale
nel quale l’indice di
rifrazione dipende dal
campo elettrico applicato.
I processi fisici legati al
meccanismo fotorifrattivo sono:
1.Assorbimento della radiazione
luminosa con generazione di
cariche
2.Trasporto delle cariche
3.Intrappolamento delle cariche
4.Generazione di un campo
elettrico interno
5.Riorientazione molecolare
interna con variazione dell’indice di
rifrazione
Materiali fotorifrattivi
Effetto fotorifrattivo
Molecole organiche
coinvolte nel processo
Densità di carica
ilibera
Trasporto carica
Densità di carica
intrappolata
Intensità luce
Generazione carica
Intrappolamento carica
Campo spaziale
di carica: indice
di rifrazione di
carica n
Indice Modulazione Elettro-ottica
Photorefractive material =
Photoconducting material
+NLO chromophore
Ioni
Immobili
Hole
mobili
Hole
Intrappolati
Scelta gruppo fotoconduttore
Carbazolo
Il gruppo carbazolico forma relativamente cationi radicalici stabili (holes)
Il carbazolo è un intermedio relativamente economico.
Differenti sostituenti possono essere facilmente introdotti nell’anello carbazoico.
Materiali contenenti i gruppi carbazolici sono caratterizzati da una elevata
stabilità termica e fotochimica
Il gruppo carbazolico permette una maggiore coniugazione lungo la catena
laterale
Spettroscopia 1H-NMR
Omopolimero poli[(S)-MLECA]
d
(S)-MLECA
b
b
a
CH3
CH2
C
h
h
g g
**
C O
c
O
H C * CH3
4
8,1,6
5,2
e,f
a
c
d
a
C O
O
poli[(S)-MLECA]
e
f
8
7
N
1
6
5
4
(S)-MLECA
Scomparsa del
segnale dei protoni
del CH2 metacrilico
2
3
N N
g
h
CN
b
d
Misure di dicroismo circolare stato solido
6
SOLUZIONE
Ellipticity (mdegree)
4
STATO SOLIDO
2
+
0
-
couplet eccitonico
Conservazione ordinamento
cromofori
2,5
Absorbance
2,0
1,5
Potenziali swithes chiroottici
1,0
0,5
0,0
200
300
400
Wavelength (nm)
500
600
Misure di fotoconduzione
Risultati Preliminari
CH3
C )n
C O
CH3
O
N
N
-1
*
O
-12
2,0x10
-12
1,5x10
-12
1,0x10
-12
BO 08 zona 4 15 settembre 2006
( CH2
polimero 4 85%
DPP
15%
C
O
O
*
O
5,0x10
C )n
N
O
 = 533 nm
-13
0
-11
7,0x10
-11
6,0x10
-11
5,0x10
-11
4,0x10
-11
3,0x10
-11
2,0x10
-11
1,0x10
-11
MECP 80%
DDP 20%
N
5 10 15 20 25 30 35 40 45 50 55 60 65 70
Electric Field (V/mm)
Poly [(S)-MECPS]
 = 533 nm
-1
 = 386 cm
0,0
-1
 = 118 cm
0,0
-1
2,5x10
sph/I (ScmW )
O
8,0x10
sph/I (ScmW )
( CH2
Poly [(S)-(+)-MECP]
PROPRIETA’
FOTOCONDUTTIVE
2 ordini di grandezza maggiore
0
5
10
15
20
25
30
35
Electric Field (V/mm)
40
45