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MULTIFUNCTIONAL CHIRAL POLYMERIC MATERIALS CONTAINING SIDE-CHAIN AZOCARBAZOLE CHROMOPHORES L. Angiolini, L. Giorgini, F. Mauriello Dipartimento di Chimica.

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Presentazione sul tema: "MULTIFUNCTIONAL CHIRAL POLYMERIC MATERIALS CONTAINING SIDE-CHAIN AZOCARBAZOLE CHROMOPHORES L. Angiolini, L. Giorgini, F. Mauriello Dipartimento di Chimica."— Transcript della presentazione:

1 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 Synthesis of materials and characterization Photomodulation optical properties Photoconductive and photorefractive properties A. Golemme, R. Termine Dipartimento di Chimica, University of Calabria

2 PHOTOCHROMIC FUNCTIONALITY POLYMERIC BACKBONE CHIRAL FUNCTIONALITY PHOTOCONDUCTIVE & PHOTOREFRACTIVE FUNCTIONALITY Features of the multifunctional polymer studied  M n =  M w /  M n = 1.8 T g = 147°C T d = 363°C High T g and decomposition temperatures

3 Absorption in the visible: azo-dyes n  *,  * and CT el. trans. Pump at 488 nm Probe at 633 nm ,0 0,5 1,0 1,5 2,0 2,5 Absorbance Wavelength (nm) 488 nm633 nm Carbazole Aromatic of azo-dyes Cis Trans

4 Chiral conformation of one prevailing helical handedness CHIRAL GROUP PHOTOREFRACTIVE GROUP AZO-AROMATIC CHROMOPHORE Potential use as chiroptical switches Excitonic splitting - + Amplified Chirality UV-vis spectra CD spectra

5 Photoconductive and photorefractive materials Holographic Data Storage Electroluminescents Diodes NanolithographyNanolithography Integrals circuits Capacity in bytes Holographic Memories Small Mag.Disks Large Mag. Disks CD ROM Magnetic Tape Floppy disks Access time in milliseconds Security from Forgery Holographic Interferometry Medical Application Phase Conjugation Optical Device Pattern Recognition Optical Amplification Holographic Data Storage 3-D Holovideo

6 Carbazole Chiral group Azobenzene Chiral group Multifunctional monomer Chiral monomer with carbazole Chiral monomer with azobenzene + MULTIFUNCTIONAL COPOLYMERS MULTIFUNCTIONAL OMOPOLYMERS MULTIFUNCTIONAL POLYMERS FOR PHOTONICS AND OPTOELECTRONICS Synthetic approach CarbazoleAzobenzene Multifunctional Polymers Chiral group

7 Multifunctional copolymers synthetized Multifunctional homopolymers synthetized

8 Thickness nm <900 nm Applications as Amorphous thin films obtained by spin-coating Applications as Amorphous thin films obtained by spin-coating

9 Ē  rotational diffusion hh hh STOP trans cis Photoinduced trans  cis  trans isomerization cycles trans

10 LP CP R. Hagen, T. Bieringer Adv. Mater 13, 1805 (2001) Reversible photoinduced orientation of azobenzene groups

11 Write and erase of optical information for OPTICAL STORAGE 1010 Typical experiment of photoinduced birefringence cycles 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, (2006) L. Angiolini, T. Benelli, R. Bozio, A. Daurù, L. Giorgini, D. Pedron, E. Salatelli, Eur. Polym. J, in press (2007)

12 Reversible write and erase of optical information for OPTICAL STORAGE Temporal stability of photoinduced signals Photomodulation of birefringence on Poly[(S)-MLECA] Pump at 488 nm I pump  100 mW/cm 2 Probe at 633 nm I probe < 1 mW/cm 2

13 poly[(S)-MAP-N] T g = 208  C thin films 100  300 nm I  160 mW/cm 2 x 60 s Reversible inversion of the CD signal by irradiation with CP-L and/or CP-R light 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, (2003) L. Angiolini, T. Benelli, R. Bozio, A. Daurù, L. Giorgini, D. Pedron, Synthetic Metals 139, 743 (2003) CHIROPTICAL SWITCHES

14 CP-L CP-R Dipolar interactions Side-chain Chiral groups Azo-aromatic groups CP-L 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) Reversal of the coils or of the domains by irradiating with CP light !?? Reversal of the coils or of the domains by irradiating with CP light !?? CHIROPTICAL SWITCHES

15 Photomodulation of the chiroptical properties of Poly[(S)-MLECA] CHIROPTICAL SWITCHES

16 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. Surface relief gratings (SRGs) photoinduced on Poly[(S)-MLECA]

17 Crossed Surface Relief Gratings SRGs with 1  m periods, in the x and y directions SRGs, with 2  m period, in the x-direction and 1  m period, in the y-direction,

18 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. Combination of the photoinduced chiral orientation and the photoinduced SRG formation. Helicoidal structures (LISH) superimposed to a SRG with a period of about 1  m 5  m Laser Induced Supramolecular Helix (LISH) inscribed on Poly[(S)-MLECA] Laser Induced Supramolecular Helix (LISH) inscribed on Poly[(S)-MLECA]

19 Photoconductivity properties of Poly[(S)-MLECA] 2.3x ScmW -1 at 60V/  m

20

21 Prof. Luigi Angiolini Dr. Tiziana Benelli Dr. Francesco Mauriello Dott. Elisabetta Salatelli Dott. Libero Damen Dott. Gianluca Perfetti Financial support by MIUR (FIRB 2001) and Consorzio INSTM is gratefully acknowledged University of Bologna University of Padova Prof. Renato Bozio Prof. Danilo Pedron Dott. Tiziano Dainese Dott. Alessandro Daurù University of Calabria Prof. Mauro Ghedini Prof. Attilio Golemme Dr. Roberto Termine ACKNOWLEDGEMENTS:ACKNOWLEDGEMENTS: Photomodulation of birefringence, chiroptical switches and SRGs Photoconductivity and Photorefractive properties

22 The author dedicates this work to the memory of Professor Carlo Carlini

23

24 Photomodulation of linear birefringence and dichroism PHOTORESPONSIVE PROPERTIES CONVENTIONAL MATERIALS CHIROPTICAL SWITCHES OPTICAL STORAGE AND CHIROPTICAL SWITCHES CHIRAL PHOTOCHROMIC POLYMERS Photomodulation of chiroptical properties OPTICAL STORAGE

25 Polimero  /I (S cm W -1 ) Campo elettrico (V/mm) Poli[MECSI] 100%1.2 e-1460 Poli[MECP] 80% DPP 20%8.0 e-1140 Poli[MLECA] 100%3.0 e-1440 Poli[MECPS] 85% DPP 15%2.0e-1260

26 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 Financial support by MIUR (PRIN 2001) and Consorzio INSTM is gratefully acknowledged University of Bologna University of Padova

27 poly[(S)-MAP-C] (T g = 192  C), heated at 200  C Heat

28 The application of heat seems to amplify the overall chirality of the system Absorbance Ellipticity (mdeg) Wavelength (nm) poly[(S)-MAP-C] T g = 192  C 230  C 190  C L. Angiolini et al., Synth. Met., 138, (2003) Heat CP-LHeat CP-R

29 poly[(S)-MAP-C] 184 nm I  200 mW/cm 2 x 180 s 1 th - 6 th I  100 mW/cm 2 x 180 s 7 th - 8 th I  50 mW/cm 2 x 180 s 9 th - 10 th Chirality increases with the increase of the tot. fluence L. Angiolini et al., Synth. Met., (2003) in press

30 poly[(S)-MAP-C] 184 nm I  200 mW/cm 2 x 180 s 1 th - 6 th I  100 mW/cm 2 x 180 s 7 th - 8 th I  50 mW/cm 2 x 180 s 9 th - 10 th poly[(R)-MAP-C] 210 nm I  100 mW/cm 2 x 400 s 1 th - 10 th

31 Synthesis of multifunctional monomers Biphasic medium H 2 O/CH 2 Cl 2

32 Modification in shape and intensity of the CD and abs. spectra Photoinduced aggregation? CP-L CP-R

33 poly[(S)-MAP-C] 170 nm I  400 mW/cm 2 x 180 s Temporal and thermal stability Temporal and thermal stability L. Angiolini et al., Synth. Met., in press (2003) Temporal and thermal stability of photoinduced CD signals CP-L CP-R

34 poly[(S)-MAP-N-co-DR1M] 50/50 Film thin 290 nm I  50 mW/cm 2 x 180 s 1 th - 3 th I  100 mW/cm 2 x 180 s 4 h - 7 th I  200 mW/cm 2 x 180 s 8 th - 10 th CHIROPTICAL SWITCHES

35 G. Iftime, et al., J. Am. Chem. Soc. 2000, 122, M. Ivanov, et al., J. Mod. Opt. 2000, 47, 861. After ordering with LP light After ordering with LP light LC smectic-A phase

36 The properties of the materials change by using different co-monomers

37 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

38 Materiali fotorifrattivi Photorefractive material = Photoconducting material +NLO chromophore Effetto fotorifrattivo Molecole organiche coinvolte nel processo

39 Il gruppo carbazolico forma relativamente cationi radicalici stabili (holes) Differenti sostituenti possono essere facilmente introdotti nell’anello carbazoico. Il gruppo carbazolico permette una maggiore coniugazione lungo la catena laterale Materiali contenenti i gruppi carbazolici sono caratterizzati da una elevata stabilità termica e fotochimica Il carbazolo è un intermedio relativamente economico. Scelta gruppo fotoconduttore CarbazoloCarbazolo

40 4 5,2 gh 8,1,6 * a c e,f b d 4 5,2 gh 8,1,6 * a c e,f b d 4 5,2 hg 8,1,6 * a c e,f b d a b Scomparsa del segnale dei protoni del CH 2 metacrilico (S)-MLECA poli[(S)-MLECA] Spettroscopia 1 H-NMR Omopolimero poli[(S)-MLECA]

41 Misure di dicroismo circolare stato solido Potenziali swithes chiroottici couplet eccitonico - + STATO SOLIDO SOLUZIONE Conservazione ordinamento cromofori

42 Misure di fotoconduzione Risultati Preliminari Poly [(S)-MECPS] Poly [(S)-(+)-MECP] PROPRIETA’ FOTOCONDUTTIVE 2 ordini di grandezza maggiore


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