5
414 Aerts et al.
Macromolecules, Vol. 37, No. 14, 2004
to monomer emission cannot yet be excluded, taking into
account the small red shift between monomer and
excimer spectra. This possibility of monomer emission
upon excimer dissociation deserves further investiga-
tion. The faster initial decay of EL-TMSt-25 is unex-
pected, as it is in contrast with the observed slow initial
decay seen for both TMSt and DL-TMSt-25 in solution
and film.
(12) Song, X. D.; Geiger, C.; Leinhos, U.; Perlstein, J .; Whitten,
D. G. J . Am. Chem. Soc. 1994, 116, 10340-10341.
(
(
(
(
(
(
13) Catalan, J .; Zimanyi, L.; Saltiel, J . J . Am. Chem. Soc. 2000,
1
22, 2377-2378.
14) Song, X. D.; Geiger, C.; Farahat, M.; Perlstein, J .; Whitten,
D. G. J . Am. Chem. Soc. 1997, 119, 12481-12491.
15) Song, X. D.; Geiger, C.; Furman, I.; Whitten, D. G. J . Am.
Chem. Soc. 1994, 116, 4103-4104.
16) Letsinger, R. L.; Wu, T. F. J . Am. Chem. Soc. 1994, 116, 811-
8
12.
17) Letsinger, R. L.; Wu, T. F. J . Am. Chem. Soc. 1995, 117,
7323-7328.
4
. Con clu sion s
18) Simeonov, A.; Matsushita, M.; J uban, E. A.; Thompson, E.
H. Z.; Hoffman, T. Z.; Beuscher, A. E.; Taylor, M. J .;
Wirsching, P.; Rettig, W.; McCusker, J . K.; Stevens, R. C.;
Millar, D. P.; Schultz, P. G.; Lerner, R. A.; J anda, K. D.
Science 2000, 290, 307-313.
We have successfully synthesized four series of ran-
dom graft copolymers based on polystyrene in which the
attached stilbene groups keep their chromophoric prop-
erties in solution. The properties of these new materials
are compared with blends containing a set of model
compounds in PS. Films prepared from these materials
show a variety of optical characteristics which allow an
understanding of their aggregate and excimer forming
properties. In blends containing 4-methoxystilbene (MSt),
the formation of crystallites is observed starting from
(
19) Anger, I.; Sandros, K.; Sundahl, M.; Wennerstrom, O. J . Phys.
Chem. 1993, 97, 1920-1923.
(20) Tanner, D.; Wennerstrom, O. Tetrahedron Lett. 1981, 22,
2
313-2316.
(
21) Bazan, G. C.; Oldham, W. J .; Lachicotte, R. J .; Tretiak, S.;
Chernyak, V.; Mukamel, S. J . Am. Chem. Soc. 1998, 120,
9
188-9204.
(22) Oldham, W. J .; Miao, Y. J .; Lachicotte, R. J .; Bazan, G. C. J .
Am. Chem. Soc. 1998, 120, 419-420.
1
5 mol %, which dominates the absorption spectra at
(
23) Altomare, A.; Carlini, C.; Ciardelli, F.; Solaro, R.; Houben,
J . L.; Rosato, N. Polymer 1983, 24, 95-100.
higher concentrations, while 3,4,5-trimethoxy-4′-methyl-
stilbene (TMSt) forms uniform blends up to the highest
loading. The grafts derived from this compound (EL-
MSt-x) and from stilbene (DL-St-x) show the ground-
state interaction to a lesser extent, and their emission
drops with concentration as excimers are formed upon
excitation. Grafts and blends derived from 3,4,5-tri-
methoxy-4′-methylstilbene (TMSt) generally have a
higher PL quantum yield at low concentration. The
direct linked graft based on the latter compound was
found to be superior to the ether-linked one, as the
excimer emission could be strongly reduced, depending
on the solvent used for spin-coating. These materials,
all based on stilbene, span a wide range with respect to
their aggregate- and excimer-forming capabilities, and
they offer new possibilities for the fabrication of near-
UV organic light-emitting diodes as such or as a host
for blue light-emitting oligomer-based devices.
(
24) Ciardelli, F.; Carlini, C.; Solaro, R.; Altomare, A.; Pieroni,
O.; Houben, J . L.; Fissi, A. Pure Appl. Chem. 1984, 56, 329-
342.
(
25) Altomare, A.; Carlini, C.; Ciardelli, F.; Panattoni, M.; Solaro,
R.; Houben, J . L. Macromolecules 1985, 18, 729-734.
26) Tang, C. W.; Vanslyke, S. A. Appl. Phys. Lett. 1987, 51, 913-
(
9
15.
(27) Braun, D.; Heeger, A. J . Appl. Phys. Lett. 1991, 58, 1982-
984.
28) Martin, R. E.; Diederich, F. Angew. Chem., Int. Ed. 1999, 38,
350-1377.
1
(
(
1
29) J ohnson, G. E. J . Chem. Phys. 1975, 62, 4697-4709.
(30) Greiner, A.; Bolle, B.; Hesemann, P.; Oberski, J . M.; Sander,
R. Macromol. Chem. Phys. 1996, 197, 113-134.
(
31) Lee, J . K.; Schrock, R. R.; Baigent, D. R.; Friend, R. H.
Macromolecules 1995, 28, 1966-1971.
(
32) Hochfilzer, C.; Tasch, S.; Winkler, B.; Huslage, J .; Leising,
G. Synth. Met. 1997, 85, 1271-1272.
(33) Aguiar, M.; Akcelrud, L.; Karasz, F. E. Synth. Met. 1995, 71,
2
187-2188.
(
(
(
(
34) Aguiar, M.; Karasz, F. E.; Akcelrud, L. Macromolecules 1995,
2
8, 4598-4602.
Ack n ow led gm en t. C.W. thanks the Institute for the
Promotion of Innovation by Science and Technology in
Flanders (IWT) for a predoctoral grant. The authors
gratefully acknowledge support by the Flemish Govern-
ment in the Concerted Action GOA 99/3/34. Partial
support was provided in the framework of the group
project G.0041.01N by the Flemish Fund for Scientific
Research (FWO).
35) Aguiar, M.; Hu, B.; Karasz, F. E.; Akcelrud, L. Macromol.
Chem. Phys. 1998, 199, 1255-1261.
36) Aguiar, M.; Hu, B.; Karasz, F. E.; Akcelrud, L. Macromol-
ecules 1996, 29, 3161-3166.
37) Aguiar, M.; Akcelrud, L.; Pinto, M. R.; Atvars, T. D. Z.;
Karasz, F. E.; Saltiel, J . J . Photosci. 2003, 10, 149-155.
(38) TranCong, Q.; Ohta, T.; Urakawa, O. Phys. Rev. E 1997, 56,
R59-R62.
(
39) Ohta, T.; Urakawa, O.; Tran-Cong, Q. Macromolecules 1998,
3
1, 6845-6854.
(
40) McKinsey, D. N.; Brome, C. R.; Butterworth, J . S.; Golub,
R.; Habicht, K.; Huffman, P. R.; Lamoreaux, S. K.; Mattoni,
C. E. H.; Doyle, J . M. Nucl. Instrum. Methods Phys. Res. Sect.
B: Beam Interact. Mater. Atoms 1997, 132, 351-358.
Refer en ces a n d Notes
(
(
(
1) Hochstrasser, R. M. Pure Appl. Chem. 1980, 52, 2683-2691.
2) Waldeck, D. H. Chem. Rev. 1991, 91, 415-436.
(
(
(
(
(
41) Gardecki, J . A.; Maroncelli, M. Appl. Spectrosc. 1998, 52,
3) Hamaguchi, H.; Iwata, K. Bull. Chem. Soc. J pn. 2002, 75,
1
179-1189.
8
83-897.
42) Belfield, K. D.; Wang, J . X. J . Polym. Sci., Part A: Polym.
Chem. 1995, 33, 1235-1242.
(4) Saltiel, J .; Charlton, J . L. In Rearrangements in Ground and
Excited States; de Mayo, P., Ed.; Academic Press: New York,
43) Cornil, J .; dosSantos, D. A.; Crispin, X.; Silbey, R.; Bredas,
J . J . Am. Chem. Soc. 1998, 120, 1289-1299.
1
980; Vol. 42-3, pp 25-89.
(
5) Saltiel, J .; Sun, Y.-P. In Photochromism, Molecules and
Systems; D u¨ rr, H., Bouas-Laurent, H., Eds.; Elsevier: Am-
sterdam, 1990; pp 64-164.
44) Rothberg, L. J .; Bao, Z. J . Phys.: Condens. Matter 2002, 14,
1
2261-12270.
45) GautierThianche, E.; Sentein, C.; Lorin, A.; Denis, C.; Rai-
mond, P.; Nunzi, J . J . Appl. Phys. 1998, 83, 4236-4241.
46) Saltiel, J . J . Am. Chem. Soc. 1967, 89, 1036-1037.
47) Saltiel, J .; Waller, A. S.; Sears, D. F.; Hoburg, E. A.; Zeglinski,
D. M.; Waldeck, D. H. J . Phys. Chem. 1994, 98, 10689-10698.
48) Cohen, R.; Ludmer, Z.; Yakhot, V. Chem. Phys. Lett. 1975,
(
(
(
(
6) Heikal, A. A.; Baskin, J . S.; Banares, L.; Zewail, A. H. J . Phys.
Chem. A 1997, 101, 572-590.
(
(
7) Schroeder, J .; Schwarzer, D.; Troe, J .; Vohringer, P. Chem.
Phys. Lett. 1994, 218, 43-50.
8) Lewis, F. D.; J ohnson, D. E. J . Photochem. 1977, 7, 421-
(
(
(
4
23.
3
4, 271-274.
9) Lewis, F. D. Acc. Chem. Res. 1979, 12, 152-158.
49) Cohen, M. D.; Green, B. S.; Ludmer, Z.; Schmidt, G. M. J .
Chem. Phys. Lett. 1970, 7, 486-490.
50) Carey, M. J .; Phillips, D. Eur. Polym. J . 2000, 36, 619-624.
(
10) Lewis, F. D.; Wu, T. F.; Burch, E. L.; Bassani, D. M.; Yang,
J . S.; Schneider, S.; J ager, W.; Letsinger, R. L. J . Am. Chem.
Soc. 1995, 117, 8785-8792.
(
11) Mohlmann, G. R. Synth. Met. 1990, 37, 207-221.
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