Luminescence copolymer

Dias FB, Maiti M, Hintschich SI, Monkman AP (2005) Intramolecular fluorescence quenching in luminescent copolymers containing fluorenone and fluorene units A direct measurement of intrachain exciton hopping rate. J Chem Phys 122(5) 054904... 

Scheme 6 Europium complex as monomer for the preparation of humidity sensitive luminescent copolymers...

For copolymers of structure I, for both types of side-chains, there is a striking similarity with the optical properties of the corresponding models the absorption and photoluminescence maxima of the polymers arc only 0.08-0.09 eV red-shifted relative to those of the models, as shown in Figure 16-9 (left) for the octyloxy-substituted compounds. The small shift can be readily explained by the fact that in the copolymers the chromophorcs are actually substituted by silylene units, which have a weakly electron-donating character. The shifts between absorption and luminescence maxima are exactly the same for polymers and models and the width of the emission bands is almost identical. The quantum yields are only slightly reduced in the polymers. These results confirm that the active chro-mophores are the PPV-type blocks and that the silylene unit is an efficient re-conjugation interrupter. 

The composition of the copolymer determines its electroluminescence efficiency. Optimal efficiency (0.3%) was achieved in system 34 when the feed ratio of monomer 4 to monomer 34 was 9 1. This represents a 30-fold improvement in luminescence efficiency relative to PPV in the same device configuration (AlALOj/polymer/Al) 58, 62. Copolymer 33 has found uses as waveguides and... 

The possibility of conformational changes in chains between chemical junctions for weakly crosslinked CP in ionization is confirmed also by the investigation of the kinetic mobility of elements of the reticular structure by polarized luminescence [32, 33]. Polarized luminescence is used for the study of relaxation properties of structural elements with covalently bonded luminescent labels [44,45]. For a microdisperse form of a macroreticular MA-EDMA (2.5 mol% EDMA) copolymer (Fig. 9 a, curves 1 and 2), as compared to linear PM A, the inner structure of chain parts is more stable and the conformational transition is more distinct. A similar kind of dependence is also observed for a weakly crosslinked AA-EDMA (2.5 mol%) copolymer (Fig. 9b, curves 4 and 5). 

Photophysical Processes in Pol,y(ethy1eneterephthalate-co-4,4 -biphenyldicarboxyl ate) (PET-co-4,4 -BPDC). The absorption and luminescence properties of PET are summarized above. At room temperature the absorption spectrum of PET-co-4,4 -BPDC copolymers, with concentrations of 4,4 -BPDC ranging from 0.5 -5.0 mole percent, showed UV absorption spectra similar to that of PET in HFIP. The corrected fluorescence spectra of the copolymers in HFIP exhibited excitation maxima at 255 and 290 nm. The emission spectrum displayed emission from the terephthalate portion of the polymer, when excited by 255 nm radiation, and emission from the 4,4 -biphenyldicarboxylate portion of the polymer when excited with 290 nm radiation. 

The observed luminescence properties of the copolymer yarns can be easily explained if an energy transfer mechanism is assumed to be operating (Figure 7). Triplet-triplet energy transfer from the terephthalate units to the 4,4 -biphenyl -dicarboxyl ate units explains both the dual fluorescent/phospho-rescent emissions from the 4,4 -biphenyldicarboxyl ate units as well as the quenched phosphorescence from the terephthalate units. 

Microanalysis of the three PET-4,4 -SD copolymer yarns for sulfur yielded concentrations in agreement with the theoretical values. Since the 4,4 -SD comonomer was definitely incorporated into the three copolymer yarns, the absorption and luminescence characteristics of the copolymers point towards a co-absorption process between 4,4 -SD and PET rather than an electronic energy transfer process. 

TGA, iodometric, mid-IR, luminescence (fluorescence and phosphorescence) and colour formation (yellowness index according to standard method ASTM 1925) were all employed in a study of aspects of the thermal degradation of EVA copolymers [67], Figure 23 compares a set of spectra from the luminescence analysis reported in this work. In the initial spectra (Figure 23(a)) of the EVA copolymer, two excitation maxima at 237 and 283 nm are observed, which both give rise to one emission spectrum with a maximum at 366 nm weak shoulders... 

Binary molecular co-crystals of 2,5-bis(3-pyridyl)-l,3,4-oxadiazole and 2,5-bis-(4-pyridyl)-l,3,4-oxadiazole with benzene-1,3,5-tricarboxylic and benzene-1,2,4,5-tetracarboxylic acids were studied by X-ray and thermogravimetric analysis of mass loss <2005MI1247>. Dipole moments were used to study the flexoelectric effect in guest-host mixtures of 2,5-(4-pentylbenzene)-l,3,4-oxadiazole with commercial liquid crystal hosts <2005CM6354>. The luminescence properties of many other copolymers were also investigated (see Section 5.06.12.3). 

Several groups have studied introduction of phenylene ethynylene units into PPV backbones. The first material of this type, copolymer 163, was reported by Bunz and coworkers [193] (Chart 2.36). The material displayed blue luminescence in solution (A ax = 460 nm), but due to the polymer s rigid-rod structure, very strong aggregation in the solid state gave rise to... 

At Kodak, researchers used a rigid adamantane moiety to separate the luminescent oligo(phenylene vinylene) blocks (copolymers 182, 183) [213], The EL color can be tuned from blue (AEL = 470 nm) to green (AEL = 516 nm) by replacing a phenylene unit in 182 for 2,7-naphthylene (183). A very low turn-on voltage of 5.5 V (as for this class of materials) was achieved in the device ITO/182/Mg Ag, but no EL efficiency was reported (Chart 2.40). 

B. Sohn, K. Kim, D.S. Choi, Y.K. Kim, S.C. Jeoung, and J. Jin, Synthesis and luminescence properties of poly[2-(9,9-dihexylfluorene-2-yl)-l,4-phenylene vinylene] and its copolymers containing 2-(2-ethylhexyloxy)- 5-methoxy-l,4-phenylene vinylene units, Macromolecules, 35 2876-2881, 2002. 

E.-N. Chang and S.-A. Chen, Cyano-containing phenylene vinylene-based copolymer as blue luminescent and electron transport material in polymer light-emitting diodes, J. Appl. Phys., 85 2057-2061, 1999. 

J.K. Herrema, P.F. van Hutten, R.E. Gill, J. Wildeman, R.H. Wieringa, and G. Hadziioannou, Tuning of the luminescence in multiblock alternating copolymers. 1. Synthesis and spectroscopy of poly[(silanylene)thiophene]s, Macromolecules, 28 8102-8116, 1995. 

A. Berlin, G. Zotti, S. Zecchin, G. Schiavon, M. Cocchi, D. Virgili, and C. Sabatini, 3,4-Ethylenedioxy-substituted bithiophene-a/r-thiophene-5,5-dioxide regular copolymers. Synthesis and conductive, magnetic and luminescence properties, J. Mater. Chem., 13 27-33,2003. 

The dyes with long-lived luminescence are particularly attractive since background fluorescence can easily be discarded in time domain measurements. Crosssensitivity to oxygen may be problematic but it can be minimized by utilizing gas-blocking polymers. For example, Kuemer et al. [15] used the precipitation technique to prepare polyacrylonitrile-based beads doped with a ruthenium(II) complex which showed virtually no cross-sensitivity to oxygen. Copolymers of polyacrylonitrile and polyacrylic acid were used to provide the beads with... 

For some examples, see e.g. (a) Hogan CF, Harris AR, Bond AM et al (2006) Electrochemical studies of porphyrin-appended dendrimers. PhysChemChemPhys 8 2058-2065 (b) Jang W-D, Nishiyama N, Zhang G-D et al (2005) Supramolecular nanocarrier of anionic dendrimer porphyrins with cationic block copolymers modified with polyethylene glycol to enhance intracellular photodynamic efficacy. Angew Chem Int Ed 44 419 -23 (c) Loiseau F, Campagna S, Hameurlaine A et al (2005) Dendrimers made of porphyrin cores and carbazole chromophores as peripheral units. Absorption spectra, luminescence properties, and oxidation... 

In this work, we have chosen several systems stabilized through hydrogen bonds. The homopolymer is a polybase, i.e. PEO, PVME or PVP, and the copolymer is polyacrylic acid with various degrees of neutralization a, in which the acrylates are the non active groups. Complex formation is studied by potentiometry (because complexation induces a variation of the solution pH) and by viscometry and polarized luminescence which respectively give information about the macroscopic and local structure of the complex in solution. The influence of parameters such as the degree of neutralization of PAA a, the concentration ratio r - [polybase]/[PAA], the concentration and the molecular weight of polymers is examined. 

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