Characterization of the excimers of poly(N-vinylcarbazole) using TRANES (original) (raw)
Related papers
Excimers in dilute solutions of N-vinyl carbazole/styrene copolymers of different molar compositions
Polymer, 2002
Steady-state fluorescence for dilute solutions of poly(N-vinyl carbazole) and N-vinyl carbazole/styrene copolymers of different molar monomer compositions upon excitation of carbazole groups were performed. I E /I M ratios depend on solvent nature, emission wavelength and copolymer composition. Molecular dynamics simulations on pure isotactic and sindiotactic fragments of different monomer compositions were used for identifying the amount and the conformations capable of forming intramolecular excimers. The analysis of theoretical results interprets the variation of the amount of intramolecular excimer with the molar monomer content. Types of complexes by total or partial overlapping between adjacent and non-adjacent carbazole chromophores were also distinguished.
The first optically active polycarbazoles
2003
The highly ordered chiral structures in naturally occurring polymers play a significant role in determining their precise and sophisticated biochemical functionalities. The design of synthetic helical polymers capable of emulating the chiral recognition properties of biopolymers is currently a focus of much interest. Enantioseparation, catalysis, and sensing are among the more promising applications of molecular recognition based on responsive three-dimensional intramolecular or intermolecular superchiral structures. 1-8 Optically active conjugated polymers 9-11 represent an attractive class of chiral macromolecules adaptable to this purpose because their chiral behavior can be augmented by nonlinear electrically conductive or optical properties 12-15 arising from conjugation along the backbone. In this Communication, we report the first example of optically active polycarbazoles. These novel chiral π-conjugated polymers are proposed to adopt a highly ordered chiral backbone conformation within a single polymer chain, but a chiral interchain π-stacking structure in their aggregates. The maintenance of the second-order chiral backbone conformation along each polymer chain during aggregation leads to a novel type of higher order chiral superstructure in the aggregates, suggesting that optically active polycarbazoles will be useful tools for developing and understanding chiral polymeric materials.
On the triplet state of poly(N-vinylcarbazole)
Chemical Physics Letters, 2004
Triplet state properties including transient triplet absorption spectrum, intersystem crossing yields in solution at room temperature and phosphorescence spectra, quantum yields and lifetimes at low temperature as well as singlet oxygen yields were obtained for poly(N-vinylcarbazole) (PVK) in 2-methyl-tetrahydrofuran (2-MeTHF), cyclohexane or benzene. The results allow the determination of the energy value for the lowest lying triplet state and also show that triplet formation and deactivation is a minor route for relaxation of the lowest excited singlet state of PVK. In addition, they show the triplet state is at higher energy than reported heavy metal dopants used for electrophosphorescent devices, such that if this is used as a host it will not quench their luminescence.
Polymer Degradation and Stability, 2006
This paper is devoted to the analysis of the photochemical behaviour of copolymers with carbazole units exposed to long-wavelength radiation. These copolymers are constituted of two types of carbazolylethyl methacrylate units (CEM) with octyl methacrylate moieties (OMA). The exposure of copolymers and PVK to UV light results in dramatic modifications of the physical and photophysical properties of the polymer. These modifications can be correlated with modifications of the chemical structure of the matrix. The photoageing of copolymers and PVK has been analysed by fluorescence, ESR, UVevis and infrared spectroscopies. The effects of crosslinking and chain scissions were determined by gel fraction measurements and size exclusion chromatography.
Journal of Polymer Science: Polymer Chemistry Edition, 1982
The effect of chlorine, bromine, and iodine at the 3 and 3,6 positions on a carbazole ring with thermodynamic properties, that is, enthalpy, entropy, and a stability constant of CT complex poly(Nvinylcarbazole-2,4,7-trinitrofluorenone, were studied in a temperature range of 26g323 K. The discussion of the results obtained, based on linear free-energy relationships, stressed the advantageous influence of the halogen substituent in the carbazole ring on the properties of the poly(N-vinylcarbazole)-2,4,7-trinitrofluorenone complex. EXPERIMENTAL Materials 2,4,7-Trinitrofluorenone, ICN USA; poly(N-vinylcarbazole) (PNVK), poly(N-vinyl-3-chlorocarbazole) (P3ClNVK), poly(N-vinyl-3,6-dichlorocarbazole) (P3,6CINVK), poly(N-vinyl-3-bromocarbazole) (P3BrNVK), poly(Nvinyl-3,6-dibromocarbazole) (P3,6BrNVK), poly(N-vinyl-3-iodocarbazole) (P3JNVK), and poly(N-vinyl-3,6-diiodocarbazole) (P3,6JNVK) were obtained from the radical polymerization of the monomers in the so1ution.l The preparatory fractionation was carried out by the elution method. The complexes were obtained with PNVHK fractions of intrinsic viscosities
Solution properties of poly(N-vinyl carbazole)—II. Thermodynamic properties in various solvents
European Polymer Journal, 1979
Thermodynamic properties of dilute solutions of Poly-N-vinyl carbazole obtained by cationic polimerization have been studied by viscometry in various solvents. The validities of some excluded volume theories have been tested and the unperturbed dimensions have been calculated. The dependencc of molecular dimensions, (s'-). on molecular weight and viscometric equations have also been determined.
Journal of Applied Polymer Science, 2009
In this work, a series of poly(4,4′-diphenylether-5,5′-bibenzimidazole)s (OPBIs) were synthesized from 4,4′-oxybis(benzoic acid) and 3,3′,4,4′-tetraaminobiphenyl through the variation of the initial monomer concentration with a solution polycondensation technique in a poly(phosphoric acid) medium. The resulting polymers were characterized by various techniques such as infrared (IR), nuclear magnetic resonance, dynamic mechanical analysis (DMA), and thermogravimetric analysis. The initial monomer concentration in the polymerization mixture played an important role in controlling the molecular weight of the resulting polymers. A temperature-dependent IR study showed that the free movement of the NH group of the imidazole ring was blocked by the absorbed moisture. The DMA study showed that the glass-transition temperature (Tg) varied with the molecular weight, and the presence of the ether linkage in the OPBI polymer backbone had a significant influence on Tg. A high-molecular-weight OPBI polymer tended to form a supramolecular organization, which influenced the thermal characteristic of the polymer. Photophysical studies demonstrated the fluorescent characteristics of the OPBI polymers in both solid and solution states. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthetic Metals, 1997
The electrochemical oxidation of title compounds (I and II) may yield dimers or polymers according to the effective experimental conditions. The structure of dimers (coupling at the 3 position of each carbazyl unit) was fully confirmed by comparison with chemically prepared samples. Polymerization may also occur anodically. Especially with dicarbazoles (II), redox polymers were obtained. Active centers were identified as being dimer units included in the polymer matrix. Product analysis was based upon voltammetric and spectroelectrochemical data of dimers and polymers. @ 1997 Elsevier Science S.A.
Copolymers of N-Vinylcarbazole and N,N-Dimethylaminoethyl Methacrylate
Copolymers of N-vinylcarbazole (NVC) and N,N-dimethylaminoethyl methacrylate (DMAEMA) were prepared by free-radical polymerization in a toluene solution at 60ЊC using 2,2 -azobisisobutyronitrile (AIBN) as an initiator. The reactivity ratios of both monomers were calculated using the extended Kelen-Tü dős method and found to be r 1 Å 0.441 { 0.052 and r 2 Å 1.632 { 0.102. The microstructure of copolymer chains is described on the basis of first-order Markov statistics. The microstructure of copolymers was also studied by UV and 1 H-NMR spectroscopy. Copolymers were characterized by viscosity and number-average molecular weight ( M V n ) measurements. The glass transition temperatures (T g ) of the copolymers were determined calorimetrically and the variation of T g with the copolymer composition is discussed.