Fluorescence investigation of model compounds for light-emitting alternating copolymers in heterogeneous environments.
In this paper, the fluorescence spectra of the model compounds M(TPA-PPV) and M(TPA-PAV) of novel light-emitting alternating copolymers, were studied and the effect of KNO3 on the interaction between the model compounds and the ionic micelle-water interface was also investigated. The following is found: (i) the fluorescence changes of M(TPA-PPV) are related to the state of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) solution: (ii) an aggregated state can be formed in M(TPA-PAV) solution at low concentration of CTAB; (iii) higher concentrations of KNO3 may affect the interaction between the model compounds and the ionic micelle-water interface.
New light emitting materials : Alternating copolymers with hole transport and emitting chromophores
A new type of novel high-efficiency light-emitting nitrogen-containing poly(phenylene vinylene) (PPV)-related copolymers, which have hole-transfer moieties such as triphenylamine (TPA) and conjugated aromatic units such as 4,4'-biphenylene, 1,4-phenylene, 2,5-dimethyl-1,4-phenylene, 1,4- or 1,5-naphthylene, and 9,10-anthrylene, was designed and synthesized by the well-known Wittig-Hornor reaction. The resulting alternating copolymers were highly soluble in common organic solvents. They can spin-cast onto various substrates to give highly transparent homogeneous thin films without heat treatment. The introduction of TPA units in the PPV backbone improved processibility and limited the π-conjugation length. Furthermore, the additional π-electron delocalization between the lone-paired electron in the nitrogen atom and π-electrons in the conjugated units contributed to the improvement of the fluorescence quantum yields of these copolymers. All these alternating copolymers except TPA-PAV have high-efficiency photoluminescence and they are very promising for light-emitting diodes (LEDs). It is very promising that TPA-PAV will emit white light when used in LED device due to the broad emission spectra. The origin of the broad spectrum is contributed by the charge-transfer complex formation, which can be proved by the absorption and emission spectra of TPA-PAV solutions. When the aromatic units were 1,4-phenylene, 1,4- or 1,5-naphthylene, 4,4'-biphenylene, and 9,10-anthrylene, respectively, with increase of the capability to accept electrons in aromatic units, the charge transfer from TPA to aromatic units occurred; consequently, the fluorescence quantum yield decreased. The introduction of the alkoxy-substitute group on the aromatic units in the polymer backbone caused the red shift of the absorption and emission spectra of the copolymers due to the stronger delocalization of the «-conjugated system.
An introduction to dramatherapy
What Is Dramatherapy? Theory into Practice Preparing for Dramatherapy Beginning a Dramatherapy Session Applying Dramatherapy The Heart of Dramatherapy Dramatherapy and 'Mental Illness' Dramatherapy and Other Forms of Disorder of Mind Other Client Groups and Dramatherapy