Luminescent and light refractive polymers: synthesis and optical and photonic properties of poly(arylene ethynylene)s carrying silole and tetraphenylethene luminogenic units.

A facile route for the synthesis of luminescent and light refractive polymers is proposed. Silole-containing diyne and halogenated tetraphenylethene derivatives are synthesized and their coupling reactions furnish poly(arylene ethynylene)s with high molecular weights in high yields. All of the polymers are soluble and film-forming and possess a high thermal stability. They emit strong green lights when their solutions and nanoparticle suspensions are photoexcited. The polymers show high refractive indices with low chromatic dispersions. Their RI values can be modulated and their thin films can be crosslinked using UV irradiation, generating negative photoresist patterns.

Conjugated hyperbranched poly(aryleneethynylene)s: synthesis, photophysical properties, superquenching by explosive, photopatternability, and tunable high refractive indices.

Triphenylamine (TPA)-based conjugated hyperbranched poly(aryleneethynylene)s (PAEs), hb-P1/2, hb-P1/3, and hb-P1/4, were synthesized with high molecular weights and good solubilities through Sonogashira coupling reactions. These PAEs exhibited outstanding thermal stabilities and different emission behaviors. Tetraphenylethene (TPE)-containing hb-P1/2 fluoresced faintly in THF, although its light emission was enhanced by aggregate formation in aqueous media or in thin films, thereby exhibiting an aggregation-induced emission-enhancement (AIEE) effect. Whereas 1,1,2,3,4,5-hexaphenylsilole (HPS)-bearing hb-P1/3 showed no significant change in emission intensity with increasing water content in aqueous media, hb-P1/4, which consisted of TPA-fluorenone donor-acceptor groups, presented almost identical absorptions, but both positive and negative solvatochromic emissions in various solvents. A superquenching effect was observed in the picric-acid-detection process by using nanosuspensions of hb-P1/2. All of the polymers possessed good film formability. UV irradiation of the thin films induced simultaneous photobleaching and cross-linking, thus making them applicable in the fabrication of 2D and 3D patterns. Furthermore, the polymer films also showed high refractive indices, which were tunable upon exposure to UV light.

Ferrocene-functionalized disubstituted polyacetylenes with high light refractivity: synthesis through polymer reaction by using click chemistry and application as precursors to magnetic nanoparticles.

Ferrocene-functionalized disubstituted polyacetylenes are synthesized in high yields by copper-catalyzed click reactions of azido-decorated poly(1-phenyl-1-hexyne) and poly(diphenylacetylene) with 1-ethynylferrocene. All the organometallic polymers are soluble and film-forming. They enjoy high thermal stability (≥300 °C) and are redox-active. Thanks to the ferrocenyl units, thin films of the polymers show high refractive indices (n=1.745-1.698) in the wavelength region of 400-1700 nm as well as high Abbé numbers (v(D)' up to 426) and low optical dispersions (D' down to 0.002) at telecommunication important wavelengths. Pyrolyses of the polymers under nitrogen furnish magnetic ceramics with high magnetizabilities.

Synthesis and curing of hyperbranched poly(triazole)s with click polymerization for improved adhesion strength.

We successfully synthesized hyperbranched poly(triazole)s by in situ click polymerization of diazides 1 and triyne 2 monomers on different metal surfaces (copper, iron, and aluminum) and characterized their adhesive properties. Optimizations were performed to obtain high adhesive strength at different temperatures by analyzing the effects of curing kinetics, annealing temperature and time, catalyst, monomer ratio, surface conditions, alkyl chain length of diazides 1, etc. The adhesive bonding strength with metal substrate is 2 orders of magnitude higher than similar hyperbranched poly(triazole)s made by click polymerization and clearly higher than some commercial adhesives at elevated temperatures. With the same conditions, adhesives prepared on aluminum and iron substrates have higher adhesive strength than those prepared on copper substrate, and an excess of triyne 2 monomer in synthesis has greater adhesive strength than an excess of diazide 1 monomer. Tof-SIMS experiment was employed to understand these phenomena, and the existence of an interphase between the polymer and metal surface was found to be critical for adhesive bonding with thicker interphase (excess of triyne 2 monomer) and the higher binding energy between polymer atoms and substrate atoms (e.g., aluminum substrate) generating the higher bonding strength. In addition, the light-emitting property of synthesized polymers under UV irradiation can be used to check the failure mode of adhesive bonding.

Aggregation-Induced Emission in a Hyperbranched Poly(silylenevinylene) and Superamplification in Its Emission Quenching by Explosives.

A silicon-containing hyperbranched polymer (hb-P1/2) with σ*-π* conjugation was prepared in a good yield and high molecular weight by rhodium-catalyzed alkyne polyhydrosilylation of 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene (1) with tris(4-dimethylsilylphenyl)amine (2). The polymer was thermally stable, losing merely 5% of its weight when heated to ≈445 °C. Whereas hb-P1/2 was weakly luminescent when molecularly dissolved, it became highly emissive when supramolecularly aggregated, showing an aggregation-induced emission (AIE) phenomenon. A superamplification effect was observed when the AIE nanoaggregates were used as fluorescent chemosensor for explosive detection: the quenching efficiency was greatly increased in a nonlinear fashion with increasing quencher concentration.

A New Disubstituted Polyacetylene for the Detection of α-Amino Acids.

New imidazole-functionalized disubstituted polyacetylene was synthesized by utilizing the postfunctional strategy. In addition, its ability to sense copper ions and α-amino acids by fluorescence quenching has been studied. The quenching of the fluorescence of the imidazole-functionalized disubstituted polyacetylene was observed at a very low level of Cu(2+) (7.0 × 10(-7) mol · L(-1) ). The fluorescent intensity decreased rapidly upon the increase of the concentration of the added solution of Cu(2+) . It was expected that the addition of α-amino acids to the solution of the polyacetylene/Cu(2+) complex could turn on the fluorescence of the polyacetylene, if α-amino acids could remove the copper ions from the complex. Glycine, was used for testing: upon the addition of glycine the quenched fluorescence of P1 turned on immediately. The detection limit was as low as 6.0 × 10(-5) mol · L(-1) .

Synthesis and light-emitting properties of disubstituted polyacetylenes carrying chromophoric naphthylethynylphenyl pendants.

Poly(1-phenyl-1-alkyne)s bearing chromophoric pendants and containing alkyl spacers (-{(C 6H 5)CC[(CH 2) m OCOC 6H 4CCNp]} n - [P 1( m) ( m = 3, 4, 9); Np = 1-naphthyl]) were synthesized, and the effects of structural variations on the optical properties, especially electroluminescence, of the polymers were investigated. The monomers were prepared in high yields by esterification and coupling reactions of n-phenyl-( n - 1)-alkyn-1-ols. Selective polymerizations of the 1-phenyl-1-alkyne unit of the monomers were effected by WCl 6-Ph 4Sn catalyst, affording polymers with high molecular weights ( M w up to 63 000) in high yields (up to 83%). Structures and properties of the polymers were characterized and evaluated by IR, NMR, TGA, UV, PL, and EL analyses. All the polymers are thermally very stable, losing almost no weight when heated up to 400 degrees C. Photoexcitation of the polymer solutions induces strong blue light emission at 460 nm, with quantum yields up to 98%. No aggregation quenching was observed when the polymers were fabricated into solid films. Multilayer EL devices with the configuration of ITO/P 1( m):PVK/BCP/Alq 3/LiF/Al were fabricated, which emitted blue light with luminance up to 498 cd/m (2). The device performance varied with the spacer length ( m), with P 1(4) giving the highest external quantum efficiency of 0.47%. The value was further enhanced to 0.86% by optimizing the layer thickness and inserting a hole-injection layer.

Aggregation-enhanced emissions of intramolecular excimers in disubstituted polyacetylenes.

Whereas chain aggregation commonly quenches light emission of conjugated polymers, we here report a phenomenon of aggregation-induced emission enhancement (AIEE): luminescence of polyacetylenes is dramatically boosted by aggregate formation. Upon photoexcitation, poly(1-phenyl-1-alkyne)s and poly(diphenylacetylene)s emit blue and green lights, respectively, in dilute THF solutions. The polymers become more emissive when their chains are induced to aggregate by adding water into their THF solutions. The polymer emissions are also enhanced by increasing concentration and decreasing temperature. Lifetime measurements reveal that the excited species of the polymers become longer-lived in the aggregates. Conformational simulations suggest that the polymer chains contain n=3 repeat units that facilitate the formation of intramolecular excimers. The AIEE effects of the polymers are rationalized to be caused by the restrictions of their intramolecular rotations by the aggregate formation.

Fluorescence enhancements of benzene-cored luminophors by restricted intramolecular rotations: AIE and AIEE effects.

Photoluminescence of simple arylbenzenes with ready synthetic accessibility is enhanced by two orders of magnitude through aggregate formation; viscosity and temperature effects indicate that the emission enhancement is due to the restriction of their intramolecular rotations in the solid state.