Hiroyuki Furutani

Efficient blue electroluminescence of silylene-bridged 2-(2-naphthyl)indole

We synthesised 12,12-diisopropyl-7-methyl-12H-indololo[3,2-d]-naphtho[1,2-b][1]silole from 1-bromo-2-naphtholvia four steps. The silylene-bridged 2-(2-naphthyl)indole exhibited intense blue photoluminescence in solution and in the solid state. For example, the fluorescence maximum of the powder appeared at 476 nm with a high quantum yield (Φ = 0.70). The organic light-emitting device using the silylene-bridged indole as a light-emitting layer demonstrated a high current efficiency of 3.80 cd A−1 and a power efficiency of 3.64 lm W−1 at 10 mA cm−2 with excellent colour coordinates (0.152, 0.094), while the device fabricated with the blue-emissive indole as a dopant achieved even higher current and power efficiencies of 6.68 cd A−1 and 5.58 lm W−1, respectively, at 10 mA cm−2.

Novel Soluble Propargylether-Terminated Ester-Imide Prepolymers: I. Their Syntheses and Characteristics:

Novel ester-imide prepolymers terminated by 3-(4-aminophenoxy)-propane-1-yne (4-APE) as a thermally curable group were successfully synthesized. The practical preparation route for 4-APE via tosylate (2) is newly developed. Prepolymers were prepared from bisphenol-A bis(trimellitate)dianhydride (ESDA) having an ester moiety of dianhydride, aromatic diamine, and 4-APE. The properties of the cured resins of the prepolymers were evaluated and showed excellent mechanical and thermal properties, i.e. flexural strength of 269–370 MPa and T g’s of 225–269 °C. Moisture absorption of 0.20–0.78%, and dielectric constants of 3.0–3.2 were also measured.

Novel Propargylether-Terminated Ester-Imide Prepolymers: II. Matrix Resins for High-Temperature-Use composites:

Glass-cloth-reinforced composites were prepared from the state-of-the-art propargyl-ether-terminated ester-imide prepolymers developed in our laboratory. The composites demonstrated excellent initial mechanical properties and chemical properties, as well as electrical properties. The storage stability of the varnish of the prepolymer was evaluated at 0 °C and 20 °C. The flexural strength after ageing at various severe temperature levels in air was also demonstrated as a typical composite property. The initial flexural strength was well maintained even after 1000 h at 200 °C, 220 °C, and 240 °C.

Novel Propargylether-Terminated Ester-Imide Prepolymers: III. Thermoset/thermoset blend prepolymers as matrix resins for composites

Glass-cloth-reinforced composites were prepared from prepolymers of various weight ratio blends of the state-of-the-art propargylether-terminated ester-imide (1) and bismaleimide (MB-8000). The T g of a composite is directly related to the weight ratio of MB-8000 present. The composites demonstrated excellent initial mechanical properties. The chemical and electrical properties under severe long-ageing conditions were demonstrated.

Novel Soluble Ethynyl-Terminated Ester-Imide Prepolymers: Their Syntheses and Characteristics

Novel soluble ester-imide prepolymers consisting of bisphenol-A bis(trimellitate) dianhydride (ESDA), aromatic diamine, and 3-ethynylaniline(3-EA) as the thermosetting groups were synthesized. The prepolymers were quite soluble in DMAc, DMF, m-cresol, NMP, CHCl3, and THF. The T g’s of the various prepolymers were from 200 to 250 °C. The properties of the cured resins of the prepolymers were evaluated, and showed a range of cured T g’s from 262 to 285 °C and flexural strengths of 112–138 MPa. A low moisture absorption of 0.45% and a low dielectric constant of 3.1 were also observed. Properties of glass-cloth-reinforced composites using the ester-imide prepolymers as the matrix resin were evaluated, and excellent mechanical and thermal properties were observed. An SEM photograph of a cross section of either the cured resin or the glass-cloth-reinforced composite showed good resin flow. Synthesis and some molecular orbital energies of ESDA were also studied.