A Molecular Dynamics Simulation on the Self‐Assembly of ABC Triblock Copolymers, 1. Effects of Block Composition in Symmetric Triblock Copolymers

The self‐assembly of ABC triblock copolymers in the microphase‐separated state is investigated using an isothermal‐isobaric molecular dynamics simulation. For the validation of our simulation scheme, ABA triblock copolymers are also simulated. We examine the effect of the composition (f_B) of symmetric triblock copolymers on the morphology realized in these copolymers, keeping other parameters fixed. For ABA triblock copolymers, the transition from lamellar to cylindrical morphologies is observed with increasing the composition from f_B = 0.5 to f_B = 0.75, and such behavior is supported by calculation results of scattering patterns. These simulated results agree well with experimental and theoretical ones, validating our simulation method. More complex structures are predicted for ABC triblock copolymers. If midblock B is the minor component, its structures are changed from lamellar, cylindrical, to spherical morphology at the interface between A/C lamellae as f_B decreases. For ABC triblock copolymers with the midblock B as the major component, the morphology of end blocks in the matrix composed of the midblock is changed from tricontinuous to spherical structures as f_B increases.     

Preparation of Polyacrylonitrile Microfibers Using Gelation and Phase Separation During the Solution Polymerization of Acrylonitrile

Polyacrylonitrile (PAN) microfibrils were prepared directly via the solution polymerization of acrylonitrile at specified ratios of controlling solvent dimethyl sulfoxide (DMSO) to non‐solvent tert‐butyl alcohol. At first, gel formation occurred due to the interaction between DMSO and the cyano groups of PAN. The microfibrillar structure was then formed through the phase separation of PAN molecules from the gel. It is shown that very small variations in the solvent/non‐solvent ratio facilitate a major change in the gelation and phase separation processes.     

The reaction of 2‐amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]‐thiophene with diethyl malonate: synthesis of coumarin,pyridine, and thiazole derivatives

The reaction of 2‐amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]thiophene ( 1 ) with diethyl malonate ( 2 ) gave two products: 3 and 4 . The reactivity of 3 toward a variety of chemical reagents was studied to give azoles, azines, and their fused derivatives. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:168–175, 2001     

Selective reductions in the sphere of organophosphorus compounds

Recent results on the selective reduction of cyclic vinylphosphine oxides and vinylphosphinates, as well as their refunctionalization by the use of borane, are summarized. The selective reduction of the phosphorus moiety of unsaturated phosphonates, phosphinates, and phosphine oxides is also discussed. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:161–167, 2001     

Synthesis and characterization of a new green‐emitting poly(phenylenevinylene) derivative containing alkylsilylphenyl pendant

A new type of processable green‐emissive polymer containing alkylsilylphenyl units was synthesized via Gilch polymerization. The resulting polymer was soluble in organic solvents and was spin‐cast to make a thin film. A light‐emitting diode was fabricated by the polymer being sandwiched between indium tin oxide and metal electrodes. A strong green emission at 524 nm was observed from the various device configurations made by the newly synthesized polymer. The polymer had a strong absorption band around 427 nm that was attributable to a π–π* transition of the conjugated segments of the polymer. A current–voltage–luminance curve showed typical rectifying diode characteristics. The polymer had a very high molecular weight (number‐average molecular weight = ∼300,000) with a polydispersity of about 3 and good thermal stability up to 400 °C. The brightness at 13 and 17 V was about 1000 and 5900 cd/m², respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4185–4193, 2000