The novel organometallic−inorganic diblock copolymer, poly(ferrocenyldimethylsilane)-b-poly(dimethylsiloxane) (PFS-b-PDMS) (block ratio = 1.0:6.0) (M n = 35 100 g/mol with a narrow molecular weight distribution M w/M n = 1.10 based upon gel permeation chromatography in THF using polystyrene standards) forms long rodlike micelles in hexane solution. After the solvent was evaporated, transmission electron microscopy (TEM) and atomic force microscopy (AFM) showed that individual cylindrical micellar structures form with the iron-rich, organometallic PFS core encased in a sheath (corona) of PDMS. The block copolymer forms hexagonally packed cylinders in the bulk, and exposure to warm hexane causes the cylinders to disperse in the solvent. Both static and dynamic light scattering (SLS and DLS) were used to establish that the micelles are flexible rods which are stable in hexane even at 80 °C. The as-prepared sample possessed an aggregation number of ca. 2000 polymer molecules. Ultrasonication (60 W) in hexane led to the generation of short cylinders with an aggregation number of ca. 700. Since PFS can be oxidized to a semiconductive state and PDMS is an insulator, these rodlike micellar structures have the potential to function as nanoscale self-insulated wires.

We describe photoluminescent (PL) oxygen sensors based upon phosphorescent dyes adsorbed into the pores of mesoporous silica particles at submonolayer coverage on a layer-by-layer self-assembled film. Eight transition metal dyes (four Pt and Pd porphyrin complexes and four ruthenium complexes) were investigated through monitoring the changes in PL intensity and lifetime upon varying oxygen pressure. The intensity Stern-Volmer (SV) plots were curved. In most systems, the intensity SV plots match the lifetime SV plots, with deviations seen only at high oxygen pressures where static quenching may play a role. The curved intensity Stern-Volmer plots could be fitted with two phenomenological models, a two-site model, and a model based on a Freundlich binding isotherm for oxygen. The Gaussian distribution model was less successful in fitting the data. The most important result to emerge from these data is that the unquenched lifetime of the dye itself is not a sufficient scaling parameter to reduce all of the SV plots to a common line. A second scaling parameter was necessary. This parameter, which measures the capture radius for quenching (R eff ), times the efficiency of quenching per encounter R ranged from 0.38 nm for PdOEP and 0.42 for PtTPP to 1.12 for Ru(bpy) 3 ]Cl 2 and 1.25 for Ru(phen) 3 ]Cl 2 relative to an assumed value of RR eff ) 1.0 nm for PtOEP.

Three metal complexes[Re(bpy)(CO)3(CN-t-Bu)]Cl (1) (where bpy = 2,2-bipyridine), Bu4N[Ir(ppy)2(CN)2] (2), and Ir(ppy)3 (3) (where ppy = 2-phenylpyridine and Bu4N = tetrabutylammonium cation)were evaluated as oxygen sensors in poly((n-butylamino)thionylphosphazene) (nBuPTP) matrixes. The phosphorescent dyes 2 and 3 exhibit long lifetimes and high quantum yields in degassed dichloromethane and toluene solutions and when dissolved in the polymer matrix. These two dyes exhibited exponential decays both in solution and in the polymer films, with somewhat longer lifetimes (for 2, τ0 = 4.78 μs; for 3, τ0 = 1.40 μs) in the polymer film. All three dyes gave linear Stern−Volmer plots, but 1 was rather sensitive to photodecomposition. The slopes of the Stern−Volmer plots for these dyes were compared to those measured previously for platinum octaethyl porphine (PtOEP) and ruthenium tris-diphenylphenanthroline chloride ([Ru(dpp)3]Cl2. Attempts to explain the differences in slope using τ0 as the sole scaling parameter were unsuccessful. To explain these results, we calculated the effective capture radius for quenching by oxygen, which was 1.7 nm for 2 and 2.7 nm for 3, relative to a value of 1.0 nm for PtOEP. Thus, dye 3 is 2.7 times more sensitive to quenching by oxygen than PtOEP and more than 5 times more sensitive than [Ru(dpp)3]Cl2.

Page 6010. Gido et al. have previously reported the formation core-shell cylinders in solvent-cast films of poly(styrene-b-1,3-cyclohexadiene) (PS-b-PCHD) with a volume fraction of PCHD of ca. 0.37. Although our Communication focuses on an asymmetric block copolymer where the volume fraction of the minor phase forming the shell is 0.20, they were the first to report this type of morphology for a diblock copolymer in the bulk state. We regret not citing this reference [Macromolecules 1999, 32, 3216-3226].