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A sample of poly(ferrocenyldimethylsilane)- b-poly(2-vinylpyridine) (PFS 23- b-P2VP 230), with a short PFS block and a P2VP block 10-fold higher in degree of polymerization, forms spherical micelles when dissolved in ethanol. Over time (hours, days, and weeks), these solutions undergo a micelle sphere-to-cylinder transition eventually forming rather stiff, uniform fiber-like micelles with a core width of 10 nm, lengths between 20 and 50 µm, and approximately four polymer molecules per nm length. Here, we report the results of a combination of transmission electron microscopy, wide-angle X-ray scattering (WAXS), as well as static and dynamic laser light scattering measurements to follow the structural evolution. One key observation is the onset of partial aggregation of spherical micelles after an initial induction period (hours), so that the system as it ages consists of mixtures of free spherical micelles, micelle aggregates, and elongated structures with a high aspect ratio. Another important observation is the growth in intensity and sharpness of the WAXS peak characteristic of crystalline PFS domains as the number and uniformity of the cylindrical micelles increases. This formation of crystalline domains is the likely driving force for the structural transformation. [ABSTRACT FROM AUTHOR]

A new class of metal-containing diblock copolymers, PFS-b-P2VP (PFS poly(ferrocenyldimethylsilane), P2VP poly(2-vinylpyridine)), with a hydrophobic organometallic block and a highly polar hydrophilic organic block were synthesized via 1,1-dimethylsilacyclobutane (DMSB)-mediated sequential anionic polymerization. In the bulk state, PFS-b-P2VP copolymers with a volume fraction of PFS close to 0.20 give a morphology with cylindrical domains of PFS. A remarkable difference in the morphology of PFS-b-P2VP micelles was observed depending on the nature of selective solvent. Simply by using different alcoholic solvents either spherical or cylindrical micelles can be selectively formed from the same copolymer. WAXS experiments indicate that the crystallinity of the core-forming PFS block may be responsible for this difference. [ABSTRACT FROM AUTHOR]

A class of acenaphthene derivatives is shown to contain weak central carbon−carbon bonds that may be easily cleaved at high temperatures or even at ambient conditions to yield persistent free diradicals. To demonstrate the weak C−C bond strength, density functional theory calculations were carried out at several levels of theory for both the parent molecules and the diradicals resulting from the C−C bond cleavage. To assess the accuracy of the calculations, hexaphenylethane was chosen as a model compound due to its similarity with the molecules studied here, its great resonance stabilization, and long-standing history within the chemistry community. The C−C bond dissociation energy of hexaphenylethane was determined to be 11.3 ± 1.4 kcal/mol using a combination of isodesmic reactions and calculations at the M06-2X/6-31+G(d,p) level of theory. The types of molecules presented here are proposed as strong possibilities for the natural existence of free radicals in young and mature soot formed in hydrocarbon combustion. [ABSTRACT FROM AUTHOR]