Multilayer fullerenes (carbon nano-onions, CNOs) represent a largely unexplored carbon allotrope due to their inherent insolubility. Expectations are that the properties of these nano-onions will be unique and potentially useful, as has been the case with the fullerenes and carbon nanotubes (CNTs). CNOs show diminished chemical reactivity; however, the established thermal diradical formation and reactivity of bis-o-diynyl arene (BODA) monomers afforded direct functionalization, solution processing, and de-functionalization of CNOs; and the first example of a radical addition of a conjugated polymer to CNOs. The functionalized and soluble CNOs were characterized by TEM, GPC, TGA, Raman spectroscopy, and XPS. A CNO defunctionalization method using oxidative TGA is also presented.

Bis‐ortho‐diynylarene (BODA) monomers, prepared from common bisphenols in three high yielding steps, undergo free‐radical‐mediated thermal polymerization via an initial Bergman cyclo‐rearrangement. Polymerization is carried out at 210 °C in solution or neat with large pre‐vitrification melt windows (4–5 h) to form branched oligomers containing reactive pendant and terminal aryldiynes. Melt‐ and solution‐processable oligomers with weight‐average molecular weight Mw = 3000–24 000 g mol–1 can be coated as a thin film or molded using soft lithography techniques. Subsequent curing to 450 °C affords network polymers with no detectable glass transition temperatures below 400 °C and thermal stability ranging from 0.5–1.5 % h–1 isothermal weight loss measured at 450 °C under nitrogen. Heating to 900–1000 °C gives semiconductive glassy carbon in high yield. BODA monomer synthesis, network characterization and kinetics, processability, thin‐film photoluminescence, and thermal properties are described.

Inverse opaline photonic crystal structures are created from carbon precursor polymer networks derived from the thermal Bergman cyclopolymerization of bis-ortho-diynyl arene (BODA) monomers. A new hydroxy-functional BODA monomer was prepared that exhibited excellent compatibility with silica opal templates. Monomer melt infiltration of the template, in situ thermal polymerization, and pyrolysis, followed by removal of the silica with HF affords a carbon inverse opal structure that conserves the original dimensions of the template. The photonic crystal was characterized by the reflectance spectra, and the refractive index of the carbon was estimated. The functionality of the carbon opal as a sensor element was demonstrated with water/acetonitrile mixtures and reveals a bandstop shift of 13 nm over a refractive index change of 0.011.

No abstract

No abstract