Synthesis and Characterization of Click Inspired Thiol-Ene-Fullerene Nanocomposites

This work explores the covalent incorporation of C60 and Sc3N@C80 fullerenes into thiol-ene networks by a facile, one-pot photochemical reaction with multifunctional thiol and alkene monomers. Synthesis of disulfide bonds within the tri-functional thiol monomer served to photochemically initiate the reaction when cleaved. This was followed by thermal curing of the pre-polymer for preparation of fullerene-containing thiol-ene films. Films were characterized by standard techniques including infrared spectroscopy, gel percent, and thermogravimetric analysis. The role of C60 and Sc3N@C80 as suitable alkenes for free-radical reaction with multifunctional thiols was investigated by preparing a series of thiol-films possessing a significant stoichiometric deficiency of alkyl ene monomer. Dynamic mechanical analysis of these films revealed an enhancement of the storage modulus values, increased glass transition temperatures, and increased network crosslink density with added C60 and Sc3N@C80. Investigation of the fullerene dispersion throughout the polymer was performed by transmission electron microscopy and revealed no significant aggregation of C60 or Sc3N@C80 in 1 wt % samples prepared by the pre-polymer method. To extend possible applications of this novel polymer nanocomposite, the preparation of fullerene-containing microspheres was pursued. An acoustic excitation coaxial flow (AECF) method was developed in this study to yield microspheres of narrow size dispersions. Microspheres were analyzed via optical microscopy, scanning electron microscopy, and dynamic light scattering. Microsphere production was determined to be dependent on the settings of the applied acoustic energy, as well as the viscosity of the discrete polymer solution, and flow rate of the non-solvent carrier phase. This presents the AECF method as a tunable technique for control of the microsphere diameter, with ability to prepare thiol-ene microspheres as small as 200 nm in diameter. C60 and Sc3N@C80 thiol-ene microspheres were prepared and characterized by differential scanning calorimetry, thermogravimetric analysis, and optical microscopy

Preparation and Preliminary Dielectric Characterization of Structured C\u3csub\u3e60\u3c/sub\u3e-Thiol-Ene Polymer Nanocomposites Assembled Using the Thiol-Ene Click Reaction

Fullerene-containing materials have the ability to store and release electrical energy. Therefore, fullerenes may ultimately find use in high-voltage equipment devices or as super capacitors for high electric energy storage due to this ease of manipulating their excellent dielectric properties and their high volume resistivity. A series of structured fullerene (C60) polymer nanocomposites were assembled using the thiol-ene click reaction, between alkyl thiols and allyl functionalized C60 derivatives. The resulting high-density C60-urethane-thiol-ene (C60-Thiol-Ene) networks possessed excellent mechanical properties. These novel networks were characterized using standard techniques, including infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermal gravimetric analysis (TGA). The dielectric spectra for the prepared samples were determined over a broad frequency range at room temperature using a broadband dielectric spectrometer and a semiconductor characterization system. The changes in thermo-mechanical and electrical properties of these novel fullerene-thiol-ene composite films were measured as a function of the C60 content, and samples characterized by high dielectric permittivity and low dielectric loss were produced. In this process, variations in chemical composition of the networks were correlated to performance characteristics