For the first time, photoluminescence properties of four polysilylcarbodiimides, comprised of a phenyl pendant group attached at the silicon atom and a second substituent being either phenyl (S1), methyl (S2), hydrogen (S3) or vinyl (S4), are reported. Distinctive fluorescence emissions are detected in the polymers with one phenyl group at the silicon atom (S2, S3 and S4), due to a phenyl excimer emission. The polymer with two phenyl groups attached at the same silicon atom (S1) shows, besides the phenyl excimer emission, also a vibrationally structured emission stemming from the Ph-SiX 2-Ph unit. Moreover, the polysilylcarbodiimides were heat-treated at different temperatures up to 500°C in argon flow. In this case, the amount of crosslinking is identified to be responsible for a bathochromic shift of the maximum emission spectra with increasing annealing temperature. After annealing at 300°C, polymers S2 and S3 present a red-shifted emission due to rearrangement reactions of the basic polymer structure. Furthermore, the presence of free carbon formed during the annealing procedure in the form of polycyclic aromatic hydrocarbons, as well-defined fragments of graphene, are proven to contribute to the photoluminescence properties of the heat-treated polysilylcarbodiimides.
- polycyclic aromatic hydrocarbons
- polymer-derived ceramics
ASJC Scopus subject areas
- Inorganic Chemistry