Allyloxyporphyrin-functionalized multiwalled carbon nanotubes: synthesis by radical polymerization and enhanced optical-limiting properties.

Allyloxyporphyrin-functionalized multiwalled carbon nanotubes (MWCNT-TPP) were synthesized by radical polymerization and characterized by FTIR, UV/Vis absorption, and X-ray photoelectron spectroscopy; elemental analysis; TEM; and thermogravimetric analysis. Z-scan studies revealed that this nanohybrid exhibits enhanced nonlinear optical (NLO) properties compared to a control sample consisting of a covalently unattached physical blend of MWCNTs and porphyrin, as well as to the separate MWCNTs and porphyrin. At the wavelengths used, the mechanism of enhanced optical limiting likely involves reverse saturable absorption, nonlinear scattering, and photoinduced electron/energy transfer between the MWCNTs and the porphyrin. The role of electron/energy transfer in the NLO performance of MWCNT-TPP was investigated by Raman and fluorescence spectroscopy.
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