Synthesis and photophysical characterization of MWCNTs/poly(pyrrolyl methine) composite with large third-order optical nonlinearity

Highlights: • The sea-island structure was found and MWCNTs dispersed uniformly in PHPDTBE. • The maximum χ⁽³⁾ value of composite was 3.41 × 10⁻⁷ esu by DFWM technique at 532 nm. • The strong photoinduced electron transfer was confirmed by spectral studies. MWCNTs/poly (pyrrolyl methine) composites with the different contents of MWCNTs were synthesized by in-situ ultrasonic polymerization, and their structures and photophysical properties were also investigated. The results revealed that the third-order nonlinear optical susceptibility of MWCNTs/PHPDTBE composite showed a rapid increase with the increase of MWCNTs' content, and obtained a maximum value of 3.41 × 10⁻⁷ esu, which was almost ten times larger than that of PHPDTBE of 3.49 × 10⁻⁸ esu. The enhanced optical nonlinearity was attributed to strong photoinduced electron transfer from PHPDTBE to MWCNTs by right of their strong noncovalent π-π interaction in the photoexcited state.