Synthesis and third order optical nonlinearity studies of the donor–acceptor conjugated polymer, poly(2-[3,4-didodecyloxy-5-(1,3,4-oxadiazol-2-yl)thiophen-2-yl]-5-phenyl-1,3,4-oxadiazole) and a polymer/TiO2 nanocomposite

A donor–acceptor conjugated polymer (PDOThPOD) containing 3,4-didodecyloxythiophene and (1,3,4-oxadiazolyl)benzene units is synthesized by using precursor polyhydrazide route. Cyclic voltammetry studies reveal that the polymer possesses a low-lying LUMO energy level (−3.57 eV). A nanocomposite of polymer PDOThPOD and nano TiO2 is also prepared. The linear optical properties of PDOThPOD and the nanocomposite are studied using UV–vis absorption spectroscopy and fluorescence emission spectroscopy. z-scan technique is used to study the third order nonlinear optical properties of the polymer and nanocomposite films. Both polymer and nanocomposite films show a strong optical limiting behavior. The value of nonlinear absorption coefficient (β) is found to be of the order of 10−7 m/W, indicating that these materials are potentially suited for fabricating optical limiters.

Research highlights▶ 1,3,4-Oxadiazole unit increases the electron affinity of poly(alkoxythiophene). ▶ TiO2nanoparticles improve the thermal stability of the polymer. ▶ Polymer and nanocomposite films show a strong optical limiting behavior. ▶ TiO2nanoparticles enhance the nonlinear absorption coefficient value of the polymer.