Polydiacetylene and its composites with long effective conjugation lengths and tunable third-order nonlinear optical absorption

Abstract

Polydiacetylenes in either the blue or red phase have been extensively reported and studied in depth, while the fabrication of a pure bluish-green phase (PBG) polydiacetylene that has a remarkably long effective conjugation length is still an unachieved long-sought goal. Here, we report the facile fabrication of PBG polydiacetylene and its composites through the deliberate annealing suspensions of stabilizer-free crystals of the diacetylene monomer and diacetylene/metal ion composites, respectively, followed by UV-induced polymerization. Furthermore, it is confirmed that the composition with metal ions not only increases the conjugation length, but also tunes the type of the third-order nonlinear optical absorption (NLA) of the polydicetylene; different NLA types of the polydicetylene were obtained. To the best of our knowledge, this is the first example of the same linear conjugated polymer having different NLA types without the need for any chemical modification.