Optical‐limiting properties of poly(arylene ethynylenes) containing thiophene ring

Poly(arylene ethynylenes) containing thiophene ring were synthesized in good yield. In synthesis, pyridine was added to accelerate reaction owing to its phase transfer effect on CuI. The optical‐limiting properties of the prepared polymers were investigated with a Q‐switched Nd : YAG laser at 532 nm with 10‐ns pulse width. The experiments showed that the order of the optical‐limiting response of the polymers is poly(3‐hexyl‐2,5‐thienyleneethylene) (P3) > poly(2,5‐dihexyloxy‐1,4‐benzyleneethylene‐3‐hexyl‐2,5‐thienyleneethylene) (P2) > poly(9‐hexyl‐3,6‐carbazoleethylene‐3‐hexyl‐2,5‐thienyleneethylene) (P1). It can be understood well by the comparison of their conjugation length and D‐A structure. In addition, the results indicated that introducing the electron‐rich aromatic ring into the polymer backbone to enhance the D‐A structure would be an effective way to improve its optical‐limiting property.