| Abstract |
Two series of hyperbranched polymers based on alkyl modified 2,4,6-tris(thiophen-2-yl)-1,3,5-triazine central units linked through fluorene bridges of different lengths have been synthesized via Suzuki coupling. The two series of polymers differ in the position of alkyl substitution within the thienyl group, which can be either closer to the triazine core (P0-P10) or to the fluorene bridge (P0 -P10 ). Introduction of a hexyl group at one of the beta-positions of the thienyl group improves the solubility of the polymers. A good control over the ratio of triazine and fluorene units allows for the systematic study of the polymer composition effects on the electro-chemical, linear, and nonlinear photophysical properties. The nonlinear absorption has been shown to have a noticeable promotion with increasing molar ratio of the triazine core, while the emission quantum yield decreases. The position of alkyl substitution within the thienyl group has a significant effect on the two-photon absorption cross section. Substitution at the beta-position of the thienyl group closer to the triazine unit favors nonlinear absorption in the P0-P10 series when compared to the P0 -P10 series. These polymers perform considerably better as nonlinear absorbers than their unsubstituted analogues. |
