Hyperbranched Poly(fluorenevinylene)s Obtained from Self-Polymerization of 2,4,7-Tris(bromomethyl)-9,9-dihexylfluorene

Abstract

Hyperbranched poly(fluorenevinylene)s (HF0.04−HF0.17 and HF0.08-cap) were prepared from 2,4,7-tris(bromomethyl)-9,9-dihexylfluorene (A) by the Gilch reaction (the numbers represent monomer concentration in mmol/mL; cap: end-capped by benzyl bromide). The structural analysis of the hyperbranched products was obtained from their 1H NMR spectra, from which an almost linear relationship between degree of branching (DB) and monomer concentration has been correlated. The absorption peaks blue-shifts significantly from 430 nm for linear LF0.17-cap counterpart, which was prepared from 2,7-bis(bromomethyl)-9,9-dihexylfluorene (A′), to 372 nm for the hyperbranched poly(fluorenevinylene)s which degenerates further at higher degree of branching. However, the photoluminescence spectra of the HF films show peaks at ca. 467−468 nm, which is close to that of the LF0.17-cap film (473 nm), suggesting effective photoexcited energy transfer occurs between segments in the HF samples. The maximal luminance (2180 cd/m2) and max...