Formation of Pseudoisocyanine J-Aggregates in Poly(vinyl alcohol) Fibers by Electrospinning

摘要

Submicrometer diameter, light emitting fibers of poly(vinyl alcohol) (PVA) doped with pseudoisocyanine(1,1′-diethyl-2,2′-cyanine bromide, PIC) dye were prepared by electrospinning. A horizontal setup was employedwith a stationary collector consisting of two parallel-positioned metal strips separated by a void gap. Formationof uniaxially aligned and randomly deposited fibers in electrospun films was confirmed by microscopy.Photoluminescence (PL) spectroscopy is used to evaluate spectral properties of both types of fibers dopedwith PIC. While PIC molecules were individually dispersed in PVA solution, they assemble into J-aggregatesupon electrospinning when the weight fraction of PIC molecules is above 2.5 wt %. The formation ofJ-aggregates was observed in both randomly deposited and uniaxially aligned electrospun fibers. Moreover,the fibers aligned uniaxially showed a high degree of polarized emission (PL|/PL⊥)10), arising from theorientation of J-aggregates along the fiber axis. On the other hand, isotropic emission of J-aggregates wasobserved from the fibers deposited randomly. As a conclusion, electrospinning was found to be an efficientand a practical method to form highly oriented J-aggregates dispersed into polymer fibers. To the best of ourknowledge, it is the first time formation of J-aggregates (a bottom-up approach) and electrospinning (a topdown approach) is successfully combined.