The dependence of excimer formation of polystyrene solutions on solvent and concentration

Abstract

The fluorescence spectra of polystyrene solutions have been measured in various solvents. The ratio of the intensity ID of the excimer (short 1iving.excited dimer) band to the intensity IM of the monomer band depends on the solvent. The values extrapolated t o diluted solutions may be related to the average density of segments in a polymer molecule. Above concentrations of 0.1 g/100 ml, the ratio ID/IM increases with increasing concentration, and the peak position of the excimer band shifts to a longer wavelength. ZUSAMMENFASSUNG:In verschiedenen Losungsmitteln wurden die Fluoreszenz-Spektren des Polystyrols gemessen. Das Verhaltnis der Intensitat ID der Excimer(kurzlebendes, angeregtes Dimeres)-Bande zu der Intensitat IM der Monomer-Bande hangt vom Losungsmittel ab. Die Werte konnen, extrapoliert nach kleinen Konzentrationen, zur durchschnittlichen Segmentdichte im Polymermolekul in Beziehung gesetzt werden. Oberhalb der Konzentration 0,l g/100 ml wachst das Verhaltnis ID/IM mit der Konzentration an, und die Excimer-Bande verschiebt sich nach langerer Wellenlange.

Fluorescence excitation spectroscopy of polystyrene near the critical concentration c*

“…Nishihara and Kaneko 16 demonstrated that increasing the concentration of polystyrene caused an increase in the ratio of excimer to monomer intensity (I E /I M ) even for dilute concentrations. This contradicted an earlier study by Vala et al 17 who reported little change in the I E /I M ratio of dilute solutions.…”

177Lu‐[DOTA0,Tyr3] octreotate therapy in patients with disseminated neuroendocrine tumors: Analysis of dosimetry with impact on future therapeutic strategy

“…There have been studies of intermolecular excimer formation in polystyrene using fluorescence emission spectroscopy. Nishihara and Kaneko16 demonstrated that increasing the concentration of polystyrene caused an increase in the ratio of excimer to monomer intensity ( I / I M ) even for dilute concentrations. This contradicted an earlier study by Vala et al17 who reported little change in the I E / I M ratio of dilute solutions.…”

Time-resolved fluorescence techniques in polymer and biopolymer studies

“…In dilute solution, both monomer and excimer fluorescence is observable (Fig. 21) 6, 81,107,131,192,221) It has been reported that in ethyl acetate and dichloroethane solution, the position of the excimer band is concentration dependent 131) The interpretation of solvent effects is complex. Since the compactness of the polymer coil will affect the efficiency of energy migration and the concentration of aromatic species in conformations suitable for excimer formation, solvent effects are to be expected in polymers in which excimer formation is the result of nearest-neighb0ur interactions 5), as is the case in styrene as shown in studies on styrene.methyl methacrylate copolymers zT)…”

“…In view of more recent work on other vinyl aromatic polymers, it would be of interest to study poly(styrene) further with more sophisticated techniques. As in the case of poty(styrene) in fluid solution both excimer and monomer fluorescence is observed in polymers containing the pendant naphthalene chromophore 2, s, 30, 10% 131,155,156,173,192) In a preliminary study on the time-resolution of fluorescence in poly(1-vinyl naphthalene) 64) the kinetics were constrained to fit Scheme 1, yielding values of monomer decay times in methylene chloride solution of 7.4 and 43.1 ns. Late.gated spectra indicated that reverse dissociation of the excimer occurred.…”