Steady-state and time-dependent fluorescence measurements were made fo
r copolymers with pendant carbazole chromophores as a function of poly
mer coil collapse induced by the addition of a nonsolvent. The results
show that although the efficiency of electronic energy transport to a
covalently bound trap increases with coil contraction, this increase
is part of a complex chain of events, the most important being a decre
ase in donor quantum yield. It was found that classical excimer format
ion is small. for the polymers studied, while self-quenching is preval
ent and competes for donor energy. The result is that, as the efficien
cy of energy transfer increases, the quantum yield and fluorescence li
fetime of the donor decrease while the fluorescence intensity of the a
cceptor increases. It is quite likely that if self-quenching were elim
inated, the efficiency of electronic energy transfer would approach un
ity for a small degree of coil collapse.