AbstractPoly(2‐vinylnaphthalene) and poly(2‐tert‐butyl‐6‐vinylnaphthalene) having small fractions of 2‐vinylanthracene were prepared to examine the effect of bulkytert‐butyl groups on the intramolecular singlet energy transfer from naphthalene to anthracene chromophore. The steric interactions of thetert‐butyl groups were found not only to reduce excimer formation and thereby increase the donor lifetime, but to suppress energy migration through the donor chromophores, giving a significant reduction of the overall tran