Four different poly(tert-butoxystyrene)-b-polystyrene-b-poly(4-vinylpyridine)(PtBOS-b-P S-b-P4VP) linear triblock copolymers, with the P4VP weight fraction varying from 0.08 to 0.39, were synthesized via sequential anionic polymerization. The values of the unknown interaction parameters between styrene and tert-butoxystyrene and between tert-butoxystyrene and 4-vinylpyridine were determined from random copolymer blend miscibility studies and found to satisfy 0.031 < chi(S.tBOS) < 0.034 and 0.39 < chi(4VP.tBOS) <0.43, the latter being slightly larger than the known 0.30