Self-Diffusion and Tracer Diffusion in Styrene/2-Vinylpyridine Block Copolymer Melts

Forced Rayleigh scattering (FRS) has been used to probe self-diffusion and tracer diffusion in unentangled, symmetric diblock copolymer melts. Two poly(styrene-b-2-vinylpyridine) (PS-PVP) diblocks, with M w = 1.1×10 4 and 2.2×10 4 , were synthesized anionically and end-labeled with a photochromic o-nitrostilbene derivative, and two PS homopolymers, with M w = 1.4×10 4 and 2.5×10 4 , were labeled with the same dye, randomly along the chain. Rheological measurements demonstrated that the lower M w diblock was in the disordered state and the higher M w diblock was in the ordered (lamellar) state, over the measurement temperature range (110-210°C)