GAUSSIAN-COIL TO STRETCHED-COIL TRANSITION IN BLOCK COPOLYMER MELTS

Two scaling regimes, DN with =0.49 0.02 and 0.80 0.04, have been identified in a model set of nearly symmetric diblock copolymer melts, where D and N are the system peridocity and degree of polymerization, respectively. The crossover from =0.49 to 0.80 is identified as the Gaussian to stretched-coil transition (GST). Contrary to current theory, the GST occurs well below the order-disorder transition (ODT), NGST=0.57NODT. We associate =0.80 with the crossover from weak-segregation (=1/2) to strong-segregation (=2/3) behavior. © 1990 The American Physical Society.