In order to better understand the kinetics and morphological changes of the polymer blend due to the copolymer additive, TEM was conducted on the blend with quench conditions designed to simulate the TJLS experiments.
The quenched samples were allowed to coarsen for the time required to reach a selected constant size, or q-value, at [Delta]T = 1.6 [degrees] C, using the TJLS kinetic data in Fig.
This size range agrees well with the q-range targeted from the TJLS data in Fig.
This is consistent with the TJLS result of [Alpha]/[Beta] [less than] 3, where we hypothesized that clearly defined phases at the coexistence compositions may not have been achieved.
The TEM results appear to be consistent with a blend compatibilization effect and also give a better understanding of the kinetics observed by TJLS. The lower intensity observed in the scattering data discussed above for Fig.
The equilibrium phase diagram, including the coexistence and spinodal curves for an asymmetric low molecular-weight PSD/PB blend with and without various amounts of a symmetrical diblock PSD-PB copolymer, has been determined by TJLS. A linear decrease in the critical temperature of the blend was observed with increasing diblock copolymer content for copolymer content less than [w.sub.BLK] = 0.12.
The morphology and kinetics of phase separation of the blend with low content of diblock copolymer ([w.sub.BLK] [less than or equal to] 0.086) were also studied by TJLS and TEM.
TJLS results indicate that the time dependence of the concentration fluctuation growth does not follow a universal functional form with diblock copolymer added.