A CRITICAL-EVALUATION OF DIRECT ENERGY-TRANSFER AS A TOOL FOR ANALYSIS OF NANOSCALE MORPHOLOGIES IN POLYMERS - APPLICATION TO BLOCK-COPOLYMER INTERFACES

Simulations of energy-transfer kinetics were carried out for a lamella r block copolymer system in which donor and acceptor dyes were attache d to the block junction. Ln such a system, the distribution of donors and accepters follows P-J(z), which describes the distribution of the junctions across the interface. We use these simulations to examine th e type of information about the block copolymer morphology available f rom analysis of fluorescence decay profiles generated by these systems . Within the context of a Helfand-Tagami distribution for P-J(z), one can obtain reliable estimates of the ratio of the period spacing to in terface thickness (H/delta) but not the individual parameters H and de lta. Since H can be determined independently in a scattering experimen t, this approach is useful for obtaining values of delta with better t han 5% accuracy. Attempts to distinguish a Helfand-Tagami profile from a Gaussian profile were not successful, The energy-transfer experimen t may be employed to reject the wrong morphology only if prior values of H and delta are determined by other methods.