MICRODOMAINS IN BLOCK-COPOLYMERS AND MULTIPLETS IN IONOMERS - PARALLELS IN BEHAVIOR

The microdomain structure in block-copolymer melts with short A blocks which strongly attract each other separated by long B blocks is studied for the case of narrow interphases between the microdomains. It is shown that as the temperature is lowered (or attraction of A blocks becomes more intensive), the behavior of the system changes qualitatively: instead of the usual strong segregation regime a new regime emerges which we define as the ''superstrong segregation regime''. In this regime A chains within the micelles become practically completely extended and steric restrictions on the chain conformations in the micelles become important. Although the superstrong segregation regime is not characteristic for ordinary block copolymers, it is easily realized for the case when one of the blocks is ionomeric. By considering the limiting case of one monomer link in the A block we obtain the results for microdomain (multiplet) structure in random ionomers. In most cases multiplets in ionomers correspond to microdomains in block copolymers in the superstrong segregation regime. We calculate the limiting size of the multiplet, the average distance between the multiplets, and the expansion of the chains in ionomer melts. The comparison of multiplets for random and telechelic ionomers is also performed.