The phase diagram of the system poly(styrene-block-n-butyl methacrylate)

The morphological phase diagram of poly(styrene-block-n-butyl methacrylate) , P(S-b-n-BMA), has been investigated in detail using thermal analysis, mic roscopy, rheology and scattering techniques. The system shows an upper crit ical order transition as well as a lower critical order transition (LCOT). For the first time, morphologies of the ordered system at higher temperatur es (LCOT) as well as of a block copolymer system frozen-in during the phase separation process are reported. The Flory-Huggins interaction parameter, chi depends not only on temperature, but also on the composition and the mo lecular weight of the block copolymers, resulting in an asymmetrical phase diagram. Furthermore, the deuteration of the PS block seems to increase the II parameter of the P[(dg)S-b-n-BMA] system, reflecting the influence of s mall changes in architecture on phase behavior. The phase behavior and morp hology of PS-b-PBMA are summarized in a phase diagram which is, however, qu ite complex and therefore needs further discussion. The equilibrium morphol ogies displayed are influenced by the temperature-dependent-conformation te rm as well as by the composition term.