Polydispersity-driven transition from the orthorhombic Fddd network to lamellae in poly(isoprene-b-styrene-b-ethylene oxide) triblock terpolymers

Recent developments in the synthetic techniques such as controlled radical polymerization have increased the number of monomers that can be readily incorporated into block copolymer materials. Blending of monodispersed poly(styrene-b-2-vinylpyridine) diblock and poly(2-vinylpyridine-b-styrene-b-2- vinylpyridine) triblock copolymers was also investigated that demonstrated increase in the domain spacing with increasing polydispersity. The investigations of the broad, continuous molecular weight distributions focused on systems with two chemically distinct blocks where the polydisperse blocks have one chain end not constrained to a domain surface. The hydroxy- functionalized SI diblocks with a polydisperse PS block and a nearly monodisperse PI block was prepared by anionic polymerization in cyclohexane using the functional organolithium 3-triisopropylsilyloxy-1-propyllithium (TIPSO-PrLi). The results show that moderate polydispersity can alter the morphology of triblock terpolymers.