Nanophase-Separated Synchronizing Structure with Parallel Double Periodicity from an Undecablock Terpolymer

A new nanophase-separated structure with parallel double periodicity has been identified for an undecablock terpolymer in bulk. The polymer includes two long poly(2-vinypyridine) ($P$) chains on each end, with five short polyisoprene ($I$) and four short polystyrene ($S$) chains at the center. This polymer exhibits a hierarchical lamellar structure with two crystallographic periods: 88 nm and 16 nm. The 88 nm period includes one thick $P$ lamella and five thin $I\mathrm{\text{−}}S\mathrm{\text{−}}I\mathrm{\text{−}}S\mathrm{\text{−}}I$ lamellae, of extremely high orientation.

Figure 1

Bright field transmission electron micrographs of the $PISISISISIP$ undecablock terpolymer. Sample specimens are ultrathin sections cut from solvent-cast and annealed film. Ultrathin sections were stained with iodine for (a) and osmium tetroxide for (b) and (c).

Figure 2

Small-angle x-ray scattering intensities. Film specimen is placed horizontally and x-ray incidents parallel to the film surface. (a) is a two-dimensional map on an imaging plate and this figure shows that lamellar orientation is extremely high. (b) shows the sector-averaged intensities within the sectors along the vertical line as a function of $q(=4\pi \sin \theta /\lambda )$, where $\lambda$ is the wavelength of x-ray and $2\theta$ is the scattering angle.

Figure 3

Possible molecular conformations of the undecablock terpolymer in lamellar nanophase-separated (a) three-layered, (b) five-layered, and (c) nine-layered structures.

Figure 4

Variation of relative fraction, $f$, for the $N$-layered structures as a function of $n$ for multiblock terpolymers of the $A(BC{)}_{n}BA$ type. The actual counted numbers of possible ways are shown in Table .