ma9b00724_si_001.pdf (263.4 kB)
Bicontinuous Double-Diamond Structures Formed in Ternary Blends of AB Diblock Copolymers with Block Chains of Different Lengths
journal contribution
posted on 2019-08-22, 21:29 authored by Wataru Takagi, Jiro Suzuki, Yoshitaka Aoyama, Tomohiro Mihira, Atsushi Takano, Yushu MatsushitaWe
report on the formation of a bicontinuous double diamond (DD)
structure in ternary blends of poly(styrene-b-isoprene)
(SI) diblock copolymers with chains of different lengths merely in
a polyisoprene block. Certainly, the materials revealing the DD structure
with mesoscopic length scale have strongly been expected due to high
potential for applications; however, it is difficult to form owing
to thermodynamically evident disadvantages such as wider surface area
and larger domain thickness variation, particularly for monodisperse
copolymers. The DD structure was successfully formed for ternary blends
composed of three parent diblock copolymers; SI-L (M = 190k, φs = 0.46), SI-G (M =
151k, φs = 0.62), and SI-C (M =
124k, φs = 0.73), resulting in covering the overall
composition range 0.57 ≤ φs ≤ 0.60, where φss denotes volume fractions of polystyrene
blocks. Four-branched double network structure with space group symmetry
of Pn3̅m was clearly proved
by transmission electron microscopy (TEM) observation aided by computer
simulation, combined with diffracted data by small angle X-ray scattering.
In addition, TEM tomography gave direct information concerning interwoven
double networks and four-branching nature of the diamond framework.