Synthesis and Self-Assembly of Rod$_{2}$Coil Miktoarm Star Copolymers of Poly(3-dodecxylthiophene) and Poly(methyl methacrylate) with high rod fractions

Poly(3-dodecylthiophene)-b-poly(methyl methacrylate) diblock copolymer (P3DDT-$b$-PMMA) can self-assembled into various microdomains such as spheres, cylinders, and lamellae depending on weight fraction of P3DDT. However, only filbril morphology was formed when weight fraction of P3DDT ($w_{\mathrm{P3DDT}})$ was major ($w_{\mathrm{P3DDT}}$ $\sim$ 0.76). Here, we introduce a new approach to obtain microdomain structures even at high $w_{\mathrm{P3DDT}}$ by using well-defined A$_{\mathrm{2}}$B miktoarm star copolymer composed of P3DDT and PMMA ((P3DDT)$_{\mathrm{2}}$PMMA. We found via small angle X-ray scattering and transmission electron microscopy that (P3DDT)$_{2}$PMMA showed PMMA cylinder packed hexagonally in the matrix of P3DDT and body-centered-cubic spheres of PMMA for $w_{\mathrm{P3DDT}}$ of 0.66 and 0.75, respectively. This because of much reduction of the rod-rod interaction in (P3DDT)$_{\mathrm{2}}$PMMA compared with P3DDT-$b$-PMMA diblock copolymers.