Vertically Oriented Nanostructures of Poly(3-dodecylthiophene)-Containing Rod-Coil Block Copolymers

We introduced a star-shape molecular structure, 18 arm PS-b-P3DDT (STAR-SDDT) copolymers, to overcome large difference in surface tension. The STAR-SDDT with 47 % weight fraction of P3DDT block (w_P3DDT = 0.47) was synthesized by a combination of atom-transfer radical polymerization (ATRP) and click reaction. Both transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) revealed lamellar morphology of STAR-SDDT in bulk. When STAR-SDDT is spin-coated on a silicon substrate, vertically oriented lamellar microdomains were observed by tapping mode atomic-force microscopy (AFM) and grazing incidence small angle X-ray scattering (GISAXS). On the other hand, linear PS-b-P3DDT (LINEAR-SDDT) having lamellar structures only showed parallel structures with fibrils at surface in film. Also, we confirmed that the P3DDT crystalline locating inside microdomain is well formed, verified by the existence of (100) and (200) peaks of grazing incidence wide angle X-ray scattering (GIWAXS) spectrum.