Amphiphilic Liquid-Crystalline 4-Miktoarm Star Copolymers with a Siloxane Junction Leading to Cylindrically Nanostructured Templates for a Siloxane-Based Nanodot Array

摘要

Well-defined A(3)B-, A(2)B(2)-, and AB(3)-type 4-miktoarm star copolymers (M-n = 10,500-16,200, M-w/M-n = 1.16-1.18) consisting of poly(ethylene oxide) (PEO) and polymethacrylate bearing an azobenzene mesogen (PMA(Az)) as the arms and cyclotetrasiloxane as the core unit were synthesized using a combined route composed of a thiol-ene click reaction and atom transfer radical polymerization. Microphase-separated structures of the star copolymers in thin films with a thickness of approximately 100 nm were investigated by GISAXS and TEM. The A(3)B-type star-(PEO)(3)[PMA(Az)](1) copolymer formed a more highly ordered PEO cylinder array with perpendicular alignment in the PMA(Az) matrix than that of the corresponding linear-type block copolymer. The center-to-center distance of the PEO cylinders and the cylinder diameter were 13 and 4 nm, respectively. The highly ordered star-(PEO)(3)[PMA(Az)](1) thin film was directly transferred to a siloxane-based nanodot array by oxygen reactive ion etching. (C) 2015 Wiley Periodicals, Inc.