A new approach to thick films of a block copolymer with ordered surface structures

A unique and simple method to prepare films with various ordered nanoscopic cylindrical patterns on the surface is reported. Various solutions of gemini surfactants with different spacers were used as a nanotemplate, on which thick polymer films were fabricated by the supramolecular assembly of a native or chemically modified polystyrene-block-poly(ethylene/butylene)-block-polystyrene(SEBS)tri-block copolymer. At the air/polymer surface, normal oriented cylindrical nanodomains formed by poly(ethylene/butylene) (PEB) block associates surrounded by polystyrene (PS) blocks are exhibited. While at the polymer/surfactant solution interface, parallel cylindrical nanodomains formed by PEB block stripes alternating with PS block stripes are observed. The ordered structure of the surface can be adjusted by changing the surfactant and the chemical nature of the polymer. In a special case using Gemini 16-1-Ph-1-16 and SEBS chemically modified with 2 wt.-% maleic anhydride, a nearly perfect hexagonal ordered structure is obtained. The AFM micrograph and associated FFT (inset) of the morphology of a SEBS thick film formed on a 16-1-Ph-1-16 solution to give a nearly perfect hexagonal ordered structure.