Résumé
The directed self assembly of a 3-miktoarm star terpolymer (polyisoprene-arm-polystyrene-arm-polyferrocenylethylmethylsilane (3 mu-ISF)) into a (4.8(2)) square symmetry Archimedean tiling pattern is described. Bulk samples of 3 mu-ISF generate equilibrium columnar (4.8(2)) tile patterns (symmetry p 4 mm) on annealing, which is preceded by a metastable c 2 mm centered rectangular structure. In contrast, in thin films of 3 mu-ISF blended with PS homopolymer, the c 2 mm phase is stable with columns oriented out of plane when the film thickness is below 50 nm. However, the 3 mu-ISF/homopolymer blend rapidly forms a p 4 mm symmetry when the film thickness is similar to 80 nm, with grain sizes of several mu m and excellent order. Defects in the p4mm structure are described.